NOVEL PROCESS

The present invention relates to a novel process for preparing certain statistical branched amphiphilic copolymers. The present invention also relates to the copolymers and compositions formed by this process and the use of these polymers and compositions in the preparation of emulsions, which can then be subject to cross-linking to form polymeric capsules. The present invention also relates to a novel emulsion process for preparing crosslinked polymeric capsules and to the crosslinked polymeric capsules formed by this process. The polymeric capsules can be used to encapsulate benefit agent compounds (e.g. pharmaceuticals or agrochemicals; nutritional agents such as vitamins; cosmetics, catalysts, dyes, pigments, flavours, fragrances, lubricating oils, emollients, natural oils, and waxes, paints, inks, coatings, and sealants) present in the dispersed phase of the emulsion.

BACKGROUND TO THE INVENTION

The ability to encapsulate and protect benefit agents using a facile and non- hazardous procedure is in great demand. The encapsulation of a benefit agent is typically achieved by the formation of a wall or capsule around the benefit agent, or by forming a dispersion or solution of the benefit agent in a suitable solvent or carrier medium. It is preferential if this whole procedure can be achieved by a simple process and which does not involve the use of toxic materials and/or require time consuming procedures. In general, the benefit agent or carrier medium is typically hydrophobic and, once encapsulated, it is dispersed in an aqueous medium or formulation.

Encapsulation can be used to protect or isolate delicate and/or reactive species from other components within a formulation, or to decrease a physical process, such as dispersion within the formulation or evaporation from the formulation such as in the case of volatile benefit agents. Encapsulation can also be used to provide a chemically-modified wall structure around the benefit agent which can further enhance delivery or be tuned to respond to an external physical or chemical stimulus to achieve release of the benefit agent, such as temperature, pressure, pH, dilution or an electromagnetic change. Current encapsulation methodologies typically rely on the formation of a wall or capsule around a benefit agent, or the solution or dispersion of the benefit agent within a carrier medium, for example the encapsulation of an oil within an aqueous medium. In the case of oil-in-water encapsulation, a typical process would involve the formation and stabilisation of an oil-in-water emulsion followed by a chemical cross-linking process at the oil-water interface to form a capsule or encapsulate around the dispersed oil droplets. The stabilisation of the dispersed phase is typically achieved by using a surfactant system to achieve an emulsion droplet. Cross-linking of the formed emulsion can then be achieved by mutually reactive species at the oil-water interface, such as a di-or poly-isocyanate and a di- or poly- amine. It is usual that each of the mutually reactive components are dispersed within the dispersed and the continuous phase and this is typically referred to as interfacial polymerisation.

An alternative, and commonly used, methodology is where the emulsion droplets are reacted further to achieve a cross-linked particle or, alternatively, an additional cross- linker material, which may be present either within the encapsulated droplet or external to the emulsion droplet, is reacted to give a cross-linked shell.

A common procedure to achieve encapsulation is through the use of a sol-gel reaction of an alkoxysilane. In this methodology a stable oil-in-water emulsion is formed whereby an alkoxysilane, such as tetraethoxysilane, is emulsified in addition to a hydrophobic benefit agent or carrier material. Following the introduction of a base into the aqueous continuous phase, an interfacial cross-linking reaction takes place to form a silicate shell at the oil-water interface, thereby giving rise to a cross- linked capsule. This methodology is particularly inefficient as a large amount of alkoxysilane must be used in order to achieve efficient shell formation at the interface and there is an undesirable non-controlled formation of cross-linked particles within, and external to, the capsule. In addition, the emulsion droplets, once formed, must be reacted swiftly as the alkoxysilane is hydrolytically unstable and there is also the possibility of reaction with a reactive hydrophobic benefit agent or carrier payload. Furthermore, the multi-component nature of this synthesis complicates scale-up processes and can impact on the reproducibility of the synthesis. An alternative mechanism to achieve cross-linked particles is via the direct physical or chemical cross-linking of the emulsifying agent. In many of these strategies, the emulsifier of choice is a block copolymer, where the self-assembly of the block copolymer leads to the efficient formation of the emulsion droplet. The subsequent cross-linking reaction is typically via the formation of an intermolecular covalent bond between copolymer chains at the same oil/water interface to achieve a cross-linked polymeric capsule. The initial emulsion droplet template is stabilised by the amphiphilic block copolymer, though unfortunately the tedious synthesis of these controlled polymer structures and the common use of toxic small molecule cross- linking agents, in addition to the subsequent clean-up steps post-reaction, renders these methodologies unsuitable for non-specialised applications. In addition, block copolymer stabilised droplets can also suffer from instability issues where droplet coalescence and demulsification can occur.

Alternatively, encapsulation can proceed through the reaction of suitable moieties on the copolymer chains without the addition of a cross-linker. WO2013/024307 describes the preparation of statistical amphiphilic branched addition copolymers with moieties that are capable of reacting to form intra- and inter-molecular crosslinks. The copolymers function as emulsifiers and can react with one another to form a covalently cross-linked capsule at the oil-water interface. However, there remains a need for further improved processes for preparing these copolymers and for forming polymer capsules/encapsulates using these polymers.

The present invention was devised with the foregoing in mind. SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a method of preparing a statistical branched amphiphilic copolymer in a carrier oil, wherein the branched copolymer comprises: at least two chains which are covalently linked by a bridge other than at their ends; and wherein the at least two chains are formed by the polymerisation of one or more ethylenically monounsatu rated monomers and the bridge is formed by the polymerisation of one or more ethylenically polyunsaturated monomers; and wherein the one or more ethylenically monounsaturated monomers comprise a monomer of Formula (1 ):

H ₂ C=CH(Ri)-C(O)-O-R2-Si(OR3)3

Formula (1 ) wherein Ri is H or an optionally substituted (1 -4C)alkyl group; R2 is a (2- 8C)alkylene group and R3 is an optionally substituted (1 -4C)alkyl group; and wherein at least one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) is a hydrophilic residue; and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) is a hydrophobic residue, and wherein the mole ratio of polyunsaturated monomer(s) to monounsaturated monomer(s) is between a range of from 1 :100 to 1 :4; and wherein said polymer is formed by an addition polymerisation process, which comprises mixing together:

(a) the one or more ethylenically monounsaturated monomer;

(b) from 1 to 25 mole% (based on the number of moles of monounsaturated monomer(s)) of the one or more ethylenically polyunsaturated monomer;

(c) a chain transfer agent; and

(d) an initiator; in a carrier oil and subsequently reacting said mixture to form the statistical branched amphiphilic copolymer.

In a second aspect, the present invention provides a statistical branched amphiphilic copolymer in a carrier oil obtainable by, obtained by, directly obtained by, or formed by, a process as defined in the first aspect of the invention.

In a third aspect, the present invention provides a composition comprising a statistical branched amphiphilic copolymer as defined in the first aspect of the invention in a carrier oil. Suitably, the statistical branched amphiphilic copolymer is obtainable by, obtained by, directly obtained by, or formed by, a process as defined in the first aspect of the invention. Suitably, the composition is a solution of the copolymer in the carrier oil, but it may also be a dispersion. In a fourth aspect, the present invention provides an emulsion formed by emulsifying a carrier oil composition as defined in the third aspect of the present invention, or as formed by the process of the first aspect of the invention, with an aqueous phase.

In a fifth aspect, the present invention provides a process for forming an emulsion as defined in the fourth aspect of the invention, the process comprising: providing a carrier oil comprising a statistical branched amphiphilic copolymer, wherein said polymer is formed within the carrier oil as defined above in relation to the first aspect of the invention; providing an aqueous phase; and emulsifying the carrier oil and aqueous phases to form an emulsion.

In a sixth aspect, the present invention provides a process for forming a polymer capsule, the process comprising: providing a carrier oil comprising a statistical branched amphiphilic copolymer, wherein said polymer is formed within the carrier oil as defined above in relation to the first aspect of the invention; providing an aqueous phase; emulsifying the carrier oil and aqueous phases to form an emulsion; and facilitating the cross-linking of the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the aqueous phase and the carrier oil.

In a seventh aspect, the present invention provides a polymer capsule obtainable by, obtained by, directly obtained by, or formed by, a process as defined in the sixth aspect of the invention.

According to an eighth aspect of the present invention there is provided a method of preparing a polymeric capsule, the process comprising: providing a mixture comprising an oil phase, an aqueous phase, a statistical branched amphiphilic copolymer emulsifier, a first polymerisable species present in the oil phase, a second polymerisable species present in the aqueous phase, wherein said first and second polymerisable species can react with one another to form a polymer; emulsifying the mixture to form an emulsion having a dispersed phase and a continuous phase; forming a polymeric capsule by the reaction between the first and second polymerisable species at the oil/water interface.

In a ninth aspect, the present invention provides a polymer capsule obtainable by, obtained by, directly obtained by, or formed by, a process as defined in the eighth aspect of the invention.

According to a tenth aspect of the present invention there is provided a method of preparing a crosslinked polymeric capsule, the process comprising: providing a mixture comprising an oil phase, an aqueous phase, a statistical branched amphiphilic copolymer bearing one or more functional groups and a crosslinking agent bearing two or more functional groups capable of reacting with the functional groups present on the statistical branched amphiphilic copolymer to form crosslinks between adjacent copolymer molecules; emulsifying the mixture to form an emulsion; allowing the crosslinking agent to react with the functional groups on the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the oil phase and the aqueous phase; wherein the statistical branched amphiphilic copolymer comprises at least two polymeric chains which are covalently linked by a bridge; and wherein the at least two chains are formed by the polymerisation of one or more ethylenically monounsaturated monomers and the bridge is formed by the polymerisation of at least one ethylenically polyunsaturated monomer; and wherein the copolymer comprises one or more functional groups capable of reacting with functional groups present on the crosslinking agent.

In an eleventh aspect, the present invention provides a polymer capsule obtainable by, obtained by, directly obtained by, or formed by, a process as defined in the tenth aspect of the invention. DESCRIPTION OF THE INVENTION

DEFINITIONS

The following definitions pertain to chemical structures, molecular segments and substituents:

The ethylenically monounsatu rated monomer is also referred to as a 'monofunctional monomer'. The ethylenically polyunsaturated monomer is referred to as 'multifunctional monomer' or brancher.

The term 'alkyl' as used herein refers to a branched or unbranched saturated hydrocarbon group which may contain from 1 to 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl etc. Unless otherwise stated herein, an alkyl group typically contains from 1 to 6, and even more typically 1 to 4 carbon atoms. Methyl, ethyl and propyl groups are especially preferred. 'Substituted alkyl' refers to alkyl substituted with one or more substituent groups. Preferably, alkyl and substituted alkyl groups are unbranched.

The term 'alkylene' is used herein to refer to a branched or unbranched saturated divalent hydrocarbon linker group which may contain from 1 to 12 carbon atoms, such as, for example, methylene, ethylene, n-propylene, isopropylene, n-butylene etc. Typically, an alkylene group contains from 1 to 6, and even more typically 1 to 4 carbon atoms. Methylene, ethylene and propylene groups are generally preferred. 'Substituted alkylene' refers to alkylenes substituted with one or more substituent groups. Preferably, alkylene and substituted alkylene groups are unbranched.

When a group is referred to as being "optionally substituted", it will be appreciated that the group may be substituted by one or more substituent groups. Typical substituent groups include, for example, halogen atoms, nitro, cyano, hydroxyl, cycloalkyl, alkyl, alkenyl, haloalkyl, alkoxy, haloalkoxy, amino, alkylamino, dialkylamino, formyl, alkoxycarbonyl, carboxyl, alkanoyl, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylsulfonato, arylsulfinyl, arylsulfonyl, arylsulfonato, phosphinyl, phosphonyl, carbamoyl, amido, alkylamido, aryl, aralkyl and quaternary ammonium groups, such as betaine groups. Of these substituent groups, halogen atoms, cyano, hydroxyl, alkyl, haloalkyl, alkoxy, haloalkoxy, amino, carboxyl, amido and quaternary ammonium groups, such as betaine groups, are particularly preferred. When any of the foregoing substituents represents or contains an alkyl or alkenyl substituent moiety, this may be linear or branched and may contain up to 12, preferably up to 6, and especially preferred is up to 4, carbon atoms. A cycloalkyl group may contain from 3 to 8, preferably from 3 to 6, carbon atoms. An aryl group or moiety may contain from 6 to10 carbon atoms, with phenyl groups being especially preferred. A halogen atom may be a fluorine, chlorine, bromine or iodine atom and any group which contains a halo moiety, such as a haloalkyl group, may thus contain any one or more of these halogen atoms.

Terms such as '(meth)acrylic acid' embrace both methacrylic acid and acrylic acid. Analogous terms should be construed similarly.

Terms such as 'alk/aryl' embrace alkyl, aralkyl (e.g. benzyl) and aryl groups and moieties.

Molecular weights of monomers and polymers are expressed as weight average molecular weights (Mw), except where otherwise specified.

ASPECTS 1 TO 7 OF THE INVENTION

Process for forming statistical branched amphiphilic copolymer

As indicated above, the present invention provides a method of preparing a statistical branched amphiphilic copolymer in a carrier oil, wherein the branched copolymer comprises: at least two chains which are covalently linked by a bridge other than at their ends; and wherein the at least two chains are formed by the polymerisation of one or more ethylenically monounsatu rated monomers and the bridge is formed by the polymerisation of one or more ethylenically polyunsaturated monomers; and wherein the one or more ethylenically monounsatu rated monomers comprise a monomer of Formula (1 ):

H ₂ C=CH(Ri)-C(O)-O-R2-Si(OR3)3

Formula (1 ) wherein Ri is H or an optionally substituted (1 -4C)alkyl group; R2 is a (2- 8C)alkylene group and R3 is an optionally substituted (1 -4C)alkyl group; and wherein at least one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) is a hydrophilic residue; and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) is a hydrophobic residue, and wherein the mole ratio of polyunsaturated monomer(s) to monounsaturated monomer(s) is between a range of from 1 :100 to 1 :4; and wherein said polymer is formed by an addition polymerisation process, which comprises mixing together:

(a) the one or more ethylenically monounsaturated monomer;

(b) from 1 to 25 mole% (based on the number of moles of monounsaturated monomer(s)) of the one or more ethylenically polyunsaturated monomer;

(c) a chain transfer agent; and

(d) an initiator; in a carrier oil and subsequently reacting said mixture to form the statistical branched amphiphilic copolymer.

The statistical branched amphiphilic copolymer

Typically, the statistical branched amphiphilic copolymers further comprises a residue of a chain transfer agent and optionally a residue of an initiator.

In an aspect of the invention, the statistical branched amphiphilic copolymer is as defined above and further comprises a residue of a chain transfer agent and a residue of an initiator and wherein at least one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophilic residue; and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophobic residue.

The statistical branched amphiphilic copolymer/carrier oil solutions of the present invention can be emulsified with a suitable aqueous phase. The copolymer stabilises the emulsion droplets and can then be cross-linked in order to form polymeric capsules or shells around the dispersed emulsion droplets, effectively encapsulating the dispersed emulsion droplets and any benefit agent contained therein. The emulsions stabilised may be oil-in-water or water-in-oil, or so-called double emulsions (water-in-oil-in-water or oil-in-water-in-oil emulsions). Typically, the emulsion will be an oil-in-water emulsion. The copolymers stabilise the emulsions efficiently at low concentrations without the need for additional co-stabilisers or surfactants. Once the emulsion is formed, the co-polymer can be chemically cross- linked to form a polymeric capsule or shell. One or more species or benefit agents present in the dispersed phase of the emulsion can be encapsulated within the polymeric capsule or shell that is formed around the droplets of the dispersed phase of the emulsion. The chemical cross-linking is achieved by the reaction of the functional trialkoxysilyl moieties of formula I present in the copolymer chains. These moieties can react with one another to covalently bind adjacent copolymer molecules together to form a cross-linked polymer capsule or shell. There is no particular need to include further cross-linking groups or to have additional separate cross-linking steps, although the use of additional cross-linking groups and/or additional cross- linking steps as part of the process is not precluded in the process of the present invention.

The co-polymers of the invention are amphiphilic addition copolymers. Amphiphilic addition copolymers can be used to stabilise oil-in-water emulsions, in particular branched co-polymers are especially useful as they have been shown to form extremely stable emulsions at low dose due to their high molecular weight, branched architectures and chemical composition. These branched copolymers effectively stabilise oil-in-water emulsions more effectively than equivalent linear materials. The inclusion of a functional trialkoxysilyl-functional monomer of formula I (such as trimethoxysilylpropylmethacrylate) in the copolymer structure results in a functional copolymer emulsifier which can form inter-molecular cross-links when subject to hydrolysis in an aqueous environment, which is optionally catalysed by the presence of an acid or base. This forms a covalently bonded polymeric capsule around the dispersed phase without the need for a further reactive cross-linker molecule or subsequent chemical cross-linking steps. A further advantage of the invention is the facile preparation of the addition copolymers because they are polymerised within a carrier oil. There is also the flexibility to tune their functionality through the selection of polymer constituents such as monomers, and where applicable, chain transfer agents.

The amphiphilic copolymers according to the present invention are branched. The branched, non-cross-linked addition amphiphilic copolymers may include statistical, graft, gradient and alternating branched copolymers. The copolymers comprise at least two chains which are covalently linked by a bridge other than at their ends, which is to be understood as a polymer wherein a sample of said polymer comprises on average at least two chains which are covalently linked by a bridge other than at their ends. When a sample of the polymer is prepared, there may be accidentally some polymer molecules which are unbranched, which is inherent to the production method (addition polymerisation process). For the same reason, a small quantity of the polymer will not have a chain transfer agent at a chain end.

To function in the desired manner, the addition copolymer of the present invention must have certain attributes as discussed further below.

Amphiphilicity: The addition copolymer must be amphiphilic, i.e. it contains moieties capable of associating with the dispersed (internal) and continuous (bulk) phases of the emulsion. That is the copolymer must contain hydrophilic and hydrophobic units within the copolymer structure. Hydrophobicity is typically achieved by using hydrophobic monomers such as alkyl-functional monomers, e.g. an alkyl methacrylate, and/or via a hydrophobic chain transfer agent such as an alkyl mercaptan, e.g. dodecanethiol. Additionally, the copolymer must have hydrophilic functionality, again typically achieved by the use of hydrophilic monomers, for example the monomer could be neutral, for example poly(ethylene glycol)-functional monomers such as mono-methoxypoly(ethylene glycol) methacrylate, or the monomer could be charged in nature, such as acrylic or methacrylic acid or weakly basic monomers, e.g. dimethyl or diethylaminoethyl methacrylate or their respective salts. The hydrophilic unit can be responsive in nature whereby the hydrophilicity can be altered by an external stimulus such as pH or temperature, such as in the case of N-isopropylacrylamide. The hydrophilic and hydrophobic units could also be introduced through the ethylenically polyunsaturated monomer (brancher) or chain transfer agent where applicable.

In an embodiment, the hydrophilic monomer may be of high molecular weight, such that at least one of the ethylenically monounsatu rated monomer, the ethylenically polyunsaturated monomer and/or the chain transfer agent is a hydrophilic residue having a molecular weight of at least 400 Daltons (e.g. at least 1 ,000 Daltons). In an embodiment, the hydrophilic component is derived from the ethylenically polyunsaturated monomer. In another embodiment, the hydrophilic component is the chain transfer agent. In a preferred embodiment, the hydrophilic component is the ethylenically monounsatu rated monomer. In all cases, a combination of hydrophilic components is possible and may be desirable.

Higher molecular weight hydrophobic species are typically more hydrophobic than lower molecular weight hydrophobic species. Preferably, the hydrophobic component is derived from the polyunsaturated monomer, more preferably from the chain transfer agent (during conventional free-radical polymerisation) or the initiator, but most preferably from a monounsaturated monomer. In all cases, a combination of hydrophobic components is possible and may be desirable.

Functionality: The addition copolymer must also possess a cross-linking monomer of formula I, and optionally one or more further cross-linking monomer groups in the copolymer structure, which are capable of reacting with adjacent co-polymer molecules to form inter-molecular covalent cross-links and therefore provide a cross- linked polymeric capsule around the dispersed phase. The inclusion of alkoxysilane-functional monomers of formula I, such as trimethoxysilylpropylmethacrylate, where the crosslinking occurs via a sol-gel process is required. In addition to the monomeric component of formula I, the polymer capsule formation can be further aided by providing other mutually reactive groups in the copolymer structure, including those which can form intermolecular ester, amide, urethane, urea linkages or those associated by a nucleophilic substitution or addition reactions, for example the reaction of an epoxide with a nucleophile such as an amine or an alkoxide which can occur through the reaction of a residue of glycidyl(meth)acrylate with an amine residue derived from aminoethyl(meth)acrylate or the reaction of a benzyl halide moiety such as a residue derived from a vinylbenzyl chloride monomer with an amine moiety such as that derived from a residue from a dimethylamino ethyl (methacrylate) monomer

Branched addition polymers: Branched addition amphiphilic copolymers have been shown to efficiently emulsify and ultimately cross-link around a hydrophobic internal phase to form capsules or aggregated cross-linked structures. In order for the branched addition polymers to be suitable for use in encapsulation technologies the polymer must possess a number of structural components. Typically, the branched addition copolymers are used to emulsify, and ultimately encapsulate, a hydrophobic oil in an aqueous bulk phase. Essentially the branched addition polymer must be capable of forming a stable emulsion which can then be further reacted to give a stable cross-linked polymeric capsule. It is preferred if this reaction can occur without the addition of a further functional monomer; that is the branched addition copolymer emulsifier contains a functional group which can self-react to give a cross- linked shell around the capsule. To avoid tedious and costly purification steps the branched addition polymers are prepared within the carrier phase and used without further isolation in the emulsification and encapsulation processes.

Post emulsification - self condensation: As the post-emulsification cross-linking reaction takes place through reaction of functional groups already present within the copolymer emulsifiers, the encapsulation procedure can occur efficiently without the need for additional, commonly toxic, cross-linkers. Thus, the copolymer acts as both emulsifier and a cross-linker. Additionally, the emulsion or polymer capsule can be further chemically reacted post-emulsification, or post-encapsulation, to give further chemical species at the surface of the emulsion or polymer capsule which may be of benefit, for example in improved substrate affinity. Self-cross-linking can occur between copolymer residues on the same interface to form capsules or between copolymer emulsifiers on adjacent interfaces to form monoliths.

The carrier oil

The term "carrier oil" is used herein to refer to an organic or "oil" phase having a boiling point of greater than 80°C. Typically, the carrier oil will have a boiling point of greater than 100°C, more typically greater than 120°C and most typically greater than 130°C. Such carrier oils are generally considered to be non-volatile liquids at ambient temperature and pressure. The elevated boiling points of the carrier oils enable the polymerisation reaction to proceed at an elevated temperature, which can significantly reduce the polymerisation reaction time.

Any suitable carrier oil can be used. The carrier oil is preferably the same carrier oil that will be used as the dispersed or bulk phase in the subsequent emulsion process, i.e. the co-polymer is synthesised directly within the carrier oil that will form the dispersed or bulk phase of the emulsion. There is no need to isolate and further purify the copolymer. Typically, the carrier will be used to form the dispersed phase in an oil-in-water emulsion. In addition to being a solvent for the polymerisation reaction to form the co-polymer, the carrier oil may also be a solvent for a benefit agent or a vehicle in which a benefit agent is dispersed. Alternatively, the carrier oil might be a benefit agent itself. Examples of suitable carrier oils include common organic solvents such as aromatic compounds such as toluene, xylene, naptha, linear or branched hydrocarbons of different chain lengths and viscosities such as mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecane, squalane, hydrogenated polyisobutylene, polybutene, polydecene, docosane, hexadecane, isohexadecane and other isoparaffins, which are branched hydrocarbons, ketones such as cyclohexanone, silicones such as polyalkylsiloxanes, polydialkylsiloxanes, polydiarylsiloxanes, and polyalkarylsiloxanes may also be used. This includes the polydimethylsiloxanes, which are commonly known as dimethicones. Further cyclic siloxanes (e.g., cyclopentasiloxane) and dimethiconoles, alkyl methicones, alkyl dimethicones, dimethicone copolyols, aminofunctional silicones (e.g. amodimethicone, trimethylsilyloxyamodimethicone) and amphoteric silicones (e.g., cetyl PEG/PPG- 5/1 butyl ether dimethicone, and bis-PEG- 18 methyl ether dimethyl silane). Alcohol, diol, triol or polyol esters of carboxylic or dicarboxylic acids, of either natural or synthetic origin having straight chain, branched chain and aryl carboxylic acids include diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, cetyl lactate, myristyl lacate, lauryl lactate, C 12 - 15 lactate, dioctyl malate, decyl oleate, isodecyl oleate, ethylene glycol distearate, ethylhexyl palmitate (octyl palmitate), isodecyl neopentanoate, tridecyl neopentanoate, castoryl maleate, isostearyl neopentanoate, di- 2- ethylhexyl maleate, cetyl palmitate, myristyl myristate, stearyl stearate, cetyl stearate, isocetyl stearate, dioctyl maleate, octyl dodecyl stearate, isocetyl stearoyl stearate, octyldodecyl stearoyl stearate dioctyl sebacate, diisopropyl adipate, cetyl octanoate, glyceryl dilaurate, diisopropyl dilinoleate and caprylic/capric triglyceride. Naturally occurring includes triglycerides, diglycerides, monoglycerides, long chain medium chain and short chain wax esters and blends of these. Examples for naturally derived ester-based oils and waxes include, but are not limited to, moringa pterygoserma seed extract, argan oil, corn oil, castor oil, coconut oil, cottonseed oil, menhaden oil, avocado oil, beeswax, carnauba wax, cocoa butter, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, rice bran oil, pine oil, sesame oil, sunflower seed oil and safflower oil. Also useful are hydrogenated, ethoxylated, propoxylated and maleated derivatives of these materials, e.g. hydrogenated safflower oil, hydrogenated castor oil and medium chain triglycerides.

Preferred carrier oils include: mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecan, docosane, hexadecane, ketones such as cyclohexanone, poly(dimethyl siloxanes), diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, ethylhexyl palmitate (octyl palmitate), palmitate, myristyl myristate, stearyl stearate, diisopropyl adipate, and caprylic/capric triglyceride. Corn oil, castor oil, coconut oil, cottonseed oil, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, pine oil, sesame oil, sunflower seed oil and safflower oil and medium chain triglycerides.

The ethylenically monounsaturated monomer

The ethylenically monounsaturated or monofunctional monomer comprises the ethylenically monounsaturated crosslinking monomer of formula I defined herein and optionally one or more additional ethylenically monounsaturated compounds which can be polymerised by an addition polymerisation mechanism, for example vinyl and allyl compounds.

The cross-linking monomer of formula I

The copolymer comprises at least one cross-linking monomer formed by the polymerisation of a monomer of Formula (1 ):

H ₂ C=CH(Ri)-C(O)-O-R2-Si(OR3)3

Formula (1 ) wherein Ri is H or an optionally substituted (1 -4C)alkyl group; R2 is a (2- 8C)alkylene group and R3 is an optionally substituted (1 -4C)alkyl group.

Suitably, Ri is H or (1 -2C)alkyl. In an embodiment, Ri is H or methyl. In a particular embodiment, Ri is H. In a further embodiment, Ri is methyl.

Suitably, R2 is a (2-4C)alkylene. In a particular embodiment, R2 is ethylene or propylene, particularly propylene. Suitably, R3 is (1 -3C)alkyl and, more suitably, R3 is (1 -2C)alkyl. In an embodiment, R3 is methyl. In an embodiment, R3 is ethyl.

Suitable tri(alkoxy)silylalkylacrylates or tri(alkoxy)silylalkyl(meth)acrylates are known in the art. Particular examples include trimethoxysilylpropylacrylate, triethoxysilylpropylacrylate, trimethoxysilylpropyl(meth)acrylate and triethoxysilylpropyl(meth)acrylate.

In an embodiment, the cross-linking monomer of formula I accounts for 10 to 100 mole % of the ethylenically monounsatu rated monomer component of the copolymer. More typically, the cross-linking monomer of formula I accounts for 30 to 100 mole % of the ethylenically monounsaturated monomer component of the copolymer. In other embodiments of the invention, the cross-linking monomer of formula I accounts for 50 to 100 mole %, or 60 to 100 mole %, or 70 to 100 mole %, or 80 to 100 mole %, or 70 to 98 mole %, or 80 to 95 mole % of the ethylenically monounsaturated monomer component of the copolymer.

The additional ethylenically monounsaturated monomer

As indicated above, the ethylenically monounsaturated monomer component may comprise, in addition to the crosslinking monomer of formula I, one or more additional ethylenically monounsaturated monomers.

The additional monounsaturated monomer or monomers may be hydrophilic, hydrophobic, amphiphilic, anionic, cationic, neutral or zwitterionic in nature. The additional monounsaturated monomers may be selected from, but not limited to, monomers such as vinyl acids, vinyl acid esters, vinyl aryl compounds, vinyl acid anhydrides, vinyl amides, vinyl ethers, vinyl amines, vinyl aryl amines, vinyl nitriles, vinyl ketones, and derivatives of the aforementioned compounds as well as corresponding allyl variants thereof. Other suitable monounsaturated monomers include hydroxyl-containing monomers and monomers which can be post-reacted to form hydroxyl groups, acid-containing or acid-functional monomers, zwitterionic monomers and quaternised amino monomers. Oligomeric, polymeric and di- or multi- functionalised monomers may also be used, especially oligomeric or polymeric (meth)acrylic acid esters such as mono(alk/aryl) (meth)acrylic acid esters of poly(alkyleneglycol) or poly(dimethylsiloxane) or any other mono-vinyl or allyl adduct of a low molecular weight oligomer. Mixtures of more than one monomer may also be used to give statistical, graft, gradient or alternating copolymers.

Vinyl acids and derivatives thereof include (meth)acrylic acid, fumaric acid, maleic acid, itaconic acid and acid halides thereof such as (meth)acryloyl chloride. Vinyl acid esters and derivatives thereof include C1-C20 alkyl(meth)acrylates (linear & branched) such as methyl (meth)acrylate, stearyl (meth)acrylate and 2-ethyl hexyl (meth)acrylate, aryl(meth)acrylates such as benzyl (meth)acrylate, tri(alkyloxy)silylalkyl(meth)acrylates such as trimethoxysilylpropyl(meth)acrylate and activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate. Vinyl aryl compounds and derivatives thereof include styrene, acetoxystyrene, styrene sulfonic acid, vinyl pyridine, vinylbenzyl chloride and vinyl benzoic acid. Vinyl acid anhydrides and derivatives thereof include maleic anhydride. Vinyl amides and derivatives thereof include (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidone, N-vinyl formamide, (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]dimethyl ammonium chloride, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide. Vinyl ethers and derivatives thereof include methyl vinyl ether. Vinyl amines and derivatives thereof include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, mono-t-butylaminoethyl (meth)acrylate, morpholinoethyl(meth)acrylate and monomers which can be post- reacted to form amine groups, such as vinyl formamide. Vinyl aryl amines and derivatives thereof include vinyl aniline, vinyl pyridine, N-vinyl carbazole and vinyl imidazole. Vinyl nitriles and derivatives thereof include (meth)acrylonitrile. Vinyl ketones and derivatives thereof include acreolin.

Hydroxyl-containing monomers include vinyl hydroxyl monomers such as hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, glycerol mono(meth)acrylate and sugar mono(meth)acrylates such as glucose mono(meth)acrylate. Monomers which can be post-reacted to form hydroxyl groups include vinyl acetate, acetoxystyrene and glycidyl (meth)acrylate. Acid-containing or acid functional monomers include (meth)acrylic acid, styrene sulfonic acid, vinyl phosphonic acid, vinyl benzoic acid, maleic acid, fumaric acid, itaconic acid, 2- (meth)acrylamido 2-ethyl propanesulfonic acid, mono-2-((meth)acryloyloxy)ethyl succinate and ammonium sulfatoethyl (meth)acrylate. Zwitterionic monomers include (meth)acryloyloxyethylphosphoryl choline and betaines, such as [2- ((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide. Quaternised amino monomers include (meth)acryloyloxyethyltri-(alk/aryl)ammonium halides such as (meth)acryloyloxyethyltrimethyl ammonium chloride.

Oligomeric and polymeric monomers include oligomeric and polymeric (meth)acrylic acid esters such as mono(alk/aryl)oxypoly(alkyleneglycol)(meth)acrylates and mono(alk/aryl)oxypoly(dimethylsiloxane)(meth)acrylates. These esters include monomethoxyoligo(ethyleneglycol) mono(meth)acrylate, monomethoxyoligo(propyleneglycol) mono(meth)acrylate, monohydroxyoligo(ethyleneglycol) mono(meth)acrylate, monohydroxyoligo(propyleneglycol) mono(meth)acrylate, monomethoxy poly(ethyleneglycol) mono(meth)acrylate, monomethoxy poly(propyleneglycol) mono(meth)acrylate, monohydroxy poly(ethyleneglycol) mono(meth)acrylate and monohydroxy poly(propyleneglycol) mono(meth)acrylate. Further examples include vinyl or allyl esters, amides or ethers of pre-formed oligomers or polymers formed via ring-opening polymerisation such as oligo(caprolactam), oligo(caprolactone), poly(caprolactam) or poly(caprolactone), or oligomers or polymers formed via a living polymerisation technique such as poly(1 ,4-butadiene).

The corresponding allyl monomers to those listed above can also be used where appropriate.

Further examples of suitable additional monounsaturated monomers are:

Amide-containing monomers such as, for example, (meth)acrylamide, N-(2- hydroxypropyl)methacrylamide, N,N'-dimethyl(meth)acrylamide, N and/or N'-di(alkyl or aryl) (meth)acrylamide, N-vinyl pyrrolidone, [3-((meth)acrylamido)propyl] trimethyl ammonium chloride, 3-(dimethylamino)propyl(meth)acrylamide, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide;

(Meth)acrylic acid and derivatives thereof such as (meth)acrylic acid, (meth)acryloyl chloride (or any halide), (alkyl/aryl)(meth)acrylate, functionalised oligomeric or polymeric monomers such as monomethoxyoligo(ethyleneglycol) mono(meth)acrylate, monomethoxyoligo(propyleneglycol) mono(meth)acrylate, monohydroxyoligo(ethyleneglycol) mono(meth)acrylate, monohydroxyoligo(propyleneglycol) mono(meth)acrylate.monomethoxy poly(ethyleneglycol) mono(meth)acrylate, monomethoxy poly(propyleneglycol) mono(meth)acrylate, monohydroxy poly(ethyleneglycol) mono(meth)acrylate, monohydroxy poly(propyleneglycol) mono(meth)acrylate, glycerol mono(meth)acrylate and sugar mono(meth)acrylates such as glucose mono(meth)acrylate; vinyl amines such as, for example, aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, mono-t-butylamino (meth)acrylate, morpholinoethyl(meth)acrylate, vinyl aryl amines such as vinyl aniline, vinyl pyridine, N-vinyl carbazole, vinyl imidazole, and monomers which can be post-reacted to form amine groups, such as N-vinyl formamide; vinyl aryl monomers such as, for example, styrene, vinyl benzyl chloride, vinyl toluene, -methyl styrene, styrene sulfonic acid and vinyl benzoic acid; vinyl hydroxyl monomers such as, for example, hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, glycerol mono(meth)acrylate or monomers which can be post- functionalised into hydroxyl groups such as vinyl acetate, acetoxy styrene and glycidyl (meth)acrylate; acid-containing monomers such as, for example, (meth)acrylic acid, styrene sulfonic acid, vinyl phosphonic acid, vinyl benzoic acid, maleic acid, fumaric acid, itaconic acid, 2-(meth)acrylamido 2-ethyl propanesulfonic acid and mono-2- ((meth)acryloyloxy)ethyl succinate or acid anhydrides such as maleic anhydride; zwitterionic monomers such as, for example, (meth)acryloyloxyethylphosphoryl choline and betaine-containing monomers, such as [2-((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide; quaternised amino monomers such as, for example, (meth)acryloyloxyethyltrimethyl ammonium chloride.

The corresponding allyl monomer, where applicable, can also be used in each case.

Functional monomers, i.e. monomers with reactive pendant groups which can be post or pre-modified with another moiety following polymerisation, or which take part in the intra- or inter-molecular cross-linking reaction to form the encapsulate wall can also be used such as glycidyl (meth)acrylate, (meth)acryloyl chloride, maleic anhydride, hydroxyalkyl (meth)acrylates, (meth)acrylic acid, vinylbenzyl chloride, activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2-isocyonatoethyl (meth)acrylate, ethyleneglycol dicyclopentenyl ether methacrylate or 5-norbornene-2-methanol methacrylate and acetoxystyrene.

Macromonomers (monomers having a molecular weight of at least 1 ,000 Daltons) are generally formed by linking a polymerisable moiety, such as a vinyl or allyl group, to a pre-formed monofunctional polymer via a suitable linking unit such as an ester, an amide or an ether. Examples of suitable polymers include mono functional poly(alkyleneglycol) such as monomethoxy poly(ethyleneglycol) or monomethoxy poly(propyleneglycol), silicones such as poly(dimethylsiloxane)s, polymers formed by ring-opening polymerisation such as poly(caprolactone) or poly(caprolactam) or mono-functional polymers formed via living polymerisation such as poly(1 ,4- butadiene).

Preferred macromonomers include monomethoxy poly(ethyleneglycol) mono(methacrylate), monomethoxy poly(propyleneglycol) mono(methacrylate) and mono(meth)acryloxypropyl-terminated poly(dimethylsiloxane).

Hydrophilic monounsaturated monomers include (meth)acryloyl chloride, N- hydroxysuccinamido (meth)acrylate, styrene sulfonic acid, maleic anhydride, (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidinone, N-vinyl formamide, quaternised amino monomers such as (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]trimethyl ammonium chloride and (meth)acryloyloxyethyltrimethyl ammonium chloride, 3-[N-(3-

(meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonat e, methyl (meth)acrylamidoglycolate methyl ether, glycerol mono(meth)acrylate, monomethoxy and monohydroxyoligo(ethyleneglycol) (meth)acrylate, sugar mono(meth)acrylates such as glucose mono(meth)acrylate, (meth)acrylic acid, vinyl phosphonic acid, fumaric acid, itaconic acid, 2-(meth)acrylamido 2-ethyl propanesulfonic acid, mono- 2-((meth)acryloyloxy)ethyl succinate, ammonium sulfatoethyl (meth)acrylate, (meth)acryloyloxyethylphosphoryl choline and betaine-containing monomers such as [2-((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide. Preferred hydrophobic monounsaturated monomers include: methyl (meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, t-butyl(meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, vinylbenzyl chloride, methyl vinyl ether, vinyl formamide, (meth)acrylonitrile, styrene.

Preferred hydrophilic monounsaturated monomers include: (meth)acrylic acid, fumaric acid, maleic acid, itaconic acid, N-hydroxysuccinamido (meth)acrylate, acetoxystyrene, styrene sulfonic acid, vinyl pyridine, and vinyl benzoic acid, maleic anhydride, (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidone, N-vinyl formamide, (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]dimethyl ammonium chloride, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, morpholinoethyl(meth)acrylate, acreolin, poly(ethyleneglycol) (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, 2-(meth)acrylamido 2-ethyl propanesulfonic acid, (meth)acryloyloxyethyltrimethyl ammonium chloride.

Preferred reactive monofunctional monomers include: trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, allyl methacrylate, ethyleneglycol dicyclopentenyl ether methacrylate or 5-norbornene-2-methanol methacrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2-isocyonatoethyl (meth)acrylate and vinylbenzyl chloride.

In an embodiment, the additional ethylenically monounsaturated monomers account for 0 to 90 mole % of the ethylenically monounsaturated monomer component of the copolymer. More typically, the additional ethylenically monounsaturated monomers will account for 0 to 70 mole % of the ethylenically monounsaturated monomer component of the copolymer. In other embodiments of the invention, the additional ethylenically monounsaturated monomers accounts for 0 to 50 mole %, or 0 to 40 mole %, or 0 to 30 mole %, or 0 to 20 mole %, or 2 to 30 mole %, or 5 to 20 mole % of the ethylenically monounsaturated monomer component of the copolymer. The ethylenically polyunsaturated monomer

The ethylenically polyunsaturated (multifunctional) monomer (also referred to herein as "brancher(s)") may comprise a molecule containing at least two vinyl groups which may be polymerised via addition polymerisation. The monomers may be hydrophilic, hydrophobic, amphiphilic, neutral, cationic, zwitterionic, oligomeric or polymeric. Such monomers are often known as cross-linking agents in the art and may be prepared by reacting any di- or multifunctional monomer with a suitably reactive monomer. Examples include di- or multivinyl esters, di- or multivinyl amides, di- or multivinyl aryl compounds, di- or multivinyl alk/aryl ethers. Typically, in the case of oligomeric or polymeric di- or multifunctional branchers, a linking reaction is used to attach a polymerisable moiety to a di- or multifunctional oligomer or polymer. The brancher may itself have more than one branching point, such as T-shaped divinylic oligomers or polymers. In some cases, more than one ethylenically polyunsaturated (multifunctional) monomer may be used.

The corresponding allyl monomers to those listed above can also be used where appropriate.

Preferred multifunctional monomers include but are not limited to: divinyl aryl monomers such as divinyl benzene; (meth)acrylate diesters such as ethylene glycol di(meth)acrylate, propyleneglycol di(meth)acrylate and 1 ,3-butylenedi(meth)acrylate; poly(alkyleneglycol) di(meth)acrylates such as tetraethyleneglycol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and poly(propyleneglycol) di(meth)acrylate; divinyl (meth)acrylamides such as methylene bisacrylamide; butanediol di(meth)acrylate, hexanediol di(meth)acrylate, silicone-containing divinyl esters or amides such as (meth)acryloxypropyl-terminated poly(dimethylsiloxane); divinyl ethers such as poly(ethyleneglycol)divinyl ether; and tri-, tetra- or hexyl- (meth)acrylate esters such as trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerithritol hexa(meth)acrylate or glucose di- to penta(meth)acrylate. Further examples include vinyl or allyl esters, amides or ethers of pre-formed oligomers or polymers formed via ring-opening polymerisation such as oligo(caprolactam), oligo(caprolactone), poly(caprolactam) or poly(caprolactone), or oligomers or polymers formed via a living polymerisation technique such as oligo- or poly(1 ,4-butadiene). Macrocross-linkers or macrobranchers (multifunctional monomers having a molecular weight of at least 1 ,000 Daltons) are generally formed by linking a polymerisable moiety, such as a vinyl or aryl group, to a pre-formed multifunctional polymer via a suitable linking unit such as an ester, an amide or an ether. Examples of suitable polymers include di-functional poly(alkylene oxides) such as poly(ethyleneglycol) or poly(propyleneglycol), silicones such as poly(dimethylsiloxane)s, polymers formed by ring-opening polymerisation such as poly(caprolactone) or poly(caprolactam) or poly-functional polymers formed via living polymerisation such as poly(1 ,4-butadiene).

Preferred macrobranchers include poly(ethyleneglycol) di(meth)acrylate, poly(propyleneglycol) di(meth)acrylate, methacryloxypropyl-terminated poly(dimethylsiloxane), poly(caprolactone) di(meth)acrylate and poly(caprolactam) di(meth)acrylamide.

Branchers include methylene bisacrylamide, glycerol di(meth)acrylate, glucose di- and tri(meth)acrylate, oligo(caprolactam) and oligo(caprolactone). Multi end- functionalised hydrophilic polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group.

Further branchers include divinyl benzene, (meth)acrylate esters such as, for example, ethyleneglycol di(meth)acrylate, propyleneglycol di(meth)acrylate and 1 ,3- butylene di(meth)acrylate, oligo(ethylene glycol) di(meth)acrylates such as tetraethylene glycol di(meth)acrylate, tetra- or tri- (meth)acrylate esters such as pentaerthyritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylateand glucose penta(meth)acrylate. Multi end-functionalised hydrophobic polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group.

Multifunctional responsive polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group such as polypropylene oxide) di(meth)acrylate.

Preferred polyunsaturated monomers or branchers include: divinyl benzene, ethyleneglycol di(meth)acrylate, 1 ,4 butanediol di(methacrylate), hexane diol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and N, N'- methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and dipentaerithritol hexa(meth)acrylate.

The molar ratio of ethylenically polyunsaturated monomer component to the ethylenically monounsaturated monomer component is 1 :100 to 1 :4. More typically, the molar ratio of ethylenically polyunsaturated monomer component to the ethylenically monounsaturated monomer component is 1 :20 to 1 :4, or 1 :20 to 1 :5.

The chain transfer agent (CTA) and initiator

The chain transfer agent (CTA) is a molecule which is known to reduce molecular weight during a free-radical polymerisation via a chain transfer mechanism. These agents may be any thiol-containing molecule and can be either monofunctional or multifunctional. The agent may be hydrophilic, hydrophobic, amphiphilic, anionic, cationic, neutral, zwitterionic or responsive. The agent can also be an oligomer or a pre-formed polymer containing a thiol moiety. The agent may also be a hindered alcohol or similar free-radical stabiliser such as 2, 4-diphenyl-4-methyl-1 -pentene. Catalytic chain transfer agents, such as those based on transition metal complexes, e.g. cobalt bis(borondifluorodimethyl-glyoximate) (CoBF) may also be used. Suitable thiols include but are not limited to C2-C18 alkyl thiols such as dodecane thiol, thioglycolic acid, thioglycerol, cysteine and cysteamine. Thiol-containing oligomers or polymers may also be used, such as poly(cysteine) or an oligomer or polymer which has been post-functionalised to give a thiol group(s), such as poly(ethyleneglycol) (di)thio glycollate, or a pre-formed polymer functionalised with a thiol group, for example, reaction of an end or side-functionalised alcohol such as polypropylene glycol) with thiobutyrolactone, to give the corresponding thiol-functionalised chain- extended polymer. Multifunctional thiols may also be prepared by the reduction of a xanthate, dithioester or trithiocarbonate end-functionalised polymer prepared via a Reversible Addition Fragmentation Transfer (RAFT) or Macromolecular Design by the Interchange of Xanthates (MADIX) living radical method. Xanthates, dithioesters, and dithiocarbonates may also be used, such as cumyl phenyldithioacetate. Alternative chain transfer agents may be any species known to limit the molecular weight in a free-radical addition polymerisation including alkyl halides and transition metal salts or complexes. More than one chain transfer agent may be used in combination. When the chain transfer agent is providing the necessary hydrophilicity in the copolymer, it is preferred that the chain transfer agent is hydrophilic and has a molecular weight of at least 1 ,000 Daltons.

Where the polymer is comprised of primarily hydrophilic monomers and branchers it is preferred that the CTA is a hydrophobic compound. Hydrophobic CTAs include but are not limited to linear and branched alkyl and aryl (di)thiols such as dodecanethiol, octadecyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3- mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9- nonanedithiol and 2,4-diphenyl-4-methyl-1 -pentene. Hydrophobic macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from hydrophobic polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed hydrophobic polymer can be post functionalised with a compound such as thiobutyrolactone.

Hydrophilic CTAs typically contain hydrogen bonding and/or permanent or transient charges. Hydrophilic CTAs include but are not limited to thio-acids such as thioglycolic acid and cysteine, thioamines such as cysteamine and thio-alcohols such as 2-mercaptoethanol, 3-mercaptopropanoic acid, thioglycerol and ethylene glycol mono- (and di-)thio glycollate. Hydrophilic macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from hydrophilic polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed hydrophilic polymer can be post functionalised with a compound such as thiobutyrolactone.

Responsive macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from responsive polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed responsive polymer, such as polypropylene glycol), can be post functionalised with a compound such as thiobutyrolactone.

The residue of the chain transfer agent may comprise 0 to 80 mole %, preferably 0 to 50 mole %, more preferably 0 to 40 mole % and especially 0.05 to 30 mole %, of the copolymer (based on the number of moles of monounsaturated monomer). The initiator is a free-radical initiator and can be any molecule known to initiate free- radical polymerisation such as azo-containing molecules, persulfates, redox initiators, peroxides, phenyl benzyl ketones. These may be activated via thermal, photolytic or chemical means. Examples of these include but are not limited to azo- compounds e.g. 2,2'-azobisisobutyronitrile (AIBN), azobis(4-cyanovaleric acid) or peroxides such as benzoyl peroxide, and the Luperox® range from Arkema such as di-t-butyl peroxide (Luperox® Dl), t-butyl peroxybenzoate, (Luperox® P), dicumylperoxide (Luperox® DCP), di-t-amyl peroxide (Luperox® DTA), 1 - hydroxycyclohexyl phenyl ketone, hydrogenperoxide/ascorbic acid. Iniferters such as benzyl-N,N-diethyldithiocarbamate can also be used. In some cases, more than one initiator may be used. The initiator may be a macroinitiator having a molecular weight of at least 1 ,000 Daltons. In this case, the macroinitiator may be hydrophilic, hydrophobic, or responsive.

Preferably, the residue of the initiator in a free-radical polymerisation comprises 0 to 40% w/w, preferably 0.01 to 30% w/w and especially 0.01 to 20% w/w, of the copolymer based on the total weight of the monomers.

The use of a chain transfer agent and an initiator is preferred. However, some molecules can perform both functions.

Hydrophilic macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from hydrophilic polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use in Atom Transfer Radical Polymerisation (ATRP) with a suitable low valency transition metal catalyst, such as CuBr Bipyridyl.

Hydrophobic macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from hydrophobic polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use with ATRP.

Responsive macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from responsive polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use with ATRP.

Preferred chain transfer agents include: dodecanethiol, octadecyl mercaptan, 2- ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3-mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9-nonanedithiol and 2,4-diphenyl-4- methyl-1 -pentene.

Preferred initiators include: 2,2'-azobisisobutyronitrile (AIBN), azobis(4-cyanovaleric acid), and compounds from the Luperox® range from Arkema such as benzoyl peroxide, di-t-butyl peroxide (Luperox® Dl), t-butyl peroxybenzoate, (Luperox® P), dicumylperoxide (Luperox® DCP), di-t-amyl peroxide (Luperox® DTA), 1 - hydroxycyclohexyl phenyl ketone and hydrogenperoxide/ascorbic acid.

Reaction conditions for the addition polymerisation

The addition polymerisation process proceeds via a solution polymerisation wherein the reactants, monomer(s), brancher(s), chain transfer agent(s) and initiator(s), are added to a solvent, the carrier oil, and polymerisation proceeds through initiation. It is preferred that the reactants are soluble in the carrier oil at the reaction temperature although they can also be dispersed in the carrier oil, likewise it is preferred that the addition copolymer product is also soluble in the carrier oil at the reaction temperature although the addition copolymer product can also be dispersed within the medium following polymerisation. The solids content of the polymerisation process can be from 0.5 % to 90 % w/w, preferably between 5 % and 80 % w/w and especially between 10 and 70 % w/w.

The polymerisation can proceed via a batch process wherein all of the components are added to the reaction vessel at the start of the polymerisation process and the addition copolymer product isolated in the carrier oil following reaction. The polymerisation can also take place via a feed proceed whereby the reactants are added continuously throughout the polymerisation process from one or more separate source vessels, this can be done in such a way as the monomers are consumed uniformly during the polymerisation process to avoid monomer build-up, so-called accumulation. Additionally it is preferred in this case that the initiator is added separately in order to cease the reaction by stopping the initiator feed, if required, this process is known in the art as a starved-feed polymerisation and is common in solution or emulsion polymerisation processes. In this case the reactants can be added neat to the carrier oil or more preferably added as solutions or dispersions within the carrier oil.

This process can also be performed where a portion of the reaction solution is added to the vessel at the start of the process, typically around 20 to 30 % and the remaining constituents are added throughout the process, so-called semi-batch process. Following the addition of the reactants the polymerisation can be allowed to proceed for a period of time, in some instances an additional aliquot of initiator can be added to consume any free monomer that may be present.

The initiation of the polymerisation can occur through thermal means or via electromagnetic radiation such as ultra violet light or gamma rays, such as from a Co-60 source, or through chemical means such as a REDOX reaction with an oxidant or reducing agent and an appropriate initiator. The reaction can also proceed in a flow or tubular reactor where the reactants are passed through a tubular vessel with a designated polymerisation zone, usually a heated section with a temperature gradient, and the reactants are obtained after a set residence time. In this process the polymerisation solution can also be re-circulated until the appropriate degree of polymerisation is obtained.

In a batch, fed or semi-batch process the reaction vessel can be glass, mild steel, stainless steel, glass-lined or Hastelloy in construction and fitted with appropriate heating sources such as an oil or steam-heated jacket and cooling such as a condenser or cooling coils externally or internally fitted on or in the vessel. Where necessary the reactants can be dosed into the vessel manually or via gravity or metered pumps. It is preferred that the reaction proceeds at atmospheric pressure although higher pressures can be used with lower boiling point reactants or carrier oils.

It is preferred that the polymerisation reaction occurs at a temperature of 60 to 180 °C. The reaction time can be between 3 hours to 48 hours, preferably 5 to 24 hours. The carrier oil / co-polymer composition

The process of the present invention forms the co-polymers as defined above in situ within a carrier oil. This carrier oil / co-polymer composition can then be used directly in an emulsification process, as defined further herein.

Typically, the co-polymer will be present in an amount of between 0.5 to 90 % w/w preferably 5 to 80 % w/w and especially 10 to 70 % w/w.

In addition to the co-polymers of the present invention, the carrier oil may further comprise one or more benefit agents either dissolved or dispersed in the carrier oil.

In an alternative embodiment, the carrier oil itself is a benefit agent.

Any suitable benefit agent may be used. For example, the benefit agent may include fragrances, UV absorbers, emollient oils, insecticides, phase change materials, dyes, pigments, detergents, printing inks, perfumes, silicone conditioners, shampoos, biocides, adhesives, corrosion inhibitors, anti-fouling agents, flavours, cosmetic actives, oxidizing agents, personal care actives, medicines, agrochemicals, fertilizers, fats, oils, nutrients, enzymes, liquid crystals, paints, rustproofing agents, recording materials, catalysts, chemical reactants and magnetic substances or combination thereof can be used directly or dissolved or dispersed in the oily substance as used herein depending on the purpose of use.

Fragrances include, for example, compounds which impart or mask odours for homecare, personal care and industrial uses such as alcohols, esters, terpenes, terpenoids, aromatic compounds, thiols and amines from natural or synthetic sources and include linalool, coumarin, geraniol, citral, limonene, citronellol, eugenol, cinnamal, cinnamyl alcohol, benzyl salicylate, menthol, menthyl lactate, eucalyptol, thymol, methyl salicylate, methylfuran, menthone, cinnamaldehyde. Typical representative examples of essential oils include, but are not limited to oils of orange, lavender, peppermint, lemon, pine, rosemary, rose, jasmine, tea tree, lemon grass, bergamot, basil, spearmint, juniper, clove, aniseed, fennel, cypress, fir, black pepper, sandalwood, cedarwood, rosewood, cardamom, cinnamon, corander, eucalyptus, geranium, ginger, chamomile, grapefruit, neroli, petitgrain, thyme, vetiver and ylang ylang.

Chemical and physical sunscreens/UV filters include, for example, ethylhexyl-4- methoxycinnamate, 3-benzylidene camphor, 4- methylbenzylidene camphor, aminobenzoic acid, Avobenzone, Benzophenone 4 (Sulisobenzone), Benzophenone 5, Benzophenone 8, Benzophenone-3, Benzylidene camphor sulfonic acid, Bis- ethylhexyloxyphenol methoxyphenol triazine (Escalol S), butyl methoxy dibenzoylmethane, camphor benzalkonium methosulfate, Cinoxate, diethylamino hydroxybenzoyl hexyl benzoate, dioxybenzone, disodium phenyl dibenzimidazole tetrasulfonate, Drometrizole trisi loxane, Ensulizole, ethylhexyl dimethyl PABA, Ethylhexyl methoxycinnamate, ethylhexyl salicylate, ethylhexyl triazone, Homosalate, isoamyl p-methoxycinnamate, Meradimate, menthyl anthranilate, methylene bis-benzotriazolyltetramethylbutylphenol /Bisoctrizole (Tinosorb M), Octocrylene, Octinoxate, PEG-25 PABA, Octisalate, Oxybenzone, Padimate O, Phenylbenzimidazole sulfonic acid, Polyacrylamidomethyl Benzylidene Camphor, Polysilicone- 15, TEA-salicylate, Terephthalylidene dicamphor sulfonic acid, titanium dioxide, Trolamine Salicylate and zinc oxide.

Hair treatment materials include, for example, cationic conditioning agents comprising tertiary and quaternary amino groups (e.g., quaternium-70, quaternium- 80, stearylamidopropyl dimethylamine, behentrimonium methosulfate, dicocodimonium chloride, dicetyldimonium chloride, distearyldimonium chloride hydroxyethyl cetyldimonium phosphate). In addition, they also may include UV and colour protectants (e.g., dimethylpabamidopropyl laurdimonium tosylate), heat protectants and styling polymers (e.g., vinyl pyrrolidone and vinylcaprolactam derivatives, such as PVP vinyl Caprolactam/DMAPA Acrylates Copolymer).

Antimicrobial agents may include, for example, Triclosan™, climbazole, octapyrox, ketoconazole, propiconazole, phthalimoperoxyhexanoic acid (PAP) and quaternary ammonium compounds.

Biocides may include, for example, herbicides such as glyphosphate (N- phosphonomethylglycine), Fomesafen, Glufosinate, Paraquat dichloride and Bentazone.

Fungicides may include, for example, benzimidazole compounds such as benomyl, carbendazim, thiabendazole and thiophanate-methyl; phenylcarbamate compounds such as diethofencarb; dicarboxyimide compounds such as procymidone, iprodione and vinclozolin; azole compounds such as diniconazole, epoxyconazole, tebuconazole, difenoconazole, cyproconazole, flusilazole, flutriafol and triadimefon; acylalanine compounds such as metalaxyl; carboxyamide compounds such as furametpyr, mepronil, flutolanil and tolyfluanid; organophosphate compounds such as tolclofos-methyl, fosetyl aluminum and pyrazophos; anilinopyrimidine compounds such as pyrimethanil, mepanipyrim and cyprodinil; cyanopyrrrole compounds such as fludioxonil and fenpiclonil; antibiotics such as blasticidin-S, kasugamycin, polyoxin and validamycin; methoxyacrylate compounds such as azoxystrobin, kresoxim- methyl and metominostrobin; chlorothalonil; manzeb; captan; folpet; tricyclazole; pyroquilon; probenazole; phthalide; cymoxanil; dimethomorph; S-methylbenzo [ 1 , 2, 3] thiadiazol-7- carbothioate; famoxadone; oxolinic acid; fluaziname; ferimzone; chlobenthiazone; isovaledione; tetrachloroisophthalonitrile; thiophthalimideoxybisphenoxyarsine; 3-iodo-2- propylbutylcarbamate; parahydroxy benzoic ester. Preferred water-insoluble biocides for use in the present invention are antibacterials (for example chlorophenols including Triclosan), antifungals (for example organochlorines including Chlorothalonil and imidazoles such as Ketoconazole and Propiconazole), insecticides (for example pyrethroids, including λ- cyhalothrin) and/or herbicides (for example phenol-ureas including Isoproturon). The invention is also envisaged to be applicable to acaricides, algicides, molluscicides and nematacides.

Nutrient compounds may include, for example, omega oils and fish oils which can give a nutritional or cosmetic benefit such as omega-3, omega-6 and omega-9 fatty acids docosapentaenoic acid, eicosatetraenoic acid, moroctic acid, heneicosapentenoic acid, cod liver oil, halibut liver oil, herring oil, menhaden oil, salmon or trout oils, sardine oil, tuna oil or shark liver oils. Vitamin A and vitamin E.

Insect repellents may include, for example, N,N-dimethyl-m-toluamine (DEET), citronella oil, p-menthane, 3-8-diol, metofluthrin and ethyl 3- [acetyl(butyl)amino]propionate.

Antidandruff agents may include, for example, zinc pyrithione and/or resorcinol monoacetate

Skin lightening agents may include, for example, 4-ethylresorcinol.

Fluorescing agents may include, for example, 2,5-bis(2-benzoxazolyl) thiophene for use on fabrics (such as cotton, nylon, polycotton or polyester) in laundry products. Skin conditioning agents may include, for example, cholesterol, 3,5,4'-trihydroxy- trans-stilbene (Reservatrol), di-benzoyl peroxide (for acne treatment),

Antifoaming agents may include, for example, isoparrafin and silicone-containing compounds.

Phase change materials, which are compounds which can store and release heat by a phase change in the materials. Examples of these include waxes, such as paraffin waxes, inorganic salts, such as sodium acetate and liquid crystalline materials.

The benefit agent can be present within the carrier oil at between 0.1 to 100 %

Particularly preferred benefit agents include:

Fragrances and flavours including esters, alcohols, amides, terpenes, aromatic compounds, amines, terpenes, aldehydes, ketones from natural and synthetic sources. Particular fragrance components would be those used widely in the homecare, personal care and industrial applications. The fragrances would typically be present as a mixture of top notes, mid notes and base notes formulated to provide a spectrum of odours.

Applications of the co-polymer / carrier oil compositions

The co-polymer is formed in a carrier oil as defined above. The resultant co-polymer / carrier oil composition can be used directly to form an emulsion.

Thus, in a fourth aspect, the present invention provides an emulsion formed by emulsifying a carrier oil composition as defined in the third aspect of the present invention, or as formed by the process of the first aspect of the invention with an aqueous phase.

In a fifth aspect, the present invention provides a process for forming an emulsion as defined in the fourth aspect of the invention, the process comprising: providing a carrier oil comprising a statistical branched amphiphilic copolymer, wherein said polymer is formed within the carrier oil as defined above in relation to the first aspect of the invention; providing an aqueous phase; emulsifying the carrier oil and aqueous phases to form an emulsion

The carrier oil phase or aqueous phase may comprise a benefit agent.

In an embodiment, the emulsion is an oil-in-water emulsion and the carrier oil is the dispersed phase and either is, or comprises, a benefit agent.

In an alternative embodiment, the emulsion is a water-in-oil emulsion and the carrier oil forms the bulk phase. In such embodiments, the aqueous phase may be, or may comprise, a benefit agent.

The carrier oil compositions formed by the first aspect of the invention may also be used to form polymer capsules that encapsulate the dispersed phase of the emulsion by the formation of covalent cross-links between the co-polymer molecules.

Thus, in a sixth aspect, the present invention provides a process for forming a polymer capsule, the process comprising: providing a carrier oil comprising a statistical branched amphiphilic copolymer, wherein said polymer is formed within the carrier oil as defined above in relation to the first aspect of the invention; providing an aqueous phase; emulsifying the carrier oil and aqueous phases to form an emulsion; and facilitating the cross-linking of the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the aqueous phase and the carrier oil.

In addition, in a seventh aspect, the present invention provides a polymer capsule obtainable by, obtained by, directly obtained by, or formed by, a process as defined in the sixth aspect of the invention.

The carrier oil and aqueous phase in any of the aforementioned aspects of the invention may be emulsified by any suitable emulsification technique known in the art. For example, the emulsion may be prepared using any common equipment known in the art for this purpose, such as, for example, high shear mixers, homogenisers, ultrasound, membrane emulsification, or microfluidics. A person skilled in the art will understand how to vary the properties of the emulsion by varying equipment used, the shear forces applied, the agitation time etc. A person skilled in the art will also be able to vary the amount of the copolymer defined herein in order to provide the desired level of stabilisation to the emulsion droplets.

To form polymeric capsules, the process of the sixth aspect of the invention requires an additional step whereby the cross-linking of the copolymers of the present invention is facilitated. Typically, the cross-linking will occur by the reaction of the alkoxysilyl moieties of Formula I on adjacent copolymer molecules to form crosslinks. This is commonly known as a sol-gel process.

The branched addition copolymers of the current invention tend to stabilise the emulsions in the pre-capsule formation to a better degree than chemically analogous linear copolymers, by function of their higher molecular weight and increased end- groups and branched architecture. This therefore can lead to better capsule formation in the crosslinking step as it reduces the requirement to complete the cross-linking step in a specific time period, that is the emulsions do not have to be cross-linked immediately as in the case for the linear copolymer encapsulating agents, additionally the branched polymers are synthesised in the carrier medium to be emulsified and encapsulated.

The formation of these cross-links may be facilitated by allowing the emulsion to stand for a period of time, optionally at neutral pH. However, the reaction can be catalysed by the addition of either an acid or a base such as sulfuric, hydrochloric, phosphoric acid or a compound which hydrolyses itself to give an acidic moiety such as δ-gluconolactone or an alkali hydroxide, carbonate or bicarbonate such as sodium hydroxide, sodium carbonate or sodium bicarbonate at pH ranges from 2 to 13. Preferably the emulsion is crosslinked through a change in pH and via a sol-gel reaction of the trialkoxysilyl moieties present in the copolymer.

The particle size of the polymer capsules can be controlled by controlling the size of the emulsion droplets. This can be achieved by techniques known in the art such as varying the production parameters (e.g. agitation speeds, times, temperatures) and the composition of the emulsion (the amount of emulsifier, the nature of the different phases etc.). Preferably the average size of the capsules is smaller than 100 μιη, more preferably smaller than 50 μιη. Preferably the polymer capsule has an internal oil phase and is formed in an aqueous bulk phase. In a preferred embodiment the capsule comprises a benefit agent, wherein the benefit agent is incorporated in the dispersed phase.

In an embodiment, the carrier oil is the dispersed phase and cross-linking of the copolymers forms polymeric capsules encapsulating the dispersed phase.

The polymeric capsule may be configured to release the encapsulated benefit agent in a controlled manner over a period of time or, alternatively, it might be configured to release the encapsulated benefit agent in a more immediate (e.g. a "burst" or "rupture" release profile) manner.

The invention also provides a method of preparing a capsule, comprising a step wherein the copolymer/carrier oil composition incorporating a benefit agent or agent(s) is mixed with a hydrophobic liquid under conditions whereby at least one of the monounsaturated monomer(s) and polyunsaturated monomer(s) and chain transfer agent do not form a non-covalent bond with any other of the monounsaturated monomer(s) and polyunsaturated monomer(s) and chain transfer agent. Under these conditions the polymer is in a non-interacting form. The capsule can be then used to protect or isolate the active agent from the final formulation or to deliver the benefit agent to the desired locus of action by, for example, a "rupture" or "burst release" mechanism.

Additional emulsifiers may also be used in the emulsification processes described herein. For example, the amphiphilic addition copolymers of the current invention can also be used in combination with non-functional small molecule or polymeric emulsifiers. In such cases, an emulsion prepared in accordance with the present invention may comprise the cross-linkable copolymer emulsifiers of the invention together with a non-reactive emulsifier. Capsule formation occurs via the cross- linking of the copolymers of this invention. This is of particular advantage where further functionality needs to be introduced in a capsule via the use of, for example, a non-functional emulsifier. Additionally, the cost of preparing the capsules can be reduced by the use of commodity surfactants or emulsifiers with only minimal changes to existing formulation procedures being required.

The polymeric capsules formed can be further post-modified with reagents to provide, for example, increased stability or surface recognition. Reactive links can be introduced into the cross-linked structure in order to facilitate rupturing of the capsules in response to certain environmental conditions, for example via a change in temperature, ionic strength or pH. Similarly, the capsules can be cross-linked together to give higher order structures such as "beads" or monoliths where the emulsion droplets have been aggregated prior to the final cross-linking step. Once formed, the contents of the capsules can also be removed by a washing material to obtain hollow receptacles suitable for filling with other benefit agent materials, or for use in their own right in for example composites where they could be utilised as an additive to alter the opacity, dielectric constant or strength of a composite, coating or film.

In embodiments where the branched addition copolymers have associating functionality, such as H-bonding groups, they may aggregate in solution upon the application of an external trigger such as in the case of capsules decorated with carboxylic acid functionality. In this case, the formed capsules may assemble via hydrogen-bonding (with inherent changes in hydrophobicity) when below the pKa of the acid group and reversibly disassemble upon the application of an increase in pH.

The encapsulation of hydrophobic benefit agents is of industrial relevance where a hydrophobic component is required to be delivered from, formulated in or isolated from an aqueous environment. For example the cross-linked capsule may protect a benefit agent compound from a hydrophilic formulation where the bulk aqueous environment can lead to degradation of the hydrophobic material or is, for example, rich in additional surfactants which can affect the performance of the hydrophobic benefit agent. The capsule may also be post-modified in order to improve the selectivity of the capsule, such as the covalent attachment of surface-substantive or bio-active materials, for example in the specific delivery of pharmaceutical agents. The capsules may also be designed to assemble and disassemble upon changes in the aqueous environment, such as pH, this is particularly desirable in the preparation of a "capsule concentrate" in the associated form for transportation purposes and formulation dilution at the required destination, that is On-site'. The payload of the capsule can also be washed-out to yield hollow spheroids which can be filled or used in their own right as, for example, in composite materials. Examples include but are not limited to: the encapsulation of bioactive compounds such as pharmaceuticals or agrochemicals; nutritional agents such as vitamins; cosmetics, catalysts, dyes, pigments, flavours, fragrances, lubricating oils, emollients, natural oils and waxes, paints, inks, coatings, sealants and tissue engineering scaffolds.

Particular embodiments

The following numbered paragraphs 1 ) to 41 ) are not claims, but instead describe particular embodiments of aspects 1 to 7 of the invention:

1 ) A method of preparing a statistical branched amphiphilic copolymer in a carrier oil, wherein the branched copolymer comprises: at least two chains which are covalently linked by a bridge other than at their ends; and wherein the at least two chains are formed by the polymerisation of one or more ethylenically monounsatu rated monomers and the bridge is formed by the polymerisation of one or more ethylenically polyunsaturated monomers; and wherein:

(i) the one or more ethylenically monounsatu rated monomers comprise one or more crosslinking monomers of Formula (1 ):

H ₂ C=CH(Ri)-C(O)-O-R2-Si(OR3)3

Formula (1 ) wherein Ri is H or an optionally substituted (1 -4C)alkyl group; R2 is a (2- 8C)alkylene group and R3 is an optionally substituted (1 -4C)alkyl group; and optionally one or more additional ethylenically monounsaturated monomers;

(ii) the copolymer comprises the residue of chain transfer agent and/or an initiator;

(iii) at least one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophilic residue, and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophobic residue; and

(iv) the mole ratio of polyunsaturated monomer(s) to monounsaturated monomer(s) is from 1 :100 to 1 :4; and wherein said copolymer is formed by an addition polymerisation process, which comprises mixing together:

(a) the one or more ethylenically monounsaturated monomers;

(b) from 1 to 25 mole% (based on the number of moles of monounsaturated monomer(s)) of the one or more ethylenically polyunsaturated monomers;

(c) a chain transfer agent; and

(d) an initiator; in a carrier oil and subsequently reacting said mixture to form the statistical branched amphiphilic copolymer.

2) A method according to numbered paragraph 1 , wherein the concentration of the statistical branched amphiphilic copolymer in the carrier oil is 0.5 % to 90 % w/w.

3) A method according to numbered paragraph 2, wherein the concentration of the statistical branched amphiphilic copolymer in the carrier oil is 5 % to 80 % w/w.

4) A method according to any one of the preceding numbered paragraphs, wherein the carrier oil has a boiling point above 100 °C.

5) A method according to any one of the preceding numbered paragraphs, wherein the carrier oil is selected from the group consisting of mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecan, docosane, hexadecane, ketones such as cyclohexanone, poly(dimethyl siloxanes), diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, ethylhexyl palmitate (octyl palmitate), palmitate, myristyl myristate, stearyl stearate, diisopropyl adipate, and caprylic/capric triglyceride. Corn oil, castor oil, coconut oil, cottonseed oil, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, pine oil, sesame oil, sunflower seed oil, safflower oil and medium chain triglycerides.

6) A method according to any one of the preceding numbered paragraphs, wherein in the ethylenically monounsaturated crosslinking monomer of formula I, Ri is H or (1 -2C)alkyl; R ₂ is a (2-4C)alkylene; and Ra is (1 -3C)alkyl. 7) A method according to any one of the preceding numbered paragraphs, wherein in the ethylenically monounsaturated crosslinking monomer of formula I, Ri is H or methyl; R2 is ethylene or propylene; and R3 is (1 -2C)alkyl.

8) A method according any one of the preceding numbered paragraphs, wherein the crosslinking monomer of formula I is selected from trimethoxysilylpropylacrylate, triethoxysilylpropylacrylate, trimethoxysilylpropylmethacrylate and

triethoxysilylpropylmethacrylate.

9) A method according to any one of the preceding numbered paragraphs, wherein the crosslinking monomer of formula I accounts for 10 to 100 mole% of the ethylenically monounsaturated monomer component of the copolymer.

10) A method according to numbered paragraph 9, wherein the crosslinking monomer of formula I accounts for 60 to 100 mole% of the ethylenically monounsaturated monomer component of the copolymer.

1 1 ) A method according to any one of the preceding numbered paragraphs, wherein the polymer further comprises one or more additional ethylenically monounsaturated monomers in addition to the crosslinking monomer of formula I.

12) A method according to any one of the preceding numbered paragraphs, wherein the one or more additional ethylenically monounsaturated monomers account for 0 to 90 mole% of the ethylenically monounsaturated monomer component of the copolymer.

13) A method according to numbered paragraph 12, wherein the one or more additional ethylenically monounsaturated monomers account for 0 to 40 mole% of the ethylenically monounsaturated monomer component of the copolymer.

14) A method according to any one of the preceding numbered paragraphs, wherein the ethylenically polyunsaturated monomer is selected from the group consisting of divinyl benzene, ethyleneglycol di(meth)acrylate, 1 ,4 butanediol di(methacrylate), hexane diol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and N, N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and dipentaerithritol hexa(meth)acrylate.

15) A method according to any one of the preceding numbered paragraphs, wherein the molar ratio of the ethylenically polyunsaturated monomer component to the ethylenically monounsaturated monomer component of the co-polymer is 1 :50 to 1 :4.

16) A method according to any one of the preceding numbered paragraphs, wherein the molar ratio of the ethylenically polyunsaturated monomer component to the ethylenically monounsaturated monomer component of the co-polymer is 1 :20 to 1 :4.

17) A method according to any one of the preceding numbered paragraphs, wherein the chain transfer agent (CTA) is a hydrophobic compound.

18) A method according to numbered paragraph 17, wherein the hydrophobic CTA is selected from linear and branched alkyl and aryl (di)thiols (e.g. dodecanethiol, octadecyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3- mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9- nonanedithiol and 2,4-diphenyl-4-methyl-1 -pentene).

19) A method according to any one of the preceding numbered paragraphs, wherein the chain transfer agent (CTA) is a hydrophilic compound.

20) A method according to numbered paragraph 19, wherein the hydrophilic CTA is selected from thio-acids (e.g. thioglycolic acid and cysteine), thioamines (e.g. cysteamine) and thio-alcohols (e.g. 2-mercaptoethanol, 3-mercaptopropanoic acid, thioglycerol and ethylene glycol mono- (and di-)thio glycollate).

21 ) A method according to any one of the preceding numbered paragraphs, wherein the chain transfer agent (CTA) is present at 0 to 80 mole % (based on the number of moles of monounsaturated monomer).

22) A method according to any one of the preceding numbered paragraphs, wherein the chain transfer agent (CTA) is present at 0 to 50 mole % (based on the number of moles of monounsaturated monomer).

23) A method according to any one of the preceding numbered paragraphs, wherein the initiator is a free-radical initiator.

24) A method according to any one of the preceding numbered paragraphs, wherein the initiator is present in an amount of 0.01 to 40% w/w.

25) A method according to any one of the preceding numbered paragraphs, wherein the initiator is present in an amount of 0.01 to 15% w/w. 26) A method according to any one of the preceding numbered paragraphs, wherein the initiator is selected from 2,2'-azobisisobutyronitrile (AIBN), azobis(4- cyanovaleric acid), and compounds from the Luperox® range from Arkema such as benzoyl peroxide, di-t-butyl peroxide (Luperox® Dl), t-butyl peroxybenzoate, (Luperox® P), dicumylperoxide (Luperox® DCP), di-t-amyl peroxide (Luperox® DTA), 1 -hydroxycyclohexyl phenyl ketone and hydrogenperoxide/ascorbic acid.

27) A method according to any one of the preceding numbered paragraphs, wherein the polymerisation reaction proceeds at an elevated temperature of 60 to 180 °C.

28) A method according to any one of the preceding numbered paragraphs, wherein the polymerisation reaction proceeds for between 3 to 48 hours.

29) A statistical branched amphiphilic copolymer in a carrier oil obtainable by a method according to any one of numbered paragraphs 1 to 28.

30) A composition comprising a statistical branched amphiphilic copolymer obtainable by a method according to any one of numbered paragraphs 1 to 28 in a carrier oil.

31 ) A composition according to numbered paragraph 30, wherein the statistical branched amphiphilic copolymer is present at an amount of 0.5 to 90 % w/w in the carrier oil.

32) A composition according to numbered paragraph 31 , wherein the statistical branched amphiphilic copolymer is present at an amount of 5 to 80 % w/w in the carrier oil.

33) A composition according to any one of numbered paragraphs 30 to 32, wherein the carrier oil further comprises one or more benefit agents.

34) A composition according to any one of numbered paragraphs 30 to 32, wherein the carrier oil is a benefit agent.

35) An emulsion formed by emulsifying a carrier oil composition as defined in numbered paragraphs 30 to 34 with an aqueous phase.

36) An emulsion according to numbered paragraph 35, wherein the emulsion is an oil-in-water emulsion. 37) An emulsion according to numbered paragraph 35, wherein the emulsion is a water-in-oil emulsion.

38) A process for forming an emulsion as defined in any one of numbered paragraphs 35 to 37, the process comprising: providing a carrier oil comprising a statistical branched amphiphilic copolymer, wherein said polymer is formed within the carrier oil as defined in numbered paragraphs 1 to 28; providing an aqueous phase; and emulsifying the carrier oil and aqueous phases to form an emulsion.

39) A process for forming a polymer capsule, the process comprising: providing a carrier oil comprising a statistical branched amphiphilic copolymer, wherein said polymer is formed within the carrier oil as defined in numbered paragraphs 1 to 28; providing an aqueous phase; emulsifying the carrier oil and aqueous phases to form an emulsion; and facilitating the cross-linking of the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the aqueous phase and the carrier oil.

40) A process according to numbered paragraph 39, wherein the cross-linking of the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the aqueous phase and the carrier oil is facilitated by the addition of an acid or a base to the aqueous phase.

41 ) A polymer capsule obtainable by a process as defined in numbered paragraph 39 or 40.

ASPECTS 8 AND 9 OF THE INVENTION Process for preparing the polymeric capsules

The present invention provides a method of preparing a polymeric capsule, the process comprising: providing a mixture comprising an oil phase, an aqueous phase, a statistical branched amphiphilic copolymer emulsifier, a first polymensable species present in the oil phase, a second polymerisable species present in the aqueous phase, wherein said first and second polymerisable species can react with one another to form a polymer; emulsifying the mixture to form an emulsion having a dispersed phase and a continuous phase; and

Forming a polymeric capsule around the dispersed phase by the reaction between the first and second polymerisable species at the oil/water interface.

The process of the present invention enables polymeric capsules to be formed around the dispersed phase of the emulsion in a simple and efficient manner. The properties of the resultant polymeric capsules can also be tuned by varying the properties of the emulsion, the nature of the copolymer emulsifier used as well as the first and second polymerisable species and then nature and properties of the polymer they form.

In an embodiment, the emulsion is an oil-in-water emulsion and the oil phase forms the dispersed phase.

In an alternative embodiment, the emulsion is a water-in-oil emulsion and the aqueous phase is the dispersed phase.

It is also possible to form double emulsions (i.e. water-in-oil-in-water or oil-in-water- in-oil emulsions).

Additional emulsifiers (in addition to the statistical branched amphiphilic copolymer) may be used in the process of the present invention as necessary.

The oil phase

Any suitable oil phase can be used in the process of the present invention.

In an embodiment, the oil phase is a carrier oil. The term "carrier oil" is used herein to refer to an organic or "oil" phase having a boiling point of greater than 80 °C. Typically, the carrier oil will have a boiling point of greater than 100°C, more typically greater than 120°C and most typically greater than 130°C. Such carrier oils are generally considered to be non-volatile liquids at ambient temperature and pressure. Any suitable carrier oil could be used.

Examples of suitable carrier oils include common organic solvents such as aromatic compounds such as toluene, xylene, naptha, linear or branched hydrocarbons of different chain lengths and viscosities such as mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecane, squalane, hydrogenated polyisobutylene, polybutene, polydecene, docosane, hexadecane, isohexadecane and other isoparaffins, which are branched hydrocarbons, ketones such as cyclohexanone, silicones such as polyalkylsiloxanes, polydialkylsiloxanes, polydiarylsiloxanes, and polyalkarylsiloxanes may also be used. This includes the polydimethylsiloxanes, which are commonly known as dimethicones. Further cyclic siloxanes (e.g., cyclopentasiloxane) and dimethiconoles, alkyl methicones, alkyl dimethicones, dimethicone copolyols, aminofunctional silicones (e.g. amodimethicone, trimethylsilyloxyamodimethicone) and amphoteric silicones (e.g., cetyl PEG/PPG- 5/1 butyl ether dimethicone, and bis-PEG- 18 methyl ether dimethyl silane). Alcohol, diol, triol or polyol esters of carboxylic or dicarboxylic acids, of either natural or synthetic origin having straight chain, branched chain and aryl carboxylic acids include diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, cetyl lactate, myristyl lacate, lauryl lactate, C 12 - 15 lactate, dioctyl malate, decyl oleate, isodecyl oleate, ethylene glycol distearate, ethylhexyl palmitate (octyl palmitate), isodecyl neopentanoate, tridecyl neopentanoate, castoryl maleate, isostearyl neopentanoate, di- 2- ethylhexyl maleate, cetyl palmitate, myristyl myristate, stearyl stearate, cetyl stearate, isocetyl stearate, dioctyl maleate, octyl dodecyl stearate, isocetyl stearoyl stearate, octyldodecyl stearoyl stearate dioctyl sebacate, diisopropyl adipate, cetyl octanoate, glyceryl dilaurate, diisopropyl dilinoleate and caprylic/capric triglyceride. Naturally occurring includes triglycerides, diglycerides, monoglycerides, long chain medium chain and short chain wax esters and blends of these. Examples for naturally derived ester-based oils and waxes include, but are not limited to, argan oil, corn oil, castor oil, coconut oil, cottonseed oil, menhaden oil, avocado oil, beeswax, carnauba wax, cocoa butter, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, rice bran oil, pine oil, sesame oil, sunflower seed oil and safflower oil. Also useful are hydrogenated, ethoxylated, propoxylated and maleated derivatives of these materials, e.g. hydrogenated safflower oil, hydrogenated castor oil and medium chain triglycerides.

Preferred carrier oils include: mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecan, docosane, hexadecane, ketones such as cyclohexanone, poly(dimethyl siloxanes), diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, ethylhexyl palmitate (octyl palmitate), palmitate, myristyl myristate, stearyl stearate, diisopropyl adipate, and caprylic/capric triglyceride. Corn oil, castor oil, coconut oil, cottonseed oil, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, pine oil, sesame oil, sunflower seed oil and safflower oil and medium chain triglycerides.

Suitably, the oil phase comprises the statistical branched amphiphilic copolymer defined hereinbefore. Typically, the copolymer will be present in an amount of between 0.5 to 90 % w/w preferably 5 to 80 % w/w and especially 10 to 70 % w/w in the carrier oil.

The oil phase may also be a solvent for a benefit agent or a vehicle in which a benefit agent is dispersed. Alternatively, the oil phase might be a benefit agent itself.

The oil phase also serves as the solvent for the first polymerisable species.

The oil phase may optionally further comprise the crosslinking agent as defined ehrein at an amount of 0.1 to 40 % by weight of the amphiphilic branched copolymer. In an embodiment, the cross-linking agent is present at an amount of 0.5 to 30 % by weight of the amphiphilic branched copolymer. In a further embodiment, the cross- linking agent is present at an amount of 1 to 20 % by weight of the amphiphilic branched copolymer.

The aqueous phase

Any suitable aqueous medium may be used as the aqueous phase in the emulsion process.

Typically, the aqueous phase will be the continuous phase, but in certain embodiments of the invention, the emulsion may be a water-in-oil emulsion and the aqueous phase will be the dispersed phase. In embodiments where the aqueous phase is the dispersed phase, the aqueous phase may be, or may further comprise, a benefit agent.

The aqueous phase is the solvent for the second polymerisable species.

The aqueous phase may further comprise additional additives, such as, for example, one or more additional stabilisers, viscosity modifiers, or pH modifying agents (e.g. an acid, a base or a buffer system).

Benefit agents

Any suitable benefit agent may be used in the process of the present invention.

For example, the benefit agent may include fragrances, UV absorbers, emollient oils, insecticides, phase change materials, dyes, pigments, detergents, printing inks, perfumes, silicone conditioners, shampoos, biocides, adhesives, corrosion inhibitors, anti-fouling agents, flavours, cosmetic actives, oxidizing agents, personal care actives, medicines, agrochemicals, fertilizers, fats, oils, nutrients, enzymes, liquid crystals, paints, rustproofing agents, recording materials, catalysts, chemical reactants and magnetic substances or combination thereof can be used directly or dissolved or dispersed in the oily substance as used herein depending on the purpose of use.

Fragrances include, for example, compounds which impart or mask odours for homecare, personal care and industrial uses such as alcohols, esters, terpenes, terpenoids, aromatic compounds, thiols and amines from natural or synthetic sources and include linalool, coumarin, geraniol, citral, limonene, citronellol, eugenol, cinnamal, cinnamyl alcohol, benzyl salicylate, menthol, menthyl lactate, eucalyptol, thymol, methyl salicylate, methylfuran, menthone, cinnamaldehyde. Typical representative examples of essential oils include, but are not limited to oils of orange, lavender, peppermint, lemon, pine, rosemary, rose, jasmine, tea tree, lemon grass, bergamot, basil, spearmint, juniper, clove, aniseed, fennel, cypress, fir, black pepper, sandalwood, cedarwood, rosewood, cardamom, cinnamon, corander, eucalyptus, geranium, ginger, chamomile, grapefruit, neroli, petitgrain, thyme, vetiver and ylang ylang. Chemical and physical sunscreens/UV filters include, for example, ethylhexyl-4- methoxycinnamate, 3-benzylidene camphor, 4- methylbenzylidene camphor, aminobenzoic acid, Avobenzone, Benzophenone 4 (Sulisobenzone), Benzophenone 5, Benzophenone 8, Benzophenone-3, Benzylidene camphor sulfonic acid, Bis- ethylhexyloxyphenol methoxyphenol triazine (Escalol S), butyl methoxy dibenzoylmethane, camphor benzalkonium methosulfate, Cinoxate, diethylamino hydroxybenzoyl hexyl benzoate, dioxybenzone, disodium phenyl dibenzimidazole tetrasulfonate, Drometrizole trisi loxane, Ensulizole, ethylhexyl dimethyl PABA, Ethylhexyl methoxycinnamate, ethylhexyl salicylate, ethylhexyl triazone, Homosalate, isoamyl p-methoxycinnamate, Meradimate, menthyl anthranilate, methylene bis-benzotriazolyltetramethylbutylphenol /Bisoctrizole (Tinosorb M), Octocrylene, Octinoxate, PEG-25 PABA, Octisalate, Oxybenzone, Padimate O, Phenylbenzimidazole sulfonic acid, Polyacrylamidomethyl Benzylidene Camphor, Polysilicone- 15, TEA-salicylate, Terephthalylidene dicamphor sulfonic acid, titanium dioxide, Trolamine Salicylate and zinc oxide.

Hair treatment materials include, for example, cationic conditioning agents comprising tertiary and quaternary amino groups (e.g., quaternium-70, quaternium- 80, stearylamidopropyl dimethylamine, behentrimonium methosulfate, dicocodimonium chloride, dicetyldimonium chloride, distearyldimonium chloride hydroxyethyl cetyldimonium phosphate). In addition, they also may include UV and colour protectants (e.g., dimethylpabamidopropyl laurdimonium tosylate), heat protectants and styling polymers (e.g., vinyl pyrrolidone and vinylcaprolactam derivatives, such as PVP vinyl Caprolactam/DMAPA Acrylates Copolymer).

Antimicrobial agents may include, for example, Triclosan™, climbazole, octapyrox, ketoconazole, propiconazole, phthalimoperoxyhexanoic acid (PAP) and quaternary ammonium compounds.

Biocides may include, for example, herbicides such as glyphosphate (N- phosphonomethylglycine), Fomesafen, Glufosinate, Paraquat dichloride and Bentazone.

Fungicides may include, for example, benzimidazole compounds such as benomyl, carbendazim, thiabendazole and thiophanate-methyl; phenylcarbamate compounds such as diethofencarb; dicarboxyimide compounds such as procymidone, iprodione and vinclozolin; azole compounds such as diniconazole, epoxyconazole, tebuconazole, difenoconazole, cyproconazole, flusilazole, flutriafol and triadimefon; acylalanine compounds such as metalaxyl; carboxyamide compounds such as furametpyr, mepronil, flutolanil and tolyfluanid; organophosphate compounds such as tolclofos-methyl, fosetyl aluminum and pyrazophos; anilinopyrimidine compounds such as pyrimethanil, mepanipyrim and cyprodinil; cyanopyrrrole compounds such as fludioxonil and fenpiclonil; antibiotics such as blasticidin-S, kasugamycin, polyoxin and validamycin; methoxyacrylate compounds such as azoxystrobin, kresoxim- methyl and metominostrobin; chlorothalonil; manzeb; captan; folpet; tricyclazole; pyroquilon; probenazole; phthalide; cymoxanil; dimethomorph; S-methylbenzo [ 1 , 2, 3] thiadiazol-7- carbothioate; famoxadone; oxolinic acid; fluaziname; ferimzone; chlobenthiazone; isovaledione; tetrachloroisophthalonitrile; thiophthalimideoxybisphenoxyarsine; 3-iodo-2- propylbutylcarbamate; parahydroxy benzoic ester. Preferred water-insoluble biocides for use in the present invention are antibacterials (for example chlorophenols including Triclosan), antifungals (for example organochlorines including Chlorothalonil and imidazoles such as Ketoconazole and Propiconazole), insecticides (for example pyrethroids, including λ- cyhalothrin) and/or herbicides (for example phenol-ureas including Isoproturon). The invention is also envisaged to be applicable to acaricides, algicides, molluscicides and nematacides.

Nutrient compounds may include, for example, omega oils and fish oils which can give a nutritional or cosmetic benefit such as omega-3, omega-6 and omega-9 fatty acids docosapentaenoic acid, eicosatetraenoic acid, moroctic acid, heneicosapentenoic acid, cod liver oil, halibut liver oil, herring oil, menhaden oil, salmon or trout oils, sardine oil, tuna oil or shark liver oils. Vitamin A and vitamin E.

Insect repellents may include, for example, N,N-dimethyl-m-toluamine (DEET), citronella oil, p-menthane, 3-8-diol, metofluthrin and ethyl 3- [acetyl(butyl)amino]propionate.

Antidandruff agents may include, for example, zinc pyrithione and/or resorcinol monoacetate

Skin lightening agents may include, for example, 4-ethylresorcinol. Fluorescing agents may include, for example, 2,5-bis(2-benzoxazolyl) thiophene for use on fabrics (such as cotton, nylon, polycotton or polyester) in laundry products.

Skin conditioning agents may include, for example, cholesterol, 3,5,4'-trihydroxy- trans-stilbene (Reservatrol), di-benzoyl peroxide (for acne treatment),

Antifoaming agents may include, for example, isoparrafin and silicone-containing compounds.

Phase change materials, which are compounds which can store and release heat by a phase change in the materials. Examples of these include waxes, such as paraffin waxes, inorganic salts, such as sodium acetate and liquid crystalline materials.

Particularly preferred benefit agents include:

Fragrances and flavours including esters, alcohols, amides, terpenes, aromatic compounds, amines, terpenes, aldehydes, ketones from natural and synthetic sources. Particular fragrance components would be those used widely in the homecare, personal care and industrial applications. The fragrances would typically be present as a mixture of top notes, mid notes and base notes formulated to provide a spectrum of odours.

The benefit agent can be present within the carrier oil or aqueous phase at a concentration of between 0.1 to 100 % w/w. Typically, the emulsion will be an oil-in- water emulsion and the benefit agent will be present in the oil phase.

The statistical branched amphiphilic copolymer

The process of the present invention uses a statistical branched amphiphilic copolymer as an emulsifier.

These copolymers are statistical, that is to say, random in structure. The distribution of the comonomers in the polymer structure is not controlled and is determined through factors such as the relative monomer concentrations and their respective reactivity ratios. This negates the requirement to use controlled polymerisation techniques that are required to achieve, for example, block copolymer structures or to control their molecular weights or polydispersities. Additionally, the copolymers are formed by a conventional free-radical polymerisation process. The copolymer may, in some instances, be prepared directly within the oil phase without the need for any further purification. This can negate the requirement to prepare the copolymers in another solvent and then isolate and purify the copolymer. Instead, the first polymerisable species may be added to the copolymer/oil phase composition along with any benefit agent payload and then directly emulsified with the aqueous phase. This process can also be used where the benefit agent is a liquid in which the copolymer can be directly synthesised, thereby removing a number of steps from the industrial process.

The statistical branched amphiphilic copolymers used in the process of the present invention are effective emulsifiers. In some embodiments, the copolymer stabilises the emulsion droplets that are formed and can then be crosslinked by the reaction of functional groups present on adjacent copolymer molecule, either directly or via a reaction with a separate crosslinking agent, in order to form a polymeric capsules or shells around the dispersed emulsion droplets, effectively encapsulating the dispersed emulsion droplets (and any benefit agent that is contained therein). It will be appreciated that any capsule or shell formed by the crosslinking of the statistical branched amphiphilic copolymer will be in addition to the polymer capsule formed by the interfacial polymerisation reaction of the first and second polymerisable species.

The emulsions stabilised may be oil-in-water or water-in-oil, or so-called double emulsions (water-in-oil-in-water or oil-in-water-in-oil emulsions). Typically, the emulsion will be an oil-in-water emulsion.

The copolymers are amphiphilic addition copolymers. Amphiphilic addition copolymers are especially useful for stabilising oil-in-water emulsions. In particular branched copolymers are especially useful as they have been shown to form extremely stable emulsions at low concentrations due to their high molecular weight, branched architectures and chemical composition. These branched copolymers effectively stabilise oil-in-water emulsions more effectively than equivalent linear polymers.

The amphiphilic copolymers are branched. The branched, non-crosslinked addition amphiphilic copolymers may include statistical, graft, gradient and alternating branched copolymers. The copolymers typically comprise at least two chains which are covalently linked by a bridge other than at their ends, which is to be understood as a polymer wherein a sample of said polymer comprises on average at least two chains which are covalently linked by a bridge other than at their ends. When a sample of the copolymer is prepared, there may be accidentally some copolymer molecules which are unbranched, which is inherent to the production method (addition polymerisation process). For the same reason, a small quantity of the polymer will not have a chain transfer agent at a chain end.

To function in the desired manner, the statistical branched amphiphilic copolymer must have certain attributes as discussed further below.

Amphiphilicity: The addition copolymer must be amphiphilic, i.e. it must contain moieties capable of associating with the dispersed (internal) and continuous (bulk) phases of the emulsion. Thus, the copolymer must contain hydrophilic and hydrophobic units within the copolymer structure. Hydrophobicity is typically achieved by using hydrophobic monomers, such as alkyl-functional monomers, e.g. an alkyl methacrylate, and/or via a hydrophobic chain transfer agent such as an alkyl mercaptan, e.g. dodecanethiol. Additionally, the copolymer must have hydrophilic functionality, again typically achieved by the use of hydrophilic monomers, for example the monomer could be neutral, for example poly(ethylene glycol)-functional monomers such as mono-methoxypoly(ethylene glycol) methacrylate, or the monomer could be charged in nature, such as acrylic or methacrylic acid or weakly basic monomers, e.g. dimethyl or diethylaminoethyl methacrylate or their respective salts. The hydrophilic unit can be responsive in nature whereby the hydrophilicity can be altered by an external stimulus such as pH or temperature, such as in the case of N-isopropylacrylamide. The hydrophilic and hydrophobic units could also be introduced through the ethylenically polyunsaturated monomer (brancher) or chain transfer agent where applicable.

In an embodiment, the hydrophilic monomer may be of high molecular weight, such that at least one of the ethylenically monounsatu rated monomer, the ethylenically polyunsaturated monomer and/or the chain transfer agent is a hydrophilic residue having a molecular weight of at least 400 Daltons (e.g. at least 1 ,000 Daltons). In an embodiment, the hydrophilic component is derived from the ethylenically polyunsaturated monomer. In another embodiment, the hydrophilic component is the chain transfer agent. In a preferred embodiment, the hydrophilic component is the ethylenically monounsatu rated monomer. In all cases, a combination of hydrophilic components is possible and may be desirable. Higher molecular weight hydrophobic species are typically more hydrophobic than lower molecular weight hydrophobic species. Preferably, the hydrophobic component is derived from the polyunsaturated monomer, more preferably from the chain transfer agent (during conventional free-radical polymerisation) or the initiator, but most preferably from a monounsaturated monomer. In all cases, a combination of hydrophobic components is possible and may be desirable.

Branched addition copolymers: Branched copolymers are polymer molecules of a finite size which are branched. Branched polymers are soluble and differ from crosslinked polymer networks which tend towards an infinite size having interconnected molecules and which are generally not soluble but often swellable. In some instances, branched polymers have advantageous properties when compared to analogous linear polymers. For instance, solutions of soluble branched polymers are normally less viscous than solutions of analogous linear polymers. Moreover, higher molecular weights of branched copolymers can be solubilised more easily than those of corresponding linear polymers. Also, branched copolymers tend to have more end groups than a linear polymer and therefore generally exhibit strong surface-modification properties. Thus, branched copolymers are useful components of many compositions utilised in a variety of fields.

Branched polymers are usually prepared via a step-growth mechanism through the polycondensation of monomers and are usually limited via the chemical functionality of the resulting polymer and the molecular weight. In an addition polymerisation process, a one-step process can be used in which a multifunctional monomer is used to provide functionality in the polymer chain from which polymer branches may grow.

The statistical branched amphiphilic copolymers in the present invention are typically soluble materials, that is they form isotropic solutions in hydrophilic or hydrophobic solvents, which have been designed to emulsify hydrophobic or hydrophilic materials in an aqueous or hydrophobic bulk medium.

Branched addition amphiphilic copolymers have been shown to be efficient emulsifiers, especially for oil-in-water emulsions. Thus, the copolymers will typically be used to emulsify a hydrophobic oil in an aqueous bulk phase. Essentially the branched addition copolymer must be capable of forming a stable emulsion which can then allow the first and second polymerisable species to react to form a polymeric shell or capsule.

Functionality: As indicated above, in some embodiments functional groups present on the copolymer can also react with function groups present on adjacent copolymer molecules or a cross linking agent to further contribute to the polymeric capsule formed by the first and second polymerisable species. In an embodiment, this functionality is achieved by the inclusion of alkoxysilane functional groups, which react with other alkoxysilane functional groups present on adjacent copolymer molecules and/or the crosslinking agent via a sol-gel process. However, other functional groups may be present in place of, or in addition to the alkoxysilane functional groups, including those which can form intermolecular ester, amide, urethane, urea linkages or those associated by a nucleophilic substitution or addition reactions, for example the reaction of an epoxide with a nucleophile such as an amine or an alkoxide which can occur through the reaction of a residue of glycidyl(meth)acrylate with an amine residue derived from aminoethyl(meth)acrylate or the reaction of a benzyl halide moiety such as a residue derived from a vinylbenzyl chloride monomer with an amine moiety such as that derived from a residue from a dimethylamino ethyl (methacrylate) monomer or via reactions with an acetoacetate functionality such as that obtained from a residue of 2- (methacrylyoxy)ethyl acetoacetate.

In such embodiments, the copolymer acts as both emulsifier and an additional polymeric capsule former. Additionally, the emulsion or polymer capsule can be further chemically reacted post-emulsification, or post-encapsulation, to give further chemical species at the surface of the emulsion or polymer capsule which may be of benefit, for example in improved substrate affinity. Crosslinking can occur between copolymer residues on the same interface to form capsules or between copolymer emulsifiers on adjacent interfaces to form monoliths.

The statistical branched amphiphilic copolymer suitably comprises at least two polymeric chains which are covalently linked by a bridge. The at least two chains are typically formed by the polymerisation of one or more ethylenically monounsaturated monomers and the bridge or bridges is/are formed by the polymerisation of at least one ethylenically polyunsaturated monomer. In certain embodiments, the copolymer also comprises one or more functional groups capable of reacting with functional groups present on adjacent copolymer molecule and/or a separate crosslinking agent and thereby form a capsule or shell at the interface between the oil phase and the aqueous phase.

Typically, the statistical branched amphiphilic copolymer further comprises a residue of a chain transfer agent and optionally a residue of an initiator.

Suitably, at least one of the monounsatu rated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophilic residue; and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophobic residue.

Suitably, the mole ratio of polyunsaturated monomer(s) to monounsaturated monomer(s) is 1 :100 to 1 :4.

It will be appreciated that a number of different functional groups may be present on the copolymer and the selection of suitable reactive functional groups capable of reacting with functional groups present on other co-polymer molecules or a crosslinking agent will be readily apparent to a person skilled in the art. For example, the copolymer may comprise functional groups capable of reacting with a crosslinking agent by a variety of different reaction chemistries such as, for example, nucleophilic substitution, electrophilic addition, ring-opening reactions, sol-gel reactions (such as the reaction between di-tri-or poly alkoxy silanes), Diels-Alder reactions, ester formation, amide formation, urethane formation, urea formation, carbonate formation, thiol-ene formation, addition polymerisation (from the polymerisation of unreacted or pendant groups on the amphiphilic branched copolymer with an additional monomer or di-or poly-functional monomer) and the 1 + 3 Huisgen cycloaddition reaction, so-called "click chemistry". Thus, the copolymer may, for example, comprise one or more functional groups capable of reacting with functional groups on a crosslinking agent or other copolymer molecules to form ester, amide, urethane, urea or thiol linkages, or other linkages associated with a nucleophilic substitution or addition reactions, for example the reaction of an epoxide with a nucleophile such as an amine or an alkoxide (which can occur through the reaction of a residue of glycidyl(meth)acrylate with an amine residue derived from aminoethyl(meth)acrylate or the reaction of a benzyl halide moiety such as a residue derived from a vinylbenzyl chloride monomer with an amine moiety such as that derived from a residue from a dimethylamino ethyl (methacrylate) monomer. Thus, suitable functional groups may be selected from amines, alcohols, thiols, ketones, carboxylic acids, acid chlorides, halogens, alkoxysilanes, epoxides, and acetoacetates.

In a particular embodiment, the reaction between di- or tri-functional alkoxysilanes present on the copolymer with di-, tri- or tetra-alkoxysilanes present in crosslinking agent are preferred. To facilitate such a reaction, monomers bearing pendant alkoxysilyl groups may be incorporated in the amphiphilic branched copolymer structure. These alkoxysilyl groups are typically (1 -2C)alkoxysilyl groups. These moieties may react with suitable additional crosslinking agents, including tri- and tetra-alkoxysilanes such as tetramethyl orthosilicate and tetraethyl orthosilicate, sodium silicate, bis(triethoxysilyl)ethane, bis(trimethoxyethyl)silane, tris-[3- (trimethoxysilyl)propyl]isocyanurate, tris-[3-(triethoxysilyl)propyl]isocyanurate, mercapropropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-octanoylthio-1 - propyl triethoxysilane, aminopropyl trialkoxysilanes such as aminopropyltrimethoxy silane or aminopropyl triethoxysilane, aminopropyl methyl diethoxysilane, Ν-(β- aminoethyl)-Y-aminopropyl trimethoxysilane, N-[N'-(2-aminoethyl)aminoethyl]-3- aminopropyl trimethoxysilane, N-phenyl aminopropyl trimethoxysilane, N-ethyl- aminoisobutyl trimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, ureidopropyl trimethoxysilane, isocyanatopropyl triethoxysilane, isocyanatopropyl trimethoxysilane, glycidoxypropyl trimethoxysilane, glycidoxypropyl triethoxysilane, 3,4 - epoxycyclohexyl - ethyl trimethoxysilane and 3,4 - epoxycyclohexyl - ethyl triethoxysilane.

In an embodiment, the copolymer comprises one or more alkoxysilane groups which are capable of reacting with alkoxysilane groups present on adjacent co-polymer molecules or on a crosslinking agent via a sol-gel process.

The ethylenically monounsaturated monomer

The ethylenically monounsaturated or monofunctional monomer may be any suitable monounsaturated monomer known in the art.

The ethylenically monounsaturated monomer or monomers may be hydrophilic, hydrophobic, amphiphilic, anionic, cationic, neutral or zwitterionic in nature. The monounsaturated monomers may be selected from, but not limited to, monomers such as vinyl acids, vinyl acid esters, vinyl aryl compounds, vinyl acid anhydrides, vinyl amides, vinyl ethers, vinyl amines, vinyl aryl amines, vinyl nitriles, vinyl ketones, and derivatives of the aforementioned compounds as well as corresponding allyl variants thereof. Other suitable monounsaturated monomers include hydroxyl- containing monomers and monomers which can be post-reacted to form hydroxyl groups, acid-containing or acid-functional monomers, zwitterionic monomers and quaternised amino monomers. Oligomeric, polymeric and di- or multi-functionalised monomers may also be used, especially oligomeric or polymeric (meth)acrylic acid esters such as mono(alk/aryl) (meth)acrylic acid esters of poly(alkyleneglycol) or poly(dimethylsiloxane) or any other mono-vinyl or allyl adduct of a low molecular weight oligomer. Mixtures of more than one monomer may also be used to give statistical, graft, gradient or alternating copolymers.

Vinyl acids and derivatives thereof include (meth)acrylic acid, fumaric acid, maleic acid, itaconic acid and acid halides thereof such as (meth)acryloyl chloride. Vinyl acid esters and derivatives thereof include C1-C20 alkyl(meth)acrylates (linear & branched) such as methyl (meth)acrylate, stearyl (meth)acrylate and 2-ethyl hexyl (meth)acrylate, aryl(meth)acrylates such as benzyl (meth)acrylate, tri(alkyloxy)silylalkyl(meth)acrylates such as trimethoxysilylpropyl(meth)acrylate and activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate. Vinyl aryl compounds and derivatives thereof include styrene, acetoxystyrene, styrene sulfonic acid, vinyl pyridine, vinylbenzyl chloride and vinyl benzoic acid. Vinyl acid anhydrides and derivatives thereof include maleic anhydride. Vinyl amides and derivatives thereof include (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidone, N-vinyl formamide, (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]dimethyl ammonium chloride, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide. Vinyl ethers and derivatives thereof include methyl vinyl ether. Vinyl amines and derivatives thereof include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, mono-t-butylaminoethyl (meth)acrylate, morpholinoethyl(meth)acrylate and monomers which can be post- reacted to form amine groups, such as vinyl formamide. Vinyl aryl amines and derivatives thereof include vinyl aniline, vinyl pyridine, N-vinyl carbazole and vinyl imidazole. Vinyl nitriles and derivatives thereof include (meth)acrylonitrile. Vinyl ketones and derivatives thereof include acreolin.

Hydroxyl-containing monomers include vinyl hydroxyl monomers such as hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, glycerol mono(meth)acrylate and sugar mono(meth)acrylates such as glucose mono(meth)acrylate. Monomers which can be post-reacted to form hydroxyl groups include vinyl acetate, acetoxystyrene and glycidyl (meth)acrylate. Acid-containing or acid functional monomers include (meth)acrylic acid, styrene sulfonic acid, vinyl phosphonic acid, vinyl benzoic acid, maleic acid, fumaric acid, itaconic acid, 2- (meth)acrylamido 2-ethyl propanesulfonic acid, mono-2-((meth)acryloyloxy)ethyl succinate and ammonium sulfatoethyl (meth)acrylate. Zwitterionic monomers include (meth)acryloyloxyethylphosphoryl choline and betaines, such as [2- ((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide. Quaternised amino monomers include (meth)acryloyloxyethyltri-(alk/aryl)ammonium halides such as (meth)acryloyloxyethyltrimethyl ammonium chloride.

Oligomeric and polymeric monomers include oligomeric and polymeric (meth)acrylic acid esters such as mono(alk/aryl)oxypoly(alkyleneglycol)(meth)acrylates and mono(alk/aryl)oxypoly(dimethylsiloxane)(meth)acrylates. These esters include monomethoxyoligo(ethyleneglycol) mono(meth)acrylate, monomethoxyoligo(propyleneglycol) mono(meth)acrylate, monohydroxyoligo(ethyleneglycol) mono(meth)acrylate, monohydroxyoligo(propyleneglycol) mono(meth)acrylate, monomethoxy poly(ethyleneglycol) mono(meth)acrylate, monomethoxy poly(propyleneglycol) mono(meth)acrylate, monohydroxy poly(ethyleneglycol) mono(meth)acrylate and monohydroxy poly(propyleneglycol) mono(meth)acrylate. Further examples include vinyl or allyl esters, amides or ethers of pre-formed oligomers or polymers formed via ring-opening polymerisation such as oligo(caprolactam), oligo(caprolactone), poly(caprolactam) or poly(caprolactone), or oligomers or polymers formed via a living polymerisation technique such as poly(1 ,4-butadiene).

The corresponding allyl monomers to those listed above can also be used where appropriate. Further examples of suitable additional monounsaturated monomers are:

Amide-containing monomers such as, for example, (meth)acrylamide, N-(2- hydroxypropyl)methacrylamide, N,N'-dimethyl(meth)acrylamide, N and/or N'-di(alkyl or aryl) (meth)acrylamide, N-vinyl pyrrolidone, [3-((meth)acrylamido)propyl] trimethyl ammonium chloride, 3-(dimethylamino)propyl(meth)acrylamide, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide;

(Meth)acrylic acid and derivatives thereof such as (meth)acrylic acid, (meth)acryloyl chloride (or any halide), (alkyl/aryl)(meth)acrylate, functionalised oligomeric or polymeric monomers such as monomethoxyoligo(ethyleneglycol) mono(meth)acrylate, monomethoxyoligo(propyleneglycol) mono(meth)acrylate, monohydroxyoligo(ethyleneglycol) mono(meth)acrylate, monohydroxyoligo(propyleneglycol) mono(meth)acrylate.monomethoxy poly(ethyleneglycol) mono(meth)acrylate, monomethoxy poly(propyleneglycol) mono(meth)acrylate, monohydroxy poly(ethyleneglycol) mono(meth)acrylate, monohydroxy poly(propyleneglycol) mono(meth)acrylate, glycerol mono(meth)acrylate and sugar mono(meth)acrylates such as glucose mono(meth)acrylate; vinyl amines such as, for example, aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, mono-t-butylamino (meth)acrylate, morpholinoethyl(meth)acrylate, vinyl aryl amines such as vinyl aniline, vinyl pyridine, N-vinyl carbazole, vinyl imidazole, and monomers which can be post-reacted to form amine groups, such as N-vinyl formamide; vinyl aryl monomers such as, for example, styrene, vinyl benzyl chloride, vinyl toluene, -methyl styrene, styrene sulfonic acid and vinyl benzoic acid; vinyl hydroxyl monomers such as, for example, hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, glycerol mono(meth)acrylate or monomers which can be post- functionalised into hydroxyl groups such as vinyl acetate, acetoxy styrene and glycidyl (meth)acrylate; acid-containing monomers such as, for example, (meth)acrylic acid, styrene sulfonic acid, vinyl phosphonic acid, vinyl benzoic acid, maleic acid, fumaric acid, itaconic acid, 2-(meth)acrylamido 2-ethyl propanesulfonic acid and mono-2- ((meth)acryloyloxy)ethyl succinate or acid anhydrides such as maleic anhydride; zwitterionic monomers such as, for example, (meth)acryloyloxyethylphosphoryl choline and betaine-containing monomers, such as [2-((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide; quaternised amino monomers such as, for example, (meth)acryloyloxyethyltrimethyl ammonium chloride.

The corresponding allyl monomer, where applicable, can also be used in each case.

Functional monomers, i.e. monomers with reactive pendant groups which can be post or pre-modified with another moiety following polymerisation, or which take part in the intra- or inter-molecular crosslinking reaction to form the encapsulate wall can also be used such as glycidyl (meth)acrylate, (meth)acryloyl chloride, maleic anhydride, hydroxyalkyl (meth)acrylates, (meth)acrylic acid, vinylbenzyl chloride, activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2-isocyonatoethyl (meth)acrylate, ethyleneglycol dicyclopentenyl ether methacrylate or 5-norbornene-2-methanol methacrylate, 2-(methacrylyoxy)ethyl acetoacetate and acetoxystyrene.

Macromonomers (monomers having a molecular weight of at least 1 ,000 Daltons) are generally formed by linking a polymerisable moiety, such as a vinyl or allyl group, to a pre-formed monofunctional polymer via a suitable linking unit such as an ester, an amide or an ether. Examples of suitable polymers include mono functional poly(alkyleneglycol) such as monomethoxy poly(ethyleneglycol) or monomethoxy poly(propyleneglycol), silicones such as poly(dimethylsiloxane)s, polymers formed by ring-opening polymerisation such as poly(caprolactone) or poly(caprolactam) or mono-functional polymers formed via living polymerisation such as poly(1 ,4- butadiene).

Preferred macromonomers include monomethoxy poly(ethyleneglycol) mono(methacrylate), monomethoxy poly(propyleneglycol) mono(methacrylate) and mono(meth)acryloxypropyl-terminated poly(dimethylsiloxane).

Hydrophilic monounsaturated monomers include (meth)acryloyl chloride, N- hydroxysuccinamido (meth)acrylate, styrene sulfonic acid, maleic anhydride, (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidinone, N-vinyl formamide, quaternised amino monomers such as (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]trimethyl ammonium chloride and (meth)acryloyloxyethyltrimethyl ammonium chloride, 3-[N-(3-

(meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonat e, methyl (meth)acrylamidoglycolate methyl ether, glycerol mono(meth)acrylate, monomethoxy and monohydroxyoligo(ethyleneglycol) (meth)acrylate, sugar mono(meth)acrylates such as glucose mono(meth)acrylate, (meth)acrylic acid, vinyl phosphonic acid, fumaric acid, itaconic acid, 2-(meth)acrylamido 2-ethyl propanesulfonic acid, mono- 2-((meth)acryloyloxy)ethyl succinate, ammonium sulfatoethyl (meth)acrylate, (meth)acryloyloxyethylphosphoryl choline and betaine-containing monomers such as [2-((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide.

Preferred hydrophobic monounsaturated monomers include: methyl (meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, t-butyl(meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, vinylbenzyl chloride, methyl vinyl ether, vinyl formamide, (meth)acrylonitrile, styrene.

Preferred hydrophilic monounsaturated monomers include: (meth)acrylic acid, fumaric acid, maleic acid, itaconic acid, N-hydroxysuccinamido (meth)acrylate, acetoxystyrene, styrene sulfonic acid, vinyl pyridine, and vinyl benzoic acid, maleic anhydride, (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidone, N-vinyl formamide, (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]dimethyl ammonium chloride, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, morpholinoethyl(meth)acrylate, acreolin, poly(ethyleneglycol) (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, 2-(meth)acrylamido 2-ethyl propanesulfonic acid, (meth)acryloyloxyethyltrimethyl ammonium chloride.

Preferred reactive monofunctional monomers include: trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, allyl methacrylate, ethyleneglycol dicyclopentenyl ether methacrylate or 5-norbornene-2-methanol methacrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2-isocyonatoethyl (meth)acrylate and vinylbenzyl chloride.

In an embodiment, the ethylenically monounsaturated or monofunctional monomer component comprises one or more monomers that bear one or more functional groups capable of reacting with the crosslinking agent to crosslink the copolymer molecules at the oil/water interface of the emulsion.

In an embodiment, the monounsaturated monomer component comprises one or more monomers comprising a functional alkoxysilane moiety that is capable of reacting with a functional alkoxysilane moiety present on the crosslinking agent.

In a particular embodiment, the copolymer comprises one or more monounsaturated crosslinking monomers formed by the polymerisation of a monomer of Formula (1 ):

H ₂ C=CH(Ri)-C(O)-O-R2-Si(OR3)3

Formula (1 )

wherein Ri is H or an optionally substituted (1 -4C)alkyl group; R2 is a (2- 8C)alkylene group and R3 is an optionally substituted (1 -4C)alkyl group.

Suitably, Ri is H or (1 -2C)alkyl. In an embodiment, Ri is H or methyl. In a particular embodiment, Ri is H. In a further embodiment, Ri is methyl.

Suitably, R2 is a (2-4C)alkylene. In a particular embodiment, R2 is ethylene or propylene, particularly propylene.

Suitably, R3 is (1 -3C)alkyl and, more suitably, R3 is (1 -2C)alkyl. In an embodiment, R3 is methyl. In an embodiment, R3 is ethyl.

Suitable tri(alkoxy)silylalkylacrylates or tri(alkoxy)silylalkyl(meth)acrylates are known in the art. Particular examples include trimethoxysilylpropylacrylate, triethoxysilylpropylacrylate, trimethoxysilylpropyl(meth)acrylate and triethoxysilylpropyl(meth)acrylate.

In an embodiment, the co-polymer comprises one or more monomers bearing functional groups that are selected from a group of formula I as defined above, glycidyl (meth)acrylate, (meth)acryloyl chloride, maleic anhydride, hydroxyalkyl (meth)acrylates, (meth)acrylic acid, vinylbenzyl chloride, activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2- isocyonatoethyl (meth)acrylate, ethyleneglycol dicyclopentenyl ether methacrylate, 5- norbornene-2-methanol methacrylate, 2-(methacrylyoxy)ethyl acetoacetate and/or acetoxystyrene.

In an embodiment, the one or more monomers bearing functional groups (e.g. the crosslinking monomer of formula I) accounts for 10 to 100 mole % of the ethylenically monounsaturated monomer component of the copolymer. More typically, the one or more monomers bearing functional groups (e.g. the crosslinking monomer of formula I) accounts for 30 to 100 mole % of the ethylenically monounsaturated monomer component of the copolymer. In other embodiments of the invention, the one or more monomers bearing functional groups (e.g. the crosslinking monomer of formula I) accounts for 50 to 100 mole %, or 60 to 100 mole %, or 70 to 100 mole %, or 80 to 100 mole %, or 70 to 98 mole %, or 80 to 95 mole % of the ethylenically monounsaturated monomer component of the copolymer.

In an embodiment, the monounsaturated monomer component comprises the one or more monomers bearing functional groups (e.g. the crosslinking monomer of formula I) and an additional monounsaturated monomer. In such embodiments, the additional ethylenically monounsaturated monomers may account for 0 to 90 mole % of the ethylenically monounsaturated monomer component of the copolymer. More typically, the additional ethylenically monounsaturated monomers will account for 0 to 70 mole % of the ethylenically monounsaturated monomer component of the copolymer. In other embodiments of the invention, the additional ethylenically monounsaturated monomers may account for 0 to 50 mole %, or 0 to 40 mole %, or 0 to 30 mole %, or 0 to 20 mole %, or 2 to 30 mole %, or 5 to 20 mole % of the ethylenically monounsaturated monomer component of the copolymer.

The ethylenically polyunsaturated monomer

The ethylenically polyunsaturated (multifunctional) monomer (also referred to herein as "brancher(s)") may comprise a molecule containing at least two vinyl groups which may be polymerised via addition polymerisation. The monomers may be hydrophilic, hydrophobic, amphiphilic, neutral, cationic, zwitterionic, oligomeric or polymeric. Such monomers are often known as crosslinking agents in the art and may be prepared by reacting any di- or multifunctional monomer with a suitably reactive monomer. Examples include di- or multivinyl esters, di- or multivinyl amides, di- or multivinyl aryl compounds, di- or multivinyl alk/aryl ethers. Typically, in the case of oligomeric or polymeric di- or multifunctional branchers, a linking reaction is used to attach a polymerisable moiety to a di- or multifunctional oligomer or polymer. The brancher may itself have more than one branching point, such as T-shaped divinylic oligomers or polymers. In some cases, more than one ethylenically polyunsaturated (multifunctional) monomer may be used.

The corresponding allyl monomers to those listed above can also be used where appropriate.

Preferred multifunctional monomers include but are not limited to: divinyl aryl monomers such as divinyl benzene; (meth)acrylate diesters such as ethylene glycol di(meth)acrylate, propyleneglycol di(meth)acrylate and 1 ,3-butylenedi(meth)acrylate; poly(alkyleneglycol) di(meth)acrylates such as tetraethyleneglycol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and poly(propyleneglycol) di(meth)acrylate; divinyl (meth)acrylamides such as methylene bisacrylamide; butanediol di(meth)acrylate, hexanediol di(meth)acrylate, silicone-containing divinyl esters or amides such as (meth)acryloxypropyl-terminated poly(dimethylsiloxane); divinyl ethers such as poly(ethyleneglycol)divinyl ether; and tri-, tetra- or hexyl- (meth)acrylate esters such as trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerithritol hexa(meth)acrylate or glucose di- to penta(meth)acrylate. Further examples include vinyl or allyl esters, amides or ethers of pre-formed oligomers or polymers formed via ring-opening polymerisation such as oligo(caprolactam), oligo(caprolactone), poly(caprolactam) or poly(caprolactone), or oligomers or polymers formed via a living polymerisation technique such as oligo- or poly(1 ,4-butadiene).

Macrocrosslinkers or macrobranchers (multifunctional monomers having a molecular weight of at least 1 ,000 Daltons) are generally formed by linking a polymerisable moiety, such as a vinyl or aryl group, to a pre-formed multifunctional polymer via a suitable linking unit such as an ester, an amide or an ether. Examples of suitable polymers include di-functional poly(alkylene oxides) such as poly(ethyleneglycol) or poly(propyleneglycol), silicones such as poly(dimethylsiloxane)s, polymers formed by ring-opening polymerisation such as poly(caprolactone) or poly(caprolactam) or poly- functional polymers formed via living polymerisation such as poly(1 ,4-butadiene).

Preferred macrobranchers include poly(ethyleneglycol) di(meth)acrylate, poly(propyleneglycol) di(meth)acrylate, methacryloxypropyl-terminated poly(dimethylsiloxane), poly(caprolactone) di(meth)acrylate and poly(caprolactam) di(meth)acrylamide.

Branchers include methylene bisacrylamide, glycerol di(meth)acrylate, glucose di- and tri(meth)acrylate, oligo(caprolactam) and oligo(caprolactone). Multi end- functionalised hydrophilic polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group.

Further branchers include divinyl benzene, (meth)acrylate esters such as, for example, ethyleneglycol di(meth)acrylate, propyleneglycol di(meth)acrylate and 1 ,3- butylene di(meth)acrylate, oligo(ethylene glycol) di(meth)acrylates such as tetraethylene glycol di(meth)acrylate, tetra- or tri- (meth)acrylate esters such as pentaerthyritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylateand glucose penta(meth)acrylate. Multi end-functionalised hydrophobic polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group.

Multifunctional responsive polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group such as polypropylene oxide) di(meth)acrylate.

Preferred polyunsaturated monomers or branchers include: divinyl benzene, ethyleneglycol di(meth)acrylate, 1 ,4 butanediol di(methacrylate), hexane diol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and N, N'- methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and dipentaerithritol hexa(meth)acrylate.

The molar ratio of ethylenically polyunsaturated monomer component to the ethylenically monounsatu rated monomer component is suitably 1 :100 to 1 :4. More typically, the molar ratio of ethylenically polyunsaturated monomer component to the ethylenically monounsaturated monomer component is 1 :20 to 1 :4, or 1 :20 to 1 :5. The formation of the statistical branched amphiphilic copolymer

The statistical branched amphiphilic copolymer can be prepared by any suitable technique known in the art. For example, they may be prepared by the techniques described in WO2013/024307, the entire contents of which are incorporated herein by reference.

Suitably, the statistical branched amphiphilic copolymer can be prepared by an addition polymerisation process. Such a process typically comprises mixing together:

(a) one or more ethylenically monounsatu rated monomers;

(b) one or more ethylenically polyunsaturated monomers;

(c) a chain transfer agent; and

(d) an initiator; in a solvent and subsequently reacting said mixture to form a branched copolymer.

Suitably, from 1 to 25 mole % (based on the number of moles of monofunctional monomer(s)) the one or more polyunsaturated monomers is present.

Solvent

The reaction may be conducted in any suitable solvent for a polymerisation process. Examples of suitable solvents include alcohols (such as methanol, ethanol, propanol, etc.), tetrahydrofuran, aromatic compounds (such as benzene, toluene, xylene etc.). or Solveso esters (such as ethyl acetate, butyl acetate etc.), a carrier oil as defined hereinbefore, or, for hydrophilic polymers, water or an aquous solution could also be used.

Following the reaction, the copolymer product can be isolated from the solvent and then dispersed in a suitable carrier oil for the emulsification process of the invention.

Alternatively, in some embodiments, the reaction may be conducted in situ using an oil phase (e.g. a carrier oil) as the solvent. In a particular embodiment, the copolymer is synthesised directly within an oil phase (e.g. a carrier oil) which subsequently forms the oil phase in the emulsion. The chain transfer agent (CTA) and initiator

The chain transfer agent (CTA) is a molecule which is known to reduce molecular weight during a free-radical polymerisation via a chain transfer mechanism. These agents may be any thiol-containing molecule and can be either monofunctional or multifunctional. The agent may be hydrophilic, hydrophobic, amphiphilic, anionic, cationic, neutral, zwitterionic or responsive. The agent can also be an oligomer or a pre-formed polymer containing a thiol moiety. The agent may also be a hindered alcohol or similar free-radical stabiliser such as 2, 4-diphenyl-4-methyl-1 -pentene. Catalytic chain transfer agents, such as those based on transition metal complexes, e.g. cobalt bis(borondifluorodimethyl-glyoximate) (CoBF) may also be used. Suitable thiols include but are not limited to C2-C18 alkyl thiols such as dodecane thiol, thioglycolic acid, thioglycerol, cysteine and cysteamine. Thiol-containing oligomers or polymers may also be used, such as poly(cysteine) or an oligomer or polymer which has been post-functionalised to give a thiol group(s), such as poly(ethyleneglycol) (di)thio glycollate, or a pre-formed polymer functionalised with a thiol group, for example, reaction of an end or side-functionalised alcohol such as polypropylene glycol) with thiobutyrolactone, to give the corresponding thiol-functionalised chain- extended polymer. Multifunctional thiols may also be prepared by the reduction of a xanthate, dithioester or trithiocarbonate end-functionalised polymer prepared via a Reversible Addition Fragmentation Transfer (RAFT) or Macromolecular Design by the Interchange of Xanthates (MADIX) living radical method. Xanthates, dithioesters, and dithiocarbonates may also be used, such as cumyl phenyldithioacetate. Alternative chain transfer agents may be any species known to limit the molecular weight in a free-radical addition polymerisation including alkyl halides and transition metal salts or complexes. More than one chain transfer agent may be used in combination. When the chain transfer agent is providing the necessary hydrophilicity in the copolymer, it is preferred that the chain transfer agent is hydrophilic and has a molecular weight of at least 1 ,000 Daltons.

Where the polymer is comprised of primarily hydrophilic monomers and branchers it is preferred that the CTA is a hydrophobic compound. Hydrophobic CTAs include but are not limited to linear and branched alkyl and aryl (di)thiols such as dodecanethiol, octadecyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3- mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9- nonanedithiol and 2,4-diphenyl-4-methyl-1 -pentene. Hydrophobic macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from hydrophobic polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed hydrophobic polymer can be post functionalised with a compound such as thiobutyrolactone.

Hydrophilic CTAs typically contain hydrogen bonding and/or permanent or transient charges. Hydrophilic CTAs include but are not limited to thio-acids such as thioglycolic acid and cysteine, thioamines such as cysteamine and thio-alcohols such as 2-mercaptoethanol, 3-mercaptopropanoic acid, thioglycerol and ethylene glycol mono- (and di-)thio glycollate. Hydrophilic macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from hydrophilic polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed hydrophilic polymer can be post functionalised with a compound such as thiobutyrolactone.

Responsive macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from responsive polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed responsive polymer, such as polypropylene glycol), can be post functionalised with a compound such as thiobutyrolactone.

The residue of the chain transfer agent may comprise 0 to 80 mole %, preferably 0 to 50 mole %, more preferably 0 to 40 mole % and especially 0.05 to 30 mole %, of the copolymer (based on the number of moles of monounsaturated monomer).

The initiator is a free-radical initiator and can be any molecule known to initiate free- radical polymerisation such as azo-containing molecules, persulfates, redox initiators, peroxides, phenyl benzyl ketones. These may be activated via thermal, photolytic or chemical means. Examples of these include but are not limited to azo- compounds e.g. 2,2'-azobisisobutyronitrile (AIBN), azobis(4-cyanovaleric acid) or peroxides such as benzoyl peroxide, and the Luperox® range from Arkema such as di-t-butyl peroxide (Luperox® Dl), t-butyl peroxybenzoate, (Luperox® P), dicumylperoxide (Luperox® DCP), di-t-amyl peroxide (Luperox® DTA), 1 - hydroxycyclohexyl phenyl ketone, hydrogenperoxide/ascorbic acid. Iniferters such as benzyl-N,N-diethyldithiocarbamate can also be used. In some cases, more than one initiator may be used. The initiator may be a macroinitiator having a molecular weight of at least 1 ,000 Daltons. In this case, the macroinitiator may be hydrophilic, hydrophobic, or responsive.

Preferably, the residue of the initiator in a free-radical polymerisation comprises 0 to 40% w/w, preferably 0.01 to 30% w/w and especially 0.01 to 20% w/w, of the copolymer based on the total weight of the monomers.

The use of a chain transfer agent and an initiator is preferred. However, some molecules can perform both functions.

Hydrophilic macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from hydrophilic polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use in Atom Transfer Radical Polymerisation (ATRP) with a suitable low valency transition metal catalyst, such as CuBr Bipyridyl.

Hydrophobic macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from hydrophobic polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use with ATRP.

Responsive macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from responsive polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use with ATRP.

Preferred chain transfer agents include: dodecanethiol, octadecyl mercaptan, 2- ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3-mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9-nonanedithiol and 2,4-diphenyl-4- methyl-1 -pentene.

Preferred initiators include: 2,2'-azobisisobutyronitrile (AIBN), azobis(4-cyanovaleric acid), and compounds from the Luperox® range from Arkema such as benzoyl peroxide, di-t-butyl peroxide (Luperox® Dl), t-butyl peroxybenzoate, (Luperox® P), dicumylperoxide (Luperox® DCP), di-t-amyl peroxide (Luperox® DTA), 1 - hydroxycyclohexyl phenyl ketone and hydrogenperoxide/ascorbic acid.

Reaction conditions for the addition polymerisation

The addition polymerisation suitably process proceeds via a solution polymerisation wherein the reactants, monomer(s), brancher(s), chain transfer agent(s) and initiator(s), are added to a solvent (e.g. methanol, ethanol or a carrier oil) and polymerisation proceeds through initiation. It is preferred that the reactants are soluble in the solvent (e.g. methanol, ethanol or a carrier oil) at the reaction temperature although they can also be dispersed in the solvent, likewise it is preferred that the addition copolymer product is also soluble in the solvent at the reaction temperature although the addition copolymer product can also be dispersed within the solvent following polymerisation. The solids content of the polymerisation process can be from 0.5 % to 90 % w/w, preferably between 5 % and 80 % w/w and especially between 10 and 70 % w/w.

The polymerisation can proceed via a batch process wherein all of the components are added to the reaction vessel at the start of the polymerisation process and the addition copolymer product isolated in the solvent (e.g. methanol, ethanol or a carrier oil) following reaction. The polymerisation can also take place via a feed process whereby the reactants are added continuously throughout the polymerisation process from one or more separate source vessels, this can be done in such a way that the monomers are consumed uniformly during the polymerisation process to avoid monomer build-up, so-called accumulation. Additionally it is preferred in this case that the initiator is added separately in order to cease the reaction by stopping the initiator feed, if required, this process is known in the art as a starved-feed polymerisation and is common in solution or emulsion polymerisation processes. In this case the reactants can be added neat to the solvent or more preferably added as solutions or dispersions within the solvent.

This process can also be performed where a portion of the reaction solution is added to the vessel at the start of the process, typically around 20 to 30 % and the remaining constituents are added throughout the process, so-called semi-batch process. Following the addition of the reactants the polymerisation can be allowed to proceed for a period of time, in some instances an additional aliquot of initiator can be added to consume any free monomer that may be present.

The initiation of the polymerisation can occur through thermal means or via electromagnetic radiation such as ultra violet light or gamma rays, such as from a Co-60 source, or through chemical means such as a REDOX reaction with an oxidant or reducing agent and an appropriate initiator. The reaction can also proceed in a flow or tubular reactor where the reactants are passed through a tubular vessel with a designated polymerisation zone, usually a heated section with a temperature gradient, and the reactants are obtained after a set residence time. In this process the polymerisation solution can also be re-circulated until the appropriate degree of polymerisation is obtained.

In a batch, fed or semi-batch process the reaction vessel can be glass, mild steel, stainless steel, glass-lined or Hastelloy in construction and fitted with appropriate heating sources such as an oil or steam-heated jacket and cooling such as a condenser or cooling coils externally or internally fitted on or in the vessel. Where necessary the reactants can be dosed into the vessel manually or via gravity or metered pumps. It is preferred that the reaction proceeds at atmospheric pressure although higher pressures can be used with lower boiling point reactants or carrier oils.

It is preferred that the polymerisation reaction occurs at a temperature of 60 to 180 °C. The reaction time can be between 3 hours to 48 hours, preferably 5 to 24 hours.

The process described above provides the copolymer in a solvent. If the solvent is not a carrier oil, then the polymer can be isolated from the reaction solvent, optionally purified using conventional techniques known in the art and dispersed within a carrier oil phase for the subsequent emulsification process of the invention.

In embodiment where the solvent used for the polymerisation reaction is a carrier oil, then the resultant carrier oil / copolymer composition can then be used directly in the emulsification process, as defined further herein. The first polymensable species

The first polymensable species is any oil soluble or dispersible reactant that is capable of undergoing an interfacial polymerisation reaction with a water soluble second polymensable species at an oil-water interface. A person skilled in the art will therefore be able to select suitable reactants to use. Particular examples of suitable materials include: di- or poly-isocanates, di- or poly- benzyl species, di- or poly-acids or acid chlorides.

The second polymensable species

The second polymensable species is any water soluble or dispersible reactant that is capable of undergoing an interfacial polymerisation reaction with an oil soluble first polymerisable species at an oil-water interface.

A person skilled in the art will therefore be able to select suitable reactants to use. Particular examples of suitable materials include: di- or poly-alcohols or di- or poly- amines.

Emulsion formation

The oil phase and the aqueous phase may be emulsified by any suitable emulsification technique known in the art. For example, the emulsion may be prepared using any common equipment known in the art for this purpose, such as, for example, high shear mixers, homogenisers, ultrasound, membrane emulsification, or microfluidics. A person skilled in the art will understand how to vary the properties of the emulsion by varying equipment used, the shear forces applied, the agitation time etc. to provide an emulsion having the desired properties. A person skilled in the art will also be able to vary the amount of the copolymer defined herein in order to provide the desired level of stabilisation to the emulsion droplets.

Additional emulsifiers may also be used in the emulsification processes described herein. For example, the amphiphilic addition copolymers can also be used in combination with non-functional small molecule or polymeric emulsifiers. In such cases, an emulsion prepared in accordance with the present invention may comprise the cross-linkable copolymer emulsifiers together with a non-reactive emulsifier. Capsule formation occurs via the cross-linking of the copolymers. This is of particular advantage where further functionality needs to be introduced in a capsule via the use of, for example, a further emulsifier. Additionally, the cost of preparing the capsules can be reduced by the use of commodity surfactants or emulsifiers with only minimal changes to existing formulation procedures being required.

Polymeric capsule formation

The polymeric capsule is formed by the interfacial polymerisation reaction between the first polymerisable species in the oil phase and a second polymerisable species in the aqueous phase. Any suitable catalysts required to promote this reaction may be added to either during or after the emulsification process.

In addition, in embodiments where the statistical branched copolymer comprises one or more functional groups capable of reaction with one another or reaction with a separate crosslinking agent, the crosslinking of the copolymer emulsifier further contributes to the formation of the polymeric capsule around the dispersed phase. It is generally preferred that encapsulation proceeds through use of a functionalised copolymeric emulsifier and the interfacial reaction between the first and second polymerisable species.

Without wishing to be bound by any particular theory, the polymeric emulsifier is thought to act as a scaffold maintaining the size and structure of the growing encapsulate. Where suitable functional groups are present within the copolymer emulsifier, it can react with the shell-forming reagents and become covalently attached, and as such, part of the encapsulate shell wall. In addition, the reaction preferably occurs via an intermolecular 'self-cross-linking' reaction between addition copolymers and the additional cross-linking mechanisms at the same oil/water interface.

The capsules formed can be further post-modified with reagents to provide, for example, increased stability or surface recognition. Reactive links can be introduced into the cross-linked structure in order to facilitate rupturing of the capsules upon demand, for example via a change in temperature or pH. Similarly, the capsules can be cross-linked together to give higher order structures such as "beads" or monoliths where the emulsion droplets have been aggregated prior to the final cross-linking step. Once formed, the contents of the capsules can also be removed by a washing material to obtain hollow receptacles suitable for filling with other benefit agent materials, or for use in their own right in for example composites where they could be utilised as an additive to alter the opacity, dielectric constant or strength of a composite, coating or film.

The branched addition copolymers of the current invention tend to stabilise the emulsions prior to capsule formation to a better degree than chemically analogous linear copolymers, by virtue of their higher molecular weight and increased end- groups and branched architecture. This can therefore lead to better capsule formation in the interfacial polymerisation/crosslinking step as it reduces the requirement to complete the interfacial polymerisation/crosslinking within a short time period, that is the polymeric capsules do not need to form immediately as in the case for the linear copolymer encapsulating agents.

The polymer capsule formation reactions must be able to proceed at the oil/water interface of the emulsion. Suitably, the reactions proceed under mild conditions and may optionally be catalysed (for example by the addition of an acid or base).

In an embodiment of the invention where the copolymer comprises one or more functional alkoxysilane functional groups, for example by the presence of one or monomers of formula I defined hereinbefore, the cross-linker suitably comprises an alkoxysilane group that is capable of reacting with the alkoxysilane groups present copolymer. This is commonly known as a sol-gel process. This sol-gel reaction can proceed at the oil-water interface and is driven by the hydrolysis of the alkoxysilane functional groups. This process can occur by simply leaving the emulsion to stand for a period of time (typically 2 to 24 hours) or it may be catalysed by the addition of an acid or base. Thus, the formation of these crosslinks within the copolymer may be facilitated by allowing the emulsion to stand for a period of time, optionally at neutral pH. However, the reaction can be catalysed by the addition of either an acid or a base such as sulfuric, hydrochloric, phosphoric acid or a compound which hydrolyses itself to give an acidic moiety such as δ-gluconolactone or an alkali hydroxide, carbonate or bicarbonate such as sodium hydroxide, sodium carbonate or sodium bicarbonate at pH ranges from 2 to 13. Preferably the emulsion is crosslinked through a change in pH and via a sol-gel reaction of the trialkoxysilyl moieties present in the copolymer. The particle size of the polymer capsules can be controlled at least in part by controlling the size of the emulsion. This can be achieved by techniques known in the art such as varying the production parameters (e.g. agitation speeds, times, temperatures) and the composition of the emulsion (the amount of emulsifier, the nature of the different phases etc.). Preferably the average size of the capsules is smaller than 100 μιη, more preferably smaller than 50 μιη. Preferably the polymer capsule has an internal oil phase and is formed in an aqueous bulk phase.

In a preferred embodiment the capsule comprises a benefit agent, wherein the benefit agent is incorporated in the dispersed phase.

In an embodiment, the carrier oil is the dispersed phase and crosslinking of the copolymers forms polymeric capsules encapsulating the dispersed phase.

The polymeric capsule may be configured to release the encapsulated benefit agent in a controlled manner over a period of time or, alternatively, it might be configured to release the encapsulated benefit agent in a more immediate (e.g. a "burst" or "rupture" release profile) manner.

The invention also provides a method of preparing a capsule, comprising a step wherein the copolymer/carrier oil composition incorporating a benefit agent or agent(s) is mixed with a hydrophobic liquid under conditions whereby at least one of the monounsaturated monomer(s) and polyunsaturated monomer(s) and chain transfer agent do not form a non-covalent bond with any other of the monounsaturated monomer(s) and polyunsaturated monomer(s) and chain transfer agent. Under these conditions the polymer is in a non-interacting form. The capsule can be then used to protect or isolate the active agent from the final formulation or to deliver the benefit agent to the desired locus of action by, for example, a "rupture" or "burst release" mechanism.

The polymeric capsules formed can be further post-modified with reagents to provide, for example, increased stability or surface recognition. Reactive links can be introduced into the crosslinked structure in order to facilitate rupturing of the capsules in response to certain environmental conditions, for example via a change in temperature, ionic strength or pH. Similarly, the capsules can be crosslinked together to give higher order structures such as "beads" or monoliths where the emulsion droplets have been aggregated prior to the final crosslinking step. Once formed, the contents of the capsules can also be removed by a washing material to obtain hollow receptacles suitable for filling with other benefit agent materials, or for use in their own right in for example composites where they could be utilised as an additive to alter the opacity, dielectric constant or strength of a composite, coating or film.

In embodiments where the branched addition copolymers have associating functionality, such as H-bonding groups, they may aggregate in solution upon the application of an external trigger such as in the case of capsules decorated with carboxylic acid functionality. In this case, the formed capsules may assemble via hydrogen-bonding (with inherent changes in hydrophobicity) when below the pKa of the acid group and reversibly disassemble upon the application of an increase in pH.

The encapsulation of hydrophobic benefit agents in particular is of industrial relevance where a hydrophobic component is required to be delivered from, formulated in, or isolated from, an aqueous environment. For example the polymeric capsule may protect a benefit agent compound from a hydrophilic formulation where the bulk aqueous environment can lead to degradation of the hydrophobic material or is, for example, rich in additional surfactants which can affect the performance of the hydrophobic benefit agent. The capsule may also be post-modified in order to improve the selectivity of the capsule, such as the covalent attachment of surface- substantive or bio-active materials, for example in the specific delivery of pharmaceutical agents. The capsules may also be designed to assemble and disassemble upon changes in the aqueous environment, such as pH, this is particularly desirable in the preparation of a "capsule concentrate" in the associated form for transportation purposes and formulation dilution at the required destination, that is On-site'. The payload of the capsule can also be washed-out to yield hollow spheroids which can be filled or used in their own right as, for example, in composite materials. Examples include but are not limited to: the encapsulation of bioactive compounds such as pharmaceuticals or agrochemicals; nutritional agents such as vitamins; cosmetics, catalysts, dyes, pigments, flavours, fragrances, lubricating oils, emollients, natural oils and waxes, paints, inks, coatings, sealants and tissue engineering scaffolds. Crosslinking agent

In some embodiments, a crosslinking agent may be added to the emulsion. The crosslinking agent is an agent capable of forming a covalent bond with the statistical amphiphilic branched copolymer of the invention. The crosslinker molecule reacts with the amphiphilic branched copolymer of the invention at the boundary of the dispersed phase within the continuous phase, typically at the oil-water interface for oil-in-water encapsulates, and can be introduced to the emulsion mixture by dissolution in the dispersed phase, typically hydrophobic in nature, or the continuous phase, typically hydrophilic and especially aqueous in nature. The crosslinking agent can also be added to the system following emulsification, such as, for example, by dissolving in the continuous phase.

It is a requirement that the crosslinking agent is at least di-functional in order to attain crosslinked structures with the amphiphilic branched copolymer. The crosslinking reaction may also provide additional benefits to the capsule wall such as an increase in wall thickness, rigidity, reduction in porosity, introduction or changes in wall surface charge or provide a means to introduce a surface substantive moiety or a weak link in the capsulate surface. The crosslinking agent can react with the amphiphilic branched copolymer via a number of conventional chemical transformations such as nucleophilic substitution, electrophilic addition, ring-opening reactions, sol-gel reactions (such as the reaction with di-tri-or poly alkoxy silanes), Diels-Alder reactions, ester formation, amide formation, urethane formation, urea formation, carbonate formation, thiol-ene formation, addition polymerisation (from the polymerisation of unreacted or pendant groups on the amphiphilic branched copolymer with an additional monomer or di-or poly-functional monomer) and the 1 + 3 Huisgen cycloaddition reaction, so-called "click chemistry".

In particular the reaction with a di-or trifunctional alkoxysilanes are preferred and can react with pendant alkoxysilyl units which may be incorporated in the amphiphilic branched copolymer and suitable additional crosslinking agents include tri and tetra alkoxysilanes such as tetramethyl orthosilicate and tetraethyl orthosilicate, sodium silicate, bis(triethoxysilyl)ethane, bis(trimethoxyethyl)silane, tris-[3- (trimethoxysilyl)propyl]isocyanurate, tris-[3-(triethoxysilyl)propyl]isocyanurate, mercapropropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-octanoylthio-1 - propyl triethoxysilane, aminopropyl trialkoxysilanes such as aminopropyltrimethoxy silane or aminopropyl triethoxysilane, aminopropyl methyl diethoxysilane, Ν-(β- aminoethyl)-Y-aminopropyl trimethoxysilane, N-[N'-(2-aminoethyl)aminoethyl]-3- aminopropyl trimethoxysilane, N-phenyl aminopropyl trimethoxysilane, N-ethyl- aminoisobutyl trimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, ureidopropyl trimethoxysilane, isocyanatopropyl triethoxysilane, isocyanatopropyl trimethoxysilane, glycidoxypropyl trimethoxysilane, glycidoxypropyl triethoxysilane, 3,4 - epoxycyclohexyl - ethyl trimethoxysilane and 3,4 - epoxycyclohexyl - ethyl triethoxysilane.

The crosslinking agent may be present at an amount of 0.1 to 40 % by weight of the amphiphilic branched copolymer. In an embodiment, the cross-linking agent is present at an amount of 0.5 to 30 % by weight of the amphiphilic branched copolymer. In a further embodiment, the cross-linking agent is present at an amount of 1 to 20 % by weight of the amphiphilic branched copolymer.

In certain embodiments, the additional crosslinker is present at stoichiometric amount relative to the functionalisation present on the amphiphilic copolymer. In other embodiments, the functionality present on the polymer may in excess relative to the cross-linking agent. The use of stiochiometirc amounts or situations where the functionality present on the polymer is in an excess may occur, for example, in the case of the reaction of a benzyl halide residue on the amphiphilic branched copolymer, such as that derived from the incorporation of a monomer of vinyl benzyl chloride, and a diamine, such as hexamethylene diamine.

In other embodiments, the additional crosslinker can be present at an amount of 0.1 to 10 times excess by weight. This may be the case, for example, where additional crosslinker can co-polymerise with a functional group in the polymer by a sol-gel chemical reaction, as described previously herein.

The present invention also provides a polymer capsule obtainable by, obtained by, directly obtained by, or formed by, a process as defined in the eighth aspect of the invention.

Particular embodiments

The following numbered paragraphs 1 ) to 53) are not claims, but instead describe particular embodiments of aspects 8 to 9 of the invention: 1 ) A method of preparing a polymeric capsule, the process comprising: providing a mixture comprising an oil phase, an aqueous phase, a statistical branched amphiphilic copolymer emulsifier, a first polymerisable species present in the oil phase, a second polymerisable species present in the aqueous phase, wherein said first and second polymerisable species can react with one another to form a polymer; emulsifying the mixture to form an emulsion having a dispersed phase and a continuous phase; forming a polymeric capsule by the reaction between the first and second polymerisable species at the oil/water interface.

2) A method according to numbered paragraph 1 , wherein the emulsion is an oil- in-water emulsion.

3) A method according to numbered paragraph 1 , wherein the emulsion is a water-in-oil emulsion.

4) A method according to any one of the preceding numbered paragraphs, wherein the statistical branched amphiphilic copolymer comprises at least two polymeric chains which are covalently linked by a bridge; and wherein the at least two chains are formed by the polymerisation of one or more ethylenically monounsaturated monomers and the bridge is formed by the polymerisation of at least one ethylenically polyunsaturated monomer; and wherein the copolymer optionally comprises one or more functional groups capable of reacting with functional groups present on the crosslinking agent.

5) A method according to numbered paragraph 4, wherein the statistical branched amphiphilic copolymer comprises at least two polymeric chains which are covalently linked by a bridge other than at their ends.

6) A method according to any one of numbered paragraphs 4 to 5, wherein the statistical branched amphiphilic copolymer comprises the residue of a chain transfer agent and/or an initiator; and at least one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophilic residue, and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophobic residue.

7) A method according to any one of numbered paragraphs 4 to 6, wherein the molar ratio of polyunsaturated monomer(s) to monounsaturated monomer(s) in the statistical branched amphiphilic copolymer is from 1 :100 to 1 :4.

8) A method according to any one of numbered paragraphs 4 to 7, wherein the molar ratio of the ethylenically polyunsaturated monomer component to the ethylenically monounsaturated monomer component of the copolymer is 1 :50 to 1 :4.

9) A method according to any one of numbered paragraphs 4 to 7, wherein the molar ratio of the ethylenically polyunsaturated monomer component to the ethylenically monounsaturated monomer component of the copolymer is 1 :20 to 1 :4.

10) A method according to any one of numbered paragraphs 4 to 9, wherein the copolymer is formed by an addition polymerisation process, which comprises mixing together:

(a) the one or more ethylenically monounsaturated monomers;

(b) the one or more ethylenically polyunsaturated monomers;

(c) a chain transfer agent; and

(d) an initiator; in a solvent and reacting the mixture to form the statistical branched amphiphilic copolymer

1 1 ) A method according to numbered paragraph 10, wherein from the amount of polyunsaturated monomer is 1 to 25 mole% (based on the number of moles of monounsaturated monomer(s)).

12) A method according to any one of numbered paragraphs 4 to 1 1 , wherein the statistical branched amphiphilic copolymer comprises a functional group capable of reacting with a functional group present on the crosslinking agent by a reaction selected from the group consisting of nucleophilic substitution, electrophilic addition, ring-opening reactions, sol-gel reactions (such as the reaction between di-tri-or poly alkoxy silanes), Diels-Alder reactions, ester formation, amide formation, urethane formation, urea formation, carbonate formation, thiol-ene formation, addition polymerisation, and the 1 + 3 Huisgen cycloaddition reaction (so-called "click chemistry").

13) A method according to any one of numbered paragraphs 4 to 12, wherein the statistical branched amphiphilic copolymer comprises one or more functional groups selected from the group consisting of amines, alcohols, thiols, ketones, carboxylic acids, acid chlorides, halogens, alkoxysilanes, epoxides, and acetoacetates.

14) A method according to any one of numbered paragraphs 4 to 12, wherein the statistical branched amphiphilic copolymer comprises one or more pendant alkoxysilane functional groups.

15) A method according to numbered paragraph 14, wherein the pendent alkoxysilane groups are pendant mono-, di- or tri-(1 -2C)alkoxysilane functional groups.

16) A method according to numbered paragraph 14 or 15, wherein the alkoxysilane groups are present on an ethylenically monounsatu rated monomer component.

17) A method according to numbered paragraph 16, wherein the polymer comprises one or more ethylenically monounsatu rated monomers selected from: a monomer of Formula (1 ):

H ₂ C=CH(Ri)-C(O)-O-R2-Si(OR3)3

Formula (1 ) wherein Ri is H or an optionally substituted (1 -4C)alkyl group; R2 is a (2- 8C)alkylene group and R3 is an optionally substituted (1 -4C)alkyl group; glycidyl (meth)acrylate, (meth)acryloyl chloride, maleic anhydride, hydroxyalkyl (meth)acrylates, (meth)acrylic acid, vinylbenzyl chloride, activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2-isocyonatoethyl (meth)acrylate, ethyleneglycol dicyclopentenyl ether methacrylate, 5-norbornene-2-methanol methacrylate, 2-(methacrylyoxy)ethyl acetoacetate and/or acetoxystyrene. 18) A method according to numbered paragraph 17, wherein in the ethylenically monounsaturated crosslinking monomer of formula I, Ri is H or (1 -2C)alkyl; Fte is a (2-4C)alkylene; and Ra is (1 -3C)alkyl.

19) A method according to any one of numbered paragraphs 17 or 18, wherein in the ethylenically monounsaturated crosslinking monomer of formula I, Ri is H or methyl; R2 is ethylene or propylene; and R3 is (1 -2C)alkyl.

20) A method according any one of numbered paragraphs 17 to 19, wherein the crosslinking monomer of formula I is selected from trimethoxysilylpropylacrylate, triethoxysilylpropylacrylate, trimethoxysilylpropylmethacrylate and

triethoxysilylpropylmethacrylate.

21 ) A method according to any one of numbered paragraphs 17 to 20, wherein the one or more monounsaturated monomers accounts for 10 to 100 mole% of the ethylenically monounsaturated monomer component of the copolymer.

22) A method according to numbered paragraph 21 , wherein the one or more monounsaturated monomers accounts for 60 to 100 mole% of the ethylenically monounsaturated monomer component of the copolymer.

23) A method according to any one of numbered paragraphs 17 to 22, wherein the polymer further comprises one or more additional ethylenically monounsaturated monomers.

24) A method according to numbered paragraph 23, wherein the one or more additional ethylenically monounsaturated monomers account for 0 to 90 mole% of the ethylenically monounsaturated monomer component of the copolymer.

25) A method according to numbered paragraph 24, wherein the one or more additional ethylenically monounsaturated monomers account for 0 to 40 mole% of the ethylenically monounsaturated monomer component of the copolymer.

26) A method according to any one of numbered paragraphs 4 to 25, wherein the ethylenically polyunsaturated monomer is selected from the group consisting of divinyl benzene, ethyleneglycol di(meth)acrylate, 1 ,4 butanediol di(methacrylate), hexane diol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and N, N'- methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and dipentaerithritol hexa(meth)acrylate.

27) A method according to any one of numbered paragraphs 6 to 26, wherein the chain transfer agent (CTA) is a hydrophobic compound.

28) A method according to numbered paragraph 27, wherein the hydrophobic CTA is selected from linear and branched alkyl and aryl (di)thiols (e.g. dodecanethiol, octadecyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3- mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9- nonanedithiol and 2,4-diphenyl-4-methyl-1 -pentene).

29) A method according to any one of numbered paragraphs 6 to 26, wherein the chain transfer agent (CTA) is a hydrophilic compound.

30) A method according to numbered paragraph 29, wherein the hydrophilic CTA is selected from thio-acids (e.g. thioglycolic acid and cysteine), thioamines (e.g. cysteamine) and thio-alcohols (e.g. 2-mercaptoethanol, 3-mercaptopropanoic acid, thioglycerol and ethylene glycol mono- (and di-)thio glycollate).

31 ) A method according to any one of numbered paragraphs 6 to 30, wherein the chain transfer agent (CTA) is present at 0 to 80 mole % (based on the number of moles of monounsaturated monomer).

32) A method according to numbered paragraph 31 , wherein the chain transfer agent (CTA) is present at 0 to 50 mole % (based on the number of moles of monounsaturated monomer).

33) A method according to any one of numbered paragraphs 10 to 32, wherein the initiator is a free-radical initiator.

34) A method according to any one of numbered paragraphs 10 to 33, wherein the initiator is present in an amount of 0.01 to 40% w/w.

35) A method according to any one of numbered paragraphs 10 to 34, wherein the solvent is a carrier oil.

36) A method according to any one of the preceding numbered paragraphs, wherein oil phase is a carrier oil and the concentration of the statistical branched amphiphilic copolymer in the carrier oil is 0.5 % to 90 % w/w. 37) A method according to any one of the preceding numbered paragraphs, wherein the carrier oil has a boiling point above 80 °C.

38) A method according to any one of the preceding numbered paragraphs, wherein the carrier oil is selected from the group consisting of mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecan, docosane, hexadecane, ketones such as cyclohexanone, poly(dimethyl siloxanes), diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, ethylhexyl palmitate (octyl palmitate), palmitate, myristyl myristate, stearyl stearate, diisopropyl adipate, and caprylic/capric triglyceride. Corn oil, castor oil, coconut oil, cottonseed oil, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, pine oil, sesame oil, sunflower seed oil, safflower oil and medium chain triglycerides.

39) A method according to any one of the preceding numbered paragraphs, wherein the oil phase or the aqueous phase is, or comprises, a benefit agent.

40) A method according to numbered paragraph 39, wherein the emulsion is an oil- in-water emulsion and the oil phase comprises a benefit agent.

41 ) A method according to any one of the preceding numbered paragraphs wherein the first polymerisable species is selected from the group consisiting of di- or poly- isocanates, di- or poly-benzyl species, di- or poly-acids or acid chlorides.

42) A method according to any one of the preceding numbered paragraphs wherein the second polymerisable species is selected from the groups consisting of: di- or poly-alcohols or di- or poly-amines

43) A method according to any one of the preceding numbered paragraphs, wherein a crosslinking agent that comprises two or more functional groups capable of reacting with functional groups present on the copolymer to crosslink adjacent copolymer molecule together is added prior to, during or after the emsulification step.

44) A method according to numbered paragraph 43, wherein the crosslinking agent reacts with the copolymer by a reaction selected from the group consisting of nucleophilic substitution, electrophilic addition, ring-opening reactions, sol-gel reactions (such as the reaction between di-tri-or poly alkoxy silanes), Diels-Alder reactions, ester formation, amide formation, urethane formation, urea formation, carbonate formation, thiol-ene formation, addition polymerisation, and the 1 + 3 Huisgen cycloaddition reaction (so-called "click chemistry").

45) A method according to any one of numbered paragraphs 43 to 44, wherein crosslinking agent comprises one or more alkoxy silanes moieties.

46) A method according to any one of numbered paragraphs 43 to 45, wherein crosslinking agent is selected from tetramethyl orthosilicate and tetraethyl orthosilicate, sodium silicate, bis(triethoxysilyl)ethane, bis(trimethoxyethyl)silane, tris- [3-(trimethoxysilyl)propyl]isocyanurate, tris-[3-(triethoxysilyl)propyl]isocyanurate, mercapropropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-octanoylthio-1 - propyl triethoxysilane, aminopropyl trialkoxysilanes such as aminopropyltrimethoxy silane or aminopropyl triethoxysilane, aminopropyl methyl diethoxysilane, Ν-(β- aminoethyl)-Y-aminopropyl trimethoxysilane, N-[N'-(2-aminoethyl)aminoethyl]-3- aminopropyl trimethoxysilane, N-phenyl aminopropyl trimethoxysilane, N-ethyl- aminoisobutyl trimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, ureidopropyl trimethoxysilane, isocyanatopropyl triethoxysilane, isocyanatopropyl trimethoxysilane, glycidoxypropyl trimethoxysilane, glycidoxypropyl triethoxysilane, 3,4 - epoxycyclohexyl - ethyl trimethoxysilane and 3,4 - epoxycyclohexyl - ethyl triethoxysilane.

47) A method according to any one of the preceding numbered paragraphs, wherein the step of forming a polymeric capsule by the reaction between the first and second polymerisable species at the oil/water interface involves allowing the emulsion to stand for a period of 0.5 to 48 hours.

48) A method according to any one of the preceding numbered paragraphs, wherein the statistical branched copolymer comprises one or more functional groups capable of reaction with one another or reaction with a separate crosslinking agent, and the crosslinking of the copolymer emulsifier further contributes to the formation of the polymeric capsule around the dispersed phase of the emulsion.

49) A method according to numbered paragraph 48, wherein the copolymer and any crosslinking agent present comprise functional alkoxysilane groups and the step of forming the polymeric shell further comprises allowing the copolymer molecules to crosslink with one another and/or any crosslinking agent present to form an additional covalently linked polymeric capsule shell at the interface between the oil phase and the aqueous phase. 50) A method according to numbered paragraph 49, wherein the emulsion to stand for a period of 0.5 to 48 hours and an acid or base is optionally added to catalyse the reaction.

51 ) A polymer capsule obtainable by a process as defined in any one of numbered paragraphs 1 to 45.

52) A polymer capsule according to numbered paragraph 51 , wherein the particle size of the capsule is less than 100 microns.

53) A polymer capsule according the numbered paragraph 51 or 52, wherein the capsule comprises a benefit agent.

ASPECTS 10 AND 1 1 OF THE INVENTION Preparation of polymeric capsules

The present invention provides a method of preparing a crosslinked polymeric capsule, the process comprising: providing a mixture comprising an oil phase, an aqueous phase, a statistical branched amphiphilic copolymer bearing one or more functional groups and a crosslinking agent bearing two or more functional groups capable of reacting with the functional groups present on the statistical branched amphiphilic copolymer to form crosslinks between adjacent copolymer molecules; emulsifying the mixture to form an emulsion; allowing the crosslinking agent to react with the functional groups on the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the oil phase and the aqueous phase; wherein the statistical branched amphiphilic copolymer comprises at least two polymeric chains which are covalently linked by a bridge; and wherein the at least two chains are formed by the polymerisation of one or more ethylenically monounsaturated monomers and the bridge is formed by the polymerisation of at least one ethylenically polyunsaturated monomer; and wherein the copolymer comprises one or more functional groups capable of reacting with functional groups present on the crosslinking agent. The oil phase

Any suitable oil phase can be used in the process of the present invention. The oil phase is suitably a carrier oil as defined hereinbefore.

Suitably, the oil phase comprises the statistical branched amphiphilic copolymer defined hereinbefore. Typically, the copolymer will be present in an amount of between 0.5 to 90 % w/w preferably 5 to 80 % w/w and especially 10 to 70 % w/w in the carrier oil.

Typically, the emulsion will be an oil-in-water emulsion. In such cases, and in addition to the copolymers of the present invention, the carrier oil may further comprise one or more benefit agents either dissolved or dispersed within the carrier oil. In an alternative embodiment, the carrier oil itself is a benefit agent.

The oil phase may further comprise the crosslinking agent at an amount of 0.1 to 40 % by weight of the amphiphilic branched copolymer. In an embodiment, the cross- linking agent is present at an amount of 0.5 to 30 % by weight of the amphiphilic branched copolymer. In a further embodiment, the cross-linking agent is present at an amount of 1 to 20 % by weight of the amphiphilic branched copolymer.

The aqueous phase

Any suitable aqueous medium may be used as the aqueous phase in the emulsion process.

Typically, the aqueous phase will be the continuous phase, but in certain embodiments of the invention, the emulsion may be a water-in-oil emulsion and the aqueous phase will be the dispersed phase. In embodiments where the aqueous phase is the dispersed phase, the aqueous phase may be, or may further comprise, a benefit agent.

Benefit agents

Any suitable benefit agent may be used in the process of the present invention. For example, the benefit agent may include fragrances, UV absorbers, emollient oils, insecticides, phase change materials, dyes, pigments, detergents, printing inks, perfumes, silicone conditioners, shampoos, biocides, adhesives, corrosion inhibitors, anti-fouling agents, flavours, cosmetic actives, oxidizing agents, personal care actives, medicines, agrochemicals, fertilizers, fats, oils, nutrients, enzymes, liquid crystals, paints, rustproofing agents, recording materials, catalysts, chemical reactants and magnetic substances or combination thereof can be used directly or dissolved or dispersed in the oily substance as used herein depending on the purpose of use.

Fragrances include, for example, compounds which impart or mask odours for homecare, personal care and industrial uses such as alcohols, esters, terpenes, terpenoids, aromatic compounds, thiols and amines from natural or synthetic sources and include linalool, coumarin, geraniol, citral, limonene, citronellol, eugenol, cinnamal, cinnamyl alcohol, benzyl salicylate, menthol, menthyl lactate, eucalyptol, thymol, methyl salicylate, methylfuran, menthone, cinnamaldehyde. Typical representative examples of essential oils include, but are not limited to oils of orange, lavender, peppermint, lemon, pine, rosemary, rose, jasmine, tea tree, lemon grass, bergamot, basil, spearmint, juniper, clove, aniseed, fennel, cypress, fir, black pepper, sandalwood, cedarwood, rosewood, cardamom, cinnamon, corander, eucalyptus, geranium, ginger, chamomile, grapefruit, neroli, petitgrain, thyme, vetiver and ylang ylang.

Chemical and physical sunscreens/UV filters include, for example, ethylhexyl-4- methoxycinnamate, 3-benzylidene camphor, 4- methylbenzylidene camphor, aminobenzoic acid, Avobenzone, Benzophenone 4 (Sulisobenzone), Benzophenone 5, Benzophenone 8, Benzophenone-3, Benzylidene camphor sulfonic acid, Bis- ethylhexyloxyphenol methoxyphenol triazine (Escalol S), butyl methoxy dibenzoylmethane, camphor benzalkonium methosulfate, Cinoxate, diethylamino hydroxybenzoyl hexyl benzoate, dioxybenzone, disodium phenyl dibenzimidazole tetrasulfonate, Drometrizole trisi loxane, Ensulizole, ethylhexyl dimethyl PABA, Ethylhexyl methoxycinnamate, ethylhexyl salicylate, ethylhexyl triazone, Homosalate, isoamyl p-methoxycinnamate, Meradimate, menthyl anthranilate, methylene bis-benzotriazolyltetramethylbutylphenol /Bisoctrizole (Tinosorb M), Octocrylene, Octinoxate, PEG-25 PABA, Octisalate, Oxybenzone, Padimate O, Phenylbenzimidazole sulfonic acid, Polyacrylamidomethyl Benzylidene Camphor, Polysilicone- 15, TEA-salicylate, Terephthalylidene dicamphor sulfonic acid, titanium dioxide, Trolamine Salicylate and zinc oxide.

Hair treatment materials include, for example, cationic conditioning agents comprising tertiary and quaternary amino groups (e.g., quaternium-70, quaternium- 80, stearylamidopropyl dimethylamine, behentrimonium methosulfate, dicocodimonium chloride, dicetyldimonium chloride, distearyldimonium chloride hydroxyethyl cetyldimonium phosphate). In addition, they also may include UV and colour protectants (e.g., dimethylpabamidopropyl laurdimonium tosylate), heat protectants and styling polymers (e.g., vinyl pyrrolidone and vinylcaprolactam derivatives, such as PVP vinyl Caprolactam/DMAPA Acrylates Copolymer).

Antimicrobial agents may include, for example, Triclosan™, climbazole, octapyrox, ketoconazole, propiconazole, phthalimoperoxyhexanoic acid (PAP) and quaternary ammonium compounds.

Biocides may include, for example, herbicides such as glyphosphate (N- phosphonomethylglycine), Fomesafen, Glufosinate, Paraquat dichloride and Bentazone.

Fungicides may include, for example, benzimidazole compounds such as benomyl, carbendazim, thiabendazole and thiophanate-methyl; phenylcarbamate compounds such as diethofencarb; dicarboxyimide compounds such as procymidone, iprodione and vinclozolin; azole compounds such as diniconazole, epoxyconazole, tebuconazole, difenoconazole, cyproconazole, flusilazole, flutriafol and triadimefon; acylalanine compounds such as metalaxyl; carboxyamide compounds such as furametpyr, mepronil, flutolanil and tolyfluanid; organophosphate compounds such as tolclofos-methyl, fosetyl aluminum and pyrazophos; anilinopyrimidine compounds such as pyrimethanil, mepanipyrim and cyprodinil; cyanopyrrrole compounds such as fludioxonil and fenpiclonil; antibiotics such as blasticidin-S, kasugamycin, polyoxin and validamycin; methoxyacrylate compounds such as azoxystrobin, kresoxim- methyl and metominostrobin; chlorothalonil; manzeb; captan; folpet; tricyclazole; pyroquilon; probenazole; phthalide; cymoxanil; dimethomorph; S-methylbenzo [ 1 , 2, 3] thiadiazol-7- carbothioate; famoxadone; oxolinic acid; fluaziname; ferimzone; chlobenthiazone; isovaledione; tetrachloroisophthalonitrile; thiophthalimideoxybisphenoxyarsine; 3-iodo-2- propylbutylcarbamate; parahydroxy benzoic ester. Preferred water-insoluble biocides for use in the present invention are antibacterials (for example chlorophenols including Triclosan), antifungals (for example organochlorines including Chlorothalonil and imidazoles such as Ketoconazole and Propiconazole), insecticides (for example pyrethroids, including λ- cyhalothrin) and/or herbicides (for example phenol-ureas including Isoproturon). The invention is also envisaged to be applicable to acaricides, algicides, molluscicides and nematacides.

Nutrient compounds may include, for example, omega oils and fish oils which can give a nutritional or cosmetic benefit such as omega-3, omega-6 and omega-9 fatty acids docosapentaenoic acid, eicosatetraenoic acid, moroctic acid, heneicosapentenoic acid, cod liver oil, halibut liver oil, herring oil, menhaden oil, salmon or trout oils, sardine oil, tuna oil or shark liver oils. Vitamin A and vitamin E.

Insect repellents may include, for example, N,N-dimethyl-m-toluamine (DEET), citronella oil, p-menthane, 3-8-diol, metofluthrin and ethyl 3- [acetyl(butyl)amino]propionate.

Antidandruff agents may include, for example, zinc pyrithione and/or resorcinol monoacetate

Skin lightening agents may include, for example, 4-ethylresorcinol.

Fluorescing agents may include, for example, 2,5-bis(2-benzoxazolyl) thiophene for use on fabrics (such as cotton, nylon, polycotton or polyester) in laundry products.

Skin conditioning agents may include, for example, cholesterol, 3,5,4'-trihydroxy- trans-stilbene (Reservatrol), di-benzoyl peroxide (for acne treatment),

Antifoaming agents may include, for example, isoparrafin and silicone-containing compounds.

Phase change materials, which are compounds which can store and release heat by a phase change in the materials. Examples of these include waxes, such as paraffin waxes, inorganic salts, such as sodium acetate and liquid crystalline materials.

Particularly preferred benefit agents include:

Fragrances and flavours including esters, alcohols, amides, terpenes, aromatic compounds, amines, terpenes, aldehydes, ketones from natural and synthetic sources. Particular fragrance components would be those used widely in the homecare, personal care and industrial applications. The fragrances would typically be present as a mixture of top notes, mid notes and base notes formulated to provide a spectrum of odours.

The benefit agent can be present within the carrier oil or aqueous phase at a concentration of between 0.1 to 100 % w/w. Typically, the benfit agent will be present in the oil phase.

The crosslinking agent

The crosslinking agent is capable of forming a covalent bond with the amphiphilic branched copolymer of the invention. The crosslinker molecule reacts with the amphiphilic branched copolymer of the invention at the boundary of the dispersed phase within the continuous phase, typically at the oil-water interface for oil-in-water encapsulates, and can be introduced to the emulsion mixture by dissolution in the dispersed phase, typically hydrophobic in nature, or the continuous phase, typically hydrophilic and especially aqueous in nature. The crosslinking agent can also be added to the system following emulsification, such as, for example, by dissolving in the continuous phase.

It is a requirement that the crosslinking agent is at least di-functional in order to attain crosslinked structures with the amphiphilic branched copolymer. The crosslinking reaction may also provide additional benefits to the capsule wall such as an increase in wall thickness, rigidity, reduction in porosity, introduction or changes in wall surface charge or provide a means to introduce a surface substantive moiety or a weak link in the capsulate surface. The crosslinking agent can react with the amphiphilic branched copolymer via a number of conventional chemical transformations such as nucleophilic substitution, electrophilic addition, ring-opening reactions, sol-gel reactions (such as the reaction with di-tri-or poly alkoxy silanes), Diels-Alder reactions, ester formation, amide formation, urethane formation, urea formation, carbonate formation, thiol-ene formation, addition polymerisation (from the polymerisation of unreacted or pendant groups on the amphiphilic branched copolymer with an additional monomer or di-or poly-functional monomer) and the 1 + 3 Huisgen cycloaddition reaction, so-called "click chemistry". In particular the reaction with a di-or trifunctional alkoxysilanes are preferred and can react with pendant alkoxysilyl units which may be incorporated in the amphiphilic branched copolymer and suitable additional crosslinking agents include tri and tetra alkoxysilanes such as tetramethyl orthosilicate and tetraethyl orthosilicate, sodium silicate, bis(triethoxysilyl)ethane, bis(trimethoxyethyl)silane, tris-[3- (trimethoxysilyl)propyl]isocyanurate, tris-[3-(triethoxysilyl)propyl]isocyanurate, mercapropropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-octanoylthio-1 - propyl triethoxysilane, aminopropyl trialkoxysilanes such as aminopropyltrimethoxy silane or aminopropyl triethoxysilane, aminopropyl methyl diethoxysilane, Ν-(β- aminoethyl)-Y-aminopropyl trimethoxysilane, N-[N'-(2-aminoethyl)aminoethyl]-3- aminopropyl trimethoxysilane, N-phenyl aminopropyl trimethoxysilane, N-ethyl- aminoisobutyl trimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, ureidopropyl trimethoxysilane, isocyanatopropyl triethoxysilane, isocyanatopropyl trimethoxysilane, glycidoxypropyl trimethoxysilane, glycidoxypropyl triethoxysilane, 3,4 - epoxycyclohexyl - ethyl trimethoxysilane and 3,4 - epoxycyclohexyl - ethyl triethoxysilane.

The crosslinking agent may be present at an amount of 0.1 to 40 % by weight of the amphiphilic branched copolymer. In an embodiment, the cross-linking agent is present at an amount of 0.5 to 30 % by weight of the amphiphilic branched copolymer. In a further embodiment, the cross-linking agent is present at an amount of 1 to 20 % by weight of the amphiphilic branched copolymer.

In certain embodiments, the additional crosslinker is present at stoichiometric amount relative to the functionalisation present on the amphiphilic copolymer. In other embodiments, the functionality present on the polymer may in excess relative to the cross-linking agent. The use of stiochiometirc amounts or situations where the functionality present on the polymer is in an excess may occur, for example, in the case of the reaction of a benzyl halide residue on the amphiphilic branched copolymer, such as that derived from the incorporation of a monomer of vinyl benzyl chloride, and a diamine, such as hexamethylene diamine.

In other embodiments, the additional crosslinker can be present at an amount of 0.1 to 10 times excess by weight. This may be the case, for example, where additional crosslinker can co-polymerise with a functional group in the polymer by a sol-gel chemical reaction, as described previously herein. Emulsion formation

The carrier oil and aqueous phase may be emulsified by any suitable emulsification technique known in the art. For example, the emulsion may be prepared using any common equipment known in the art for this purpose, such as, for example, high shear mixers, homogenisers, ultrasound, membrane emulsification, or microfluidics. A person skilled in the art will understand how to vary the properties of the emulsion by varying equipment used, the shear forces applied, the agitation time etc. to provide an emulsion having the desired properties. A person skilled in the art will also be able to vary the amount of the copolymer defined herein in order to provide the desired level of stabilisation to the emulsion droplets.

Additional emulsifiers may also be used in the emulsification processes described herein. For example, the amphiphilic addition copolymers can also be used in combination with non-functional small molecule or polymeric emulsifiers. In such cases, an emulsion prepared in accordance with the present invention may comprise the cross-linkable copolymer emulsifiers together with a non-reactive emulsifier. Capsule formation occurs via the cross-linking of the copolymers. This is of particular advantage where further functionality needs to be introduced in a capsule via the use of, for example, a further emulsifier. Additionally, the cost of preparing the capsules can be reduced by the use of commodity surfactants or emulsifiers with only minimal changes to existing formulation procedures being required.

Crosslinked polymeric capsule formation

To form polymeric capsules, the process of the invention requires an additional step whereby the crosslinking of the copolymers of the present invention is facilitated.

The branched addition copolymers of the current invention tend to stabilise the emulsions in the pre-capsule formation to a better degree than chemically analogous linear copolymers, by function of their higher molecular weight and increased end- groups and branched architecture. This therefore can lead to better capsule formation in the crosslinking step as it reduces the requirement to complete the crosslinking step in a specific time period, that is the emulsions do not have to be crosslinked immediately as in the case for the linear copolymer encapsulating agents, additionally the branched polymers are synthesised in the carrier medium to be emulsified and encapsulated.

The crosslinking reaction must be able to proceed at the oil/water interface of the emulsion. Suitably, the reaction proceeds under mild conditions and may optionally be catalysed, for example by the addition of an acid or base.

In an embodiment of the invention where the copolymer comprises one or more functional alkoxysilane functional groups, for example by the presence of one or monomers of formula I defined hereinbefore, the cross-linker suitably comprises an alkoxysilane group that is capable of reacting with the alkoxysilane groups present copolymer. This is commonly known as a sol-gel process. This sol-gel reaction can proceed at the oil-water interface and is driven by the hydrolysis of the alkoxysilane functional groups. This process can occur by simply leaving the emulsion to stand for a period of time (typically 2 to 24 hours) or it may be catalysed by the addition of an acid or base.

Thus, the formation of these crosslinks may be facilitated by allowing the emulsion to stand for a period of time, optionally at neutral pH. However, the reaction can be catalysed by the addition of either an acid or a base such as sulfuric, hydrochloric, phosphoric acid or a compound which hydrolyses itself to give an acidic moiety such as δ-gluconolactone or an alkali hydroxide, carbonate or bicarbonate such as sodium hydroxide, sodium carbonate or sodium bicarbonate at pH ranges from 2 to 13. Preferably the emulsion is crosslinked through a change in pH and via a sol-gel reaction of the trialkoxysilyl moieties present in the copolymer.

The particle size of the polymer capsules can be controlled by controlling the size of the emulsion droplets. This can be achieved by techniques known in the art such as varying the production parameters (e.g. agitation speeds, times, temperatures) and the composition of the emulsion (the amount of emulsifier, the nature of the different phases etc.). Preferably the average size of the capsules is smaller than 100 μιη, more preferably smaller than 50 μιη. Preferably the polymer capsule has an internal oil phase and is formed in an aqueous bulk phase.

In a preferred embodiment the capsule comprises a benefit agent, wherein the benefit agent is incorporated in the dispersed phase. In an embodiment, the carrier oil is the dispersed phase and crosslinking of the copolymers forms polymeric capsules encapsulating the dispersed phase.

The polymeric capsule may be configured to release the encapsulated benefit agent in a controlled manner over a period of time or, alternatively, it might be configured to release the encapsulated benefit agent in a more immediate (e.g. a "burst" or "rupture" release profile) manner.

The invention also provides a method of preparing a capsule, comprising a step wherein the copolymer/carrier oil composition incorporating a benefit agent or agent(s) is mixed with a hydrophobic liquid under conditions whereby at least one of the monounsaturated monomer(s) and polyunsaturated monomer(s) and chain transfer agent do not form a non-covalent bond with any other of the monounsaturated monomer(s) and polyunsaturated monomer(s) and chain transfer agent. Under these conditions the polymer is in a non-interacting form. The capsule can be then used to protect or isolate the active agent from the final formulation or to deliver the benefit agent to the desired locus of action by, for example, a "rupture" or "burst release" mechanism.

The polymeric capsules formed can be further post-modified with reagents to provide, for example, increased stability or surface recognition. Reactive links can be introduced into the crosslinked structure in order to facilitate rupturing of the capsules in response to certain environmental conditions, for example via a change in temperature, ionic strength or pH. Similarly, the capsules can be crosslinked together to give higher order structures such as "beads" or monoliths where the emulsion droplets have been aggregated prior to the final crosslinking step. Once formed, the contents of the capsules can also be removed by a washing material to obtain hollow receptacles suitable for filling with other benefit agent materials, or for use in their own right in for example composites where they could be utilised as an additive to alter the opacity, dielectric constant or strength of a composite, coating or film.

In embodiments where the branched addition copolymers have associating functionality, such as H-bonding groups, they may aggregate in solution upon the application of an external trigger such as in the case of capsules decorated with carboxylic acid functionality. In this case, the formed capsules may assemble via hydrogen-bonding (with inherent changes in hydrophobicity) when below the pKa of the acid group and reversibly disassemble upon the application of an increase in pH.

The encapsulation of hydrophobic benefit agents is of industrial relevance where a hydrophobic component is required to be delivered from, formulated in, or isolated from, an aqueous environment. For example the crosslinked capsule may protect a benefit agent compound from a hydrophilic formulation where the bulk aqueous environment can lead to degradation of the hydrophobic material or is, for example, rich in additional surfactants which can affect the performance of the hydrophobic benefit agent. The capsule may also be post-modified in order to improve the selectivity of the capsule, such as the covalent attachment of surface-substantive or bio-active materials, for example in the specific delivery of pharmaceutical agents. The capsules may also be designed to assemble and disassemble upon changes in the aqueous environment, such as pH, this is particularly desirable in the preparation of a "capsule concentrate" in the associated form for transportation purposes and formulation dilution at the required destination, that is On-site'. The payload of the capsule can also be washed-out to yield hollow spheroids which can be filled or used in their own right as, for example, in composite materials. Examples include but are not limited to: the encapsulation of bioactive compounds such as pharmaceuticals or agrochemicals; nutritional agents such as vitamins; cosmetics, catalysts, dyes, pigments, flavours, fragrances, lubricating oils, emollients, natural oils and waxes, paints, inks, coatings, sealants and tissue engineering scaffolds.

The statistical branched amphiphilic copolymer

Typically, the statistical branched amphiphilic copolymer further comprises a residue of a chain transfer agent and optionally a residue of an initiator.

In an aspect of the invention, the statistical branched amphiphilic copolymer is as defined above and further comprises a residue of a chain transfer agent and a residue of an initiator and wherein at least one of the monounsatu rated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophilic residue; and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophobic residue. The amphiphilic copolymers of the present invention are statistical, that is to say, random in structure. The distribution of the comonomers in the polymer structure is not controlled and is determined through factors such as relative monomer concentrations and their respective reactivity ratios. This negates the requirement to use controlled polymerisation techniques to achieve, for example, block copolymer structures or to control their molecular weights or polydispersities. Additionally, the polymerisation is through a conventional free-radical technique and the polymers can, in some instances, be prepared directly in the carrier medium without any further purification. This can negate the requirement to prepare the polymers in a solvent system and isolate, or purify, the polymer product providing a solution of the polymer encapsulating agent which can be directly emulsified in conjunction with an additional benefit agent payload. This process can also be used where the benefit agent is a liquid in which the polymer can be synthesised, thereby removing a number of steps from the industrial process.

The statistical branched amphiphilic copolymers are effective emulsifiers. The copolymer stabilises the emulsion droplets that are formed and can then be crosslinked by reaction with crosslinking agent in order to form polymeric capsules or shells around the dispersed emulsion droplets, effectively encapsulating the dispersed emulsion droplets (and any benefit agent that is contained therein).

The emulsions stabilised may be oil-in-water or water-in-oil, or so-called double emulsions (water-in-oil-in-water or oil-in-water-in-oil emulsions). Typically, the emulsion will be an oil-in-water emulsion.

The copolymers stabilise the emulsions efficiently at low concentrations without the need for additional co-stabilisers or surfactants. Once the emulsion is formed, the copolymer can be chemically crosslinked to form a polymeric capsule or shell. One or more species or benefit agents may be present in the dispersed phase of the emulsion and these benefit agents can be encapsulated within the polymeric capsule or shell that is formed at the oil-water interface of the emulsion. The chemical crosslinking is achieved by the reaction of the functional groups present on the copolymer chains with other functional groups present on adjacent copolymer chains and/or with functional groups present on the crosslinking agent. It will be appreciated that the reaction of these functional groups covalently binds adjacent copolymer molecules together to form a crosslinked polymer capsule or shell. The copolymers of the invention are amphiphilic addition copolymers. Amphiphilic addition copolymers are especially useful for stabilising oil-in-water emulsions. In particular branched copolymers are especially useful as they have been shown to form extremely stable emulsions at low concentrations to their high molecular weight, branched architectures and chemical composition. These branched copolymers effectively stabilise oil-in-water emulsions more effectively than equivalent linear polymers.

The selection of appropriate functional groups in the copolymer structure results in a functional copolymer emulsifier which can form inter-molecular crosslinks with the additional crosslinking agent and/or directly with adjacent copolymer molecules.

The amphiphilic copolymers according to the present invention are branched. The branched, non-crosslinked addition amphiphilic copolymers may include statistical, graft, gradient and alternating branched copolymers. The copolymers comprise at least two chains which are covalently linked by a bridge (typically other than at their ends), which is to be understood as a polymer wherein a sample of said polymer comprises on average at least two chains which are covalently linked by a bridge other than at their ends. When a sample of the polymer is prepared, there may be accidentally some polymer molecules which are unbranched, which is inherent to the production method (addition polymerisation process). For the same reason, a small quantity of the polymer will not have a chain transfer agent at a chain end.

To function in the desired manner, the addition copolymer of the present invention must have certain attributes as discussed further below.

Amphiphilicity: The addition copolymer must be amphiphilic, i.e. it contains moieties capable of associating with the dispersed (internal) and continuous (bulk) phases of the emulsion. That is the copolymer must contain hydrophilic and hydrophobic units within the copolymer structure. Hydrophobicity is typically achieved by using hydrophobic monomers such as alkyl-functional monomers, e.g. an alkyl methacrylate, and/or via a hydrophobic chain transfer agent such as an alkyl mercaptan, e.g. dodecanethiol. Additionally, the copolymer must have hydrophilic functionality, again typically achieved by the use of hydrophilic monomers, for example the monomer could be neutral, for example poly(ethylene glycol)-functional monomers such as mono-methoxypoly(ethylene glycol) methacrylate, or the monomer could be charged in nature, such as acrylic or methacrylic acid or weakly basic monomers, e.g. dimethyl or diethylaminoethyl methacrylate or their respective salts. The hydrophilic unit can be responsive in nature whereby the hydrophilicity can be altered by an external stimulus such as pH or temperature, such as in the case of N-isopropylacrylamide. The hydrophilic and hydrophobic units could also be introduced through the ethylenically polyunsaturated monomer (brancher) or chain transfer agent where applicable.

In an embodiment, the hydrophilic monomer may be of high molecular weight, such that at least one of the ethylenically monounsatu rated monomer, the ethylenically polyunsaturated monomer and/or the chain transfer agent is a hydrophilic residue having a molecular weight of at least 400 Daltons (e.g. at least 1 ,000 Daltons). In an embodiment, the hydrophilic component is derived from the ethylenically polyunsaturated monomer. In another embodiment, the hydrophilic component is the chain transfer agent. In a preferred embodiment, the hydrophilic component is the ethylenically monounsatu rated monomer. In all cases, a combination of hydrophilic components is possible and may be desirable.

Higher molecular weight hydrophobic species are typically more hydrophobic than lower molecular weight hydrophobic species. Preferably, the hydrophobic component is derived from the polyunsaturated monomer, more preferably from the chain transfer agent (during conventional free-radical polymerisation) or the initiator, but most preferably from a monounsaturated monomer. In all cases, a combination of hydrophobic components is possible and may be desirable.

Functionality: The addition copolymer must also possess one or more functional groups capable of reacting with functional groups present in the crosslinking agent and/or functional groups present on adjacent copolymer molecules. In an embodiment, this functionality is achieved by the inclusion of alkoxysilane functional groups, which react with other alkoxysilane functional groups present on adjacent copolymer molecules and/or the crosslinking agent via a sol-gel process. However, other functional groups may be present in place of, or in addition to the alkoxysilane functional groups, including those which can form intermolecular ester, amide, urethane, urea linkages or those associated by a nucleophilic substitution or addition reactions, for example the reaction of an epoxide with a nucleophile such as an amine or an alkoxide which can occur through the reaction of a residue of glycidyl(meth)acrylate with an amine residue derived from aminoethyl(meth)acrylate or the reaction of a benzyl halide moiety such as a residue derived from a vinylbenzyl chloride monomer with an amine moiety such as that derived from a residue from a dimethylamino ethyl (methacrylate) monomer.

Branched addition polymers: Branched polymers and copolymers are polymer molecules of a finite size which are branched. Branched polymers are soluble and differ from crosslinked polymer networks which tend towards an infinite size having interconnected molecules and which are generally not soluble but often swellable. In some instances, branched polymers have advantageous properties when compared to analogous linear polymers. For instance, solutions of soluble branched polymers are normally less viscous than solutions of analogous linear polymers. Moreover, higher molecular weights of branched copolymers can be solubilised more easily than those of corresponding linear polymers. Also, branched copolymers tend to have more end groups than a linear polymer and therefore generally exhibit strong surface-modification properties. Thus, branched copolymers are useful components of many compositions utilised in a variety of fields.

Branched polymers are usually prepared via a step-growth mechanism through the polycondensation of monomers and are usually limited via the chemical functionality of the resulting polymer and the molecular weight. In an addition polymerisation process, a one-step process can be used in which a multifunctional monomer is used to provide functionality in the polymer chain from which polymer branches may grow. However, a limitation on the use of conventional one-step processes (in the absence of a chain transfer agent) is that the amount of multifunctional monomer must be carefully controlled, usually to substantially less than 0.5% w/w in order to avoid extensive crosslinking of the polymer and the formation of insoluble gels or hydrogels. It is difficult to avoid crosslinking using this method, especially in the absence of a solvent as diluent and/or at high conversion of monomer to polymer. The reactive amphiphilic addition copolymers in the present invention are typically soluble materials, that is they form isotropic solutions in hydrophilic or hydrophobic solvents, which have been designed to emulsify hydrophobic or hydrophilic materials in an aqueous or hydrophobic bulk medium and undergo chemical crosslinking reaction to yield capsules. Branched addition amphiphilic copolymers have been shown to efficiently emulsify and ultimately crosslink around a hydrophobic internal phase to form capsules or aggregated crosslinked structures. In order for the branched addition polymers to be suitable for use in encapsulation technologies the polymer must possess a number of structural components. Typically, the branched addition copolymers are used to emulsify, and ultimately encapsulate, a hydrophobic oil in an aqueous bulk phase. Essentially the branched addition polymer must be capable of forming a stable emulsion which can then be further reacted to give a stable crosslinked polymeric capsule. It is preferred if this reaction can occur without the addition of a further functional monomer; that is the branched addition copolymer emulsifier contains a functional group which can self-react to give a crosslinked shell around the capsule. To avoid tedious and costly purification steps the branched addition polymers can be prepared within the carrier oil phase and used without further isolation in the emulsification and encapsulation processes.

Post emulsification: The post-emulsification crosslinking reaction takes place through reaction of functional groups present within the copolymer emulsifiers with an additional crosslinking agent. Thus, the copolymer acts as both emulsifier and a polymeric capsule former. Additionally, the emulsion or polymer capsule can be further chemically reacted post-emulsification, or post-encapsulation, to give further chemical species at the surface of the emulsion or polymer capsule which may be of benefit, for example in improved substrate affinity. Crosslinking can occur between copolymer residues on the same interface to form capsules or between copolymer emulsifiers on adjacent interfaces to form monoliths.

As indicated above, the statistical branched amphiphilic copolymer comprises at least two polymeric chains which are covalently linked by a bridge. The at least two chains are formed by the polymerisation of one or more ethylenically monounsaturated monomers and the bridge or bridges is/are formed by the polymerisation of at least one ethylenically polyunsaturated monomer. The copolymer also comprises one or more functional groups capable of reacting with functional groups present on the crosslinking agent.

Suitably, at least one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) is a hydrophilic residue; and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) is a hydrophobic residue. Suitably, the mole ratio of polyunsaturated monomer(s) to monounsaturated monomer(s) is 1 :100 to 1 :4.

It will be appreciated that a number of different functional groups may be present on the copolymer and the selection of suitable reactive functional groups capable of reacting with functional groups present on the crosslinking agent will be readily apparent to a person skilled in the art. For example, the copolymer may comprise functional groups capable of reacting with the crosslinking agent by a variety of different reaction chemistries such as, for example, nucleophilic substitution, electrophilic addition, ring-opening reactions, sol-gel reactions (such as the reaction between di-tri-or poly alkoxy silanes), Diels-Alder reactions, ester formation, amide formation, urethane formation, urea formation, carbonate formation, thiol-ene formation, addition polymerisation (from the polymerisation of unreacted or pendant groups on the amphiphilic branched copolymer with an additional monomer or di-or poly-functional monomer) and the 1 + 3 Huisgen cycloaddition reaction, so-called "click chemistry".

Thus, the copolymer may, for example, comprise one or more functional groups capable of reacting with functional groups on the crosslinking agent to form ester, amide, urethane, urea or thiol linkages, or other linkages associated with a nucleophilic substitution or addition reactions, for example the reaction of an epoxide with a nucleophile such as an amine or an alkoxide (which can occur through the reaction of a residue of glycidyl(meth)acrylate with an amine residue derived from aminoethyl(meth)acrylate or the reaction of a benzyl halide moiety such as a residue derived from a vinylbenzyl chloride monomer with an amine moiety such as that derived from a residue from a dimethylamino ethyl (methacrylate) monomer. Alternatively, the reaction with an acetoacetate functionality with an amine or other reactive group duch as through the incorporation of a residue derived from 2- (methacrylyoxy)ethyl acetoacetate and a diamine such as hexamethylene diamine. Thus, suitable functional groups may be selected from amines, alcohols, thiols, ketones, carboxylic acids, acid chlorides, halogens, alkoxysilanes, epoxides, and acetoacetates.

In particular the reaction between di- or tri-functional alkoxysilanes present on the copolymer with di-, tri- or tetra-alkoxysilanes present in crosslinking agent are preferred. To facilitate such a reaction, monomers bearing pendant alkoxysilyl groups may be incorporated in the amphiphilic branched copolymer structure. These alkoxysilyl groups are typically (1 -2C)alkoxysilyl groups. These moieties may react with suitable additional crosslinking agents, including tri- and tetra-alkoxysilanes such as tetramethyl orthosilicate and tetraethyl orthosilicate, sodium silicate, bis(triethoxysilyl)ethane, bis(trimethoxyethyl)silane, tris-[3-

(trimethoxysilyl)propyl]isocyanurate, tris-[3-(triethoxysilyl)propyl]isocyanurate, mercapropropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-octanoylthio-1 - propyl triethoxysilane, aminopropyl trialkoxysilanes such as aminopropyltrimethoxy silane or aminopropyl triethoxysilane, aminopropyl methyl diethoxysilane, Ν-(β- aminoethyl)-Y-aminopropyl trimethoxysilane, N-[N'-(2-aminoethyl)aminoethyl]-3- aminopropyl trimethoxysilane, N-phenyl aminopropyl trimethoxysilane, N-ethyl- aminoisobutyl trimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, ureidopropyl trimethoxysilane, isocyanatopropyl triethoxysilane, isocyanatopropyl trimethoxysilane, glycidoxypropyl trimethoxysilane, glycidoxypropyl triethoxysilane, 3,4 - epoxycyclohexyl - ethyl trimethoxysilane and 3,4 - epoxycyclohexyl - ethyl triethoxysilane.

In an embodiment, the copolymer comprises one or more alkoxysilane groups which are capable of reacting with alkoxysilane groups present in the crosslinking agent via a sol-gel process.

The ethylenically monounsaturated monomer

The ethylenically monounsaturated or monofunctional monomer may be any suitable monounsaturated monomer known in the art.

The ethylenically monounsaturated monomer or monomers may be hydrophilic, hydrophobic, amphiphilic, anionic, cationic, neutral or zwitterionic in nature. The monounsaturated monomers may be selected from, but not limited to, monomers such as vinyl acids, vinyl acid esters, vinyl aryl compounds, vinyl acid anhydrides, vinyl amides, vinyl ethers, vinyl amines, vinyl aryl amines, vinyl nitriles, vinyl ketones, and derivatives of the aforementioned compounds as well as corresponding allyl variants thereof. Other suitable monounsaturated monomers include hydroxyl- containing monomers and monomers which can be post-reacted to form hydroxyl groups, acid-containing or acid-functional monomers, zwitterionic monomers and quaternised amino monomers. Oligomeric, polymeric and di- or multi-functionalised monomers may also be used, especially oligomeric or polymeric (meth)acrylic acid esters such as mono(alk/aryl) (meth)acrylic acid esters of poly(alkyleneglycol) or poly(dimethylsiloxane) or any other mono-vinyl or allyl adduct of a low molecular weight oligomer. Mixtures of more than one monomer may also be used to give statistical, graft, gradient or alternating copolymers.

Vinyl acids and derivatives thereof include (meth)acrylic acid, fumaric acid, maleic acid, itaconic acid and acid halides thereof such as (meth)acryloyl chloride. Vinyl acid esters and derivatives thereof include C1-C20 alkyl(meth)acrylates (linear & branched) such as methyl (meth)acrylate, stearyl (meth)acrylate and 2-ethyl hexyl (meth)acrylate, aryl(meth)acrylates such as benzyl (meth)acrylate, tri(alkyloxy)silylalkyl(meth)acrylates such as trimethoxysilylpropyl(meth)acrylate and activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate. Vinyl aryl compounds and derivatives thereof include styrene, acetoxystyrene, styrene sulfonic acid, vinyl pyridine, vinylbenzyl chloride and vinyl benzoic acid. Vinyl acid anhydrides and derivatives thereof include maleic anhydride. Vinyl amides and derivatives thereof include (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidone, N-vinyl formamide, (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]dimethyl ammonium chloride, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide. Vinyl ethers and derivatives thereof include methyl vinyl ether. Vinyl amines and derivatives thereof include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, mono-t-butylaminoethyl (meth)acrylate, morpholinoethyl(meth)acrylate and monomers which can be post- reacted to form amine groups, such as vinyl formamide. Vinyl aryl amines and derivatives thereof include vinyl aniline, vinyl pyridine, N-vinyl carbazole and vinyl imidazole. Vinyl nitriles and derivatives thereof include (meth)acrylonitrile. Vinyl ketones and derivatives thereof include acreolin.

Hydroxyl-containing monomers include vinyl hydroxyl monomers such as hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, glycerol mono(meth)acrylate and sugar mono(meth)acrylates such as glucose mono(meth)acrylate. Monomers which can be post-reacted to form hydroxyl groups include vinyl acetate, acetoxystyrene and glycidyl (meth)acrylate. Acid-containing or acid functional monomers include (meth)acrylic acid, styrene sulfonic acid, vinyl phosphonic acid, vinyl benzoic acid, maleic acid, fumaric acid, itaconic acid, 2- (meth)acrylamido 2-ethyl propanesulfonic acid, mono-2-((meth)acryloyloxy)ethyl succinate and ammonium sulfatoethyl (meth)acrylate. Zwitterionic monomers include (meth)acryloyloxyethylphosphoryl choline and betaines, such as [2- ((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide. Quaternised amino monomers include (meth)acryloyloxyethyltri-(alk/aryl)ammonium halides such as (meth)acryloyloxyethyltrimethyl ammonium chloride.

Oligomeric and polymeric monomers include oligomeric and polymeric (meth)acrylic acid esters such as mono(alk/aryl)oxypoly(alkyleneglycol)(meth)acrylates and mono(alk/aryl)oxypoly(dimethylsiloxane)(meth)acrylates. These esters include monomethoxyoligo(ethyleneglycol) mono(meth)acrylate, monomethoxyoligo(propyleneglycol) mono(meth)acrylate, monohydroxyoligo(ethyleneglycol) mono(meth)acrylate, monohydroxyoligo(propyleneglycol) mono(meth)acrylate, monomethoxy poly(ethyleneglycol) mono(meth)acrylate, monomethoxy poly(propyleneglycol) mono(meth)acrylate, monohydroxy poly(ethyleneglycol) mono(meth)acrylate and monohydroxy poly(propyleneglycol) mono(meth)acrylate. Further examples include vinyl or allyl esters, amides or ethers of pre-formed oligomers or polymers formed via ring-opening polymerisation such as oligo(caprolactam), oligo(caprolactone), poly(caprolactam) or poly(caprolactone), or oligomers or polymers formed via a living polymerisation technique such as poly(1 ,4-butadiene).

The corresponding allyl monomers to those listed above can also be used where appropriate.

Further examples of suitable additional monounsaturated monomers are:

Amide-containing monomers such as, for example, (meth)acrylamide, N-(2- hydroxypropyl)methacrylamide, N,N'-dimethyl(meth)acrylamide, N and/or N'-di(alkyl or aryl) (meth)acrylamide, N-vinyl pyrrolidone, [3-((meth)acrylamido)propyl] trimethyl ammonium chloride, 3-(dimethylamino)propyl(meth)acrylamide, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide; (Meth)acrylic acid and derivatives thereof such as (meth)acrylic acid, (meth)acryloyl chloride (or any halide), (alkyl/aryl)(meth)acrylate, functionalised oligomeric or polymeric monomers such as monomethoxyoligo(ethyleneglycol) mono(meth)acrylate, monomethoxyoligo(propyleneglycol) mono(meth)acrylate, monohydroxyoligo(ethyleneglycol) mono(meth)acrylate, monohydroxyoligo(propyleneglycol) mono(meth)acrylate.monomethoxy poly(ethyleneglycol) mono(meth)acrylate, monomethoxy poly(propyleneglycol) mono(meth)acrylate, monohydroxy poly(ethyleneglycol) mono(meth)acrylate, monohydroxy poly(propyleneglycol) mono(meth)acrylate, glycerol mono(meth)acrylate and sugar mono(meth)acrylates such as glucose mono(meth)acrylate; vinyl amines such as, for example, aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, mono-t-butylamino (meth)acrylate, morpholinoethyl(meth)acrylate, vinyl aryl amines such as vinyl aniline, vinyl pyridine, N-vinyl carbazole, vinyl imidazole, and monomers which can be post-reacted to form amine groups, such as N-vinyl formamide; vinyl aryl monomers such as, for example, styrene, vinyl benzyl chloride, vinyl toluene, -methyl styrene, styrene sulfonic acid and vinyl benzoic acid; vinyl hydroxyl monomers such as, for example, hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, glycerol mono(meth)acrylate or monomers which can be post- functionalised into hydroxyl groups such as vinyl acetate, acetoxy styrene and glycidyl (meth)acrylate; acid-containing monomers such as, for example, (meth)acrylic acid, styrene sulfonic acid, vinyl phosphonic acid, vinyl benzoic acid, maleic acid, fumaric acid, itaconic acid, 2-(meth)acrylamido 2-ethyl propanesulfonic acid and mono-2- ((meth)acryloyloxy)ethyl succinate or acid anhydrides such as maleic anhydride; zwitterionic monomers such as, for example, (meth)acryloyloxyethylphosphoryl choline and betaine-containing monomers, such as [2-((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide; quaternised amino monomers such as, for example, (meth)acryloyloxyethyltrimethyl ammonium chloride. The corresponding allyl monomer, where applicable, can also be used in each case.

Functional monomers, i.e. monomers with reactive pendant groups which can be post or pre-modified with another moiety following polymerisation, or which take part in the intra- or inter-molecular crosslinking reaction to form the encapsulate wall can also be used such as glycidyl (meth)acrylate, (meth)acryloyl chloride, maleic anhydride, hydroxyalkyl (meth)acrylates, (meth)acrylic acid, vinylbenzyl chloride, activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2-isocyonatoethyl (meth)acrylate, ethyleneglycol dicyclopentenyl ether methacrylate or 5-norbornene-2-methanol methacrylate, 2-(methacrylyoxy)ethyl acetoacetate and acetoxystyrene.

Macromonomers (monomers having a molecular weight of at least 1 ,000 Daltons) are generally formed by linking a polymerisable moiety, such as a vinyl or allyl group, to a pre-formed monofunctional polymer via a suitable linking unit such as an ester, an amide or an ether. Examples of suitable polymers include mono functional poly(alkyleneglycol) such as monomethoxy poly(ethyleneglycol) or monomethoxy poly(propyleneglycol), silicones such as poly(dimethylsiloxane)s, polymers formed by ring-opening polymerisation such as poly(caprolactone) or poly(caprolactam) or mono-functional polymers formed via living polymerisation such as poly(1 ,4- butadiene).

Preferred macromonomers include monomethoxy poly(ethyleneglycol) mono(methacrylate), monomethoxy poly(propyleneglycol) mono(methacrylate) and mono(meth)acryloxypropyl-terminated poly(dimethylsiloxane).

Hydrophilic monounsaturated monomers include (meth)acryloyl chloride, N- hydroxysuccinamido (meth)acrylate, styrene sulfonic acid, maleic anhydride, (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidinone, N-vinyl formamide, quaternised amino monomers such as (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]trimethyl ammonium chloride and (meth)acryloyloxyethyltrimethyl ammonium chloride, 3-[N-(3-

(meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonat e, methyl (meth)acrylamidoglycolate methyl ether, glycerol mono(meth)acrylate, monomethoxy and monohydroxyoligo(ethyleneglycol) (meth)acrylate, sugar mono(meth)acrylates such as glucose mono(meth)acrylate, (meth)acrylic acid, vinyl phosphonic acid, fumaric acid, itaconic acid, 2-(meth)acrylamido 2-ethyl propanesulfonic acid, mono- 2-((meth)acryloyloxy)ethyl succinate, ammonium sulfatoethyl (meth)acrylate, (meth)acryloyloxyethylphosphoryl choline and betaine-containing monomers such as [2-((meth)acryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide.

Preferred hydrophobic monounsaturated monomers include: methyl (meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, t-butyl(meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, vinylbenzyl chloride, methyl vinyl ether, vinyl formamide, (meth)acrylonitrile, styrene.

Preferred hydrophilic monounsaturated monomers include: (meth)acrylic acid, fumaric acid, maleic acid, itaconic acid, N-hydroxysuccinamido (meth)acrylate, acetoxystyrene, styrene sulfonic acid, vinyl pyridine, and vinyl benzoic acid, maleic anhydride, (meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-vinyl pyrrolidone, N-vinyl formamide, (meth)acrylamidopropyltrimethyl ammonium chloride, [3-((meth)acrylamido)propyl]dimethyl ammonium chloride, 3-[N-(3- (meth)acrylamidopropyl)-N,N-dimethyl]aminopropanesulfonate, methyl (meth)acrylamidoglycolate methyl ether and N-isopropyl(meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate, morpholinoethyl(meth)acrylate, acreolin, poly(ethyleneglycol) (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxy propyl (meth)acrylate, 2-(meth)acrylamido 2-ethyl propanesulfonic acid, (meth)acryloyloxyethyltrimethyl ammonium chloride.

Preferred reactive monofunctional monomers include: trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, allyl methacrylate, ethyleneglycol dicyclopentenyl ether methacrylate or 5-norbornene-2-methanol methacrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2-isocyonatoethyl (meth)acrylate and vinylbenzyl chloride.

In an embodiment, the ethylenically monounsaturated or monofunctional monomer component comprises one or more monomers that bear one or more functional groups capable of reacting with the crosslinking agent to crosslink the copolymer molecules at the oil/water interface of the emulsion. In an embodiment, the monounsatu rated monomer component comprises one or more monomers comprising a functional alkoxysilane moiety that is capable of reacting with a functional alkoxysilane moiety present on the crosslinking agent.

In a particular embodiment, the copolymer comprises one or more monounsatu rated crosslinking monomers formed by the polymerisation of a monomer of Formula (1 ):

H ₂ C=CH(Ri)-C(O)-O-R2-Si(OR3)3

Formula (1 ) wherein Ri is H or an optionally substituted (1 -4C)alkyl group; R2 is a (2- 8C)alkylene group and R3 is an optionally substituted (1 -4C)alkyl group.

Suitably, Ri is H or (1 -2C)alkyl. In an embodiment, Ri is H or methyl. In a particular embodiment, Ri is H. In a further embodiment, Ri is methyl.

Suitably, R2 is a (2-4C)alkylene. In a particular embodiment, R2 is ethylene or propylene, particularly propylene.

Suitably, R3 is (1 -3C)alkyl and, more suitably, R3 is (1 -2C)alkyl. In an embodiment, R3 is methyl. In an embodiment, R3 is ethyl.

Suitable tri(alkoxy)silylalkylacrylates or tri(alkoxy)silylalkyl(meth)acrylates are known in the art. Particular examples include trimethoxysilylpropylacrylate, triethoxysilylpropylacrylate, trimethoxysilylpropyl(meth)acrylate and triethoxysilylpropyl(meth)acrylate.

In an embodiment, the co-polymer comprises one or more monomers bearing functional groups that are selected from a group of formula I as defined above, glycidyl (meth)acrylate, (meth)acryloyl chloride, maleic anhydride, hydroxyalkyl (meth)acrylates, (meth)acrylic acid, vinylbenzyl chloride, activated esters of (meth)acrylic acid such as N-hydroxysuccinamido (meth)acrylate, acetoacetoxyethyl (meth)acrylate, allyl (meth)acrylate, urethane (meth)acrylates such as 2- isocyonatoethyl (meth)acrylate, ethyleneglycol dicyclopentenyl ether methacrylate, 5- norbornene-2-methanol methacrylate, 2-(methacrylyoxy)ethyl acetoacetate and/or acetoxystyrene.

In an embodiment, the one or more monomers bearing functional groups (e.g. the crosslinking monomer of formula I) accounts for 10 to 100 mole % of the ethylenically monounsaturated monomer component of the copolymer. More typically, the one or more monomers bearing functional groups (e.g. the crosslinking monomer of formula I) accounts for 30 to 100 mole % of the ethylenically monounsaturated monomer component of the copolymer. In other embodiments of the invention, the one or more monomers bearing functional groups (e.g. the crosslinking monomer of formula I) accounts for 50 to 100 mole %, or 60 to 100 mole %, or 70 to 100 mole %, or 80 to 100 mole %, or 70 to 98 mole %, or 80 to 95 mole % of the ethylenically monounsaturated monomer component of the copolymer.

In an embodiment, the monounsaturated monomer component comprises the one or more monomers bearing functional groups (e.g. the crosslinking monomer of formula I) and an additional monounsaturated monomer. In such embodiments, the additional ethylenically monounsaturated monomers may account for 0 to 90 mole % of the ethylenically monounsaturated monomer component of the copolymer. More typically, the additional ethylenically monounsaturated monomers will account for 0 to 70 mole % of the ethylenically monounsaturated monomer component of the copolymer. In other embodiments of the invention, the additional ethylenically monounsaturated monomers may account for 0 to 50 mole %, or 0 to 40 mole %, or 0 to 30 mole %, or 0 to 20 mole %, or 2 to 30 mole %, or 5 to 20 mole % of the ethylenically monounsaturated monomer component of the copolymer.

The ethylenically polyunsaturated monomer

The ethylenically polyunsaturated (multifunctional) monomer (also referred to herein as "brancher(s)") may comprise a molecule containing at least two vinyl groups which may be polymerised via addition polymerisation. The monomers may be hydrophilic, hydrophobic, amphiphilic, neutral, cationic, zwitterionic, oligomeric or polymeric. Such monomers are often known as crosslinking agents in the art and may be prepared by reacting any di- or multifunctional monomer with a suitably reactive monomer. Examples include di- or multivinyl esters, di- or multivinyl amides, di- or multivinyl aryl compounds, di- or multivinyl alk/aryl ethers. Typically, in the case of oligomeric or polymeric di- or multifunctional branchers, a linking reaction is used to attach a polymerisable moiety to a di- or multifunctional oligomer or polymer. The brancher may itself have more than one branching point, such as T-shaped divinylic oligomers or polymers. In some cases, more than one ethylenically polyunsaturated (multifunctional) monomer may be used.

The corresponding allyl monomers to those listed above can also be used where appropriate.

Preferred multifunctional monomers include but are not limited to: divinyl aryl monomers such as divinyl benzene; (meth)acrylate diesters such as ethylene glycol di(meth)acrylate, propyleneglycol di(meth)acrylate and 1 ,3-butylenedi(meth)acrylate; poly(alkyleneglycol) di(meth)acrylates such as tetraethyleneglycol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and poly(propyleneglycol) di(meth)acrylate; divinyl (meth)acrylamides such as methylene bisacrylamide; butanediol di(meth)acrylate, hexanediol di(meth)acrylate, silicone-containing divinyl esters or amides such as (meth)acryloxypropyl-terminated poly(dimethylsiloxane); divinyl ethers such as poly(ethyleneglycol)divinyl ether; and tri-, tetra- or hexyl- (meth)acrylate esters such as trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerithritol hexa(meth)acrylate or glucose di- to penta(meth)acrylate. Further examples include vinyl or allyl esters, amides or ethers of pre-formed oligomers or polymers formed via ring-opening polymerisation such as oligo(caprolactam), oligo(caprolactone), poly(caprolactam) or poly(caprolactone), or oligomers or polymers formed via a living polymerisation technique such as oligo- or poly(1 ,4-butadiene).

Macrocrosslinkers or macrobranchers (multifunctional monomers having a molecular weight of at least 1 ,000 Daltons) are generally formed by linking a polymerisable moiety, such as a vinyl or aryl group, to a pre-formed multifunctional polymer via a suitable linking unit such as an ester, an amide or an ether. Examples of suitable polymers include di-functional poly(alkylene oxides) such as poly(ethyleneglycol) or poly(propyleneglycol), silicones such as poly(dimethylsiloxane)s, polymers formed by ring-opening polymerisation such as poly(caprolactone) or poly(caprolactam) or poly- functional polymers formed via living polymerisation such as poly(1 ,4-butadiene).

Preferred macrobranchers include poly(ethyleneglycol) di(meth)acrylate, poly(propyleneglycol) di(meth)acrylate, methacryloxypropyl-terminated poly(dimethylsiloxane), poly(caprolactone) di(meth)acrylate and poly(caprolactam) di(meth)acrylamide. Branchers include methylene bisacrylamide, glycerol di(meth)acrylate, glucose di- and tri(meth)acrylate, oligo(caprolactam) and oligo(caprolactone). Multi end- functionalised hydrophilic polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group.

Further branchers include divinyl benzene, (meth)acrylate esters such as, for example, ethyleneglycol di(meth)acrylate, propyleneglycol di(meth)acrylate and 1 ,3- butylene di(meth)acrylate, oligo(ethylene glycol) di(meth)acrylates such as tetraethylene glycol di(meth)acrylate, tetra- or tri- (meth)acrylate esters such as pentaerthyritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylateand glucose penta(meth)acrylate. Multi end-functionalised hydrophobic polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group.

Multifunctional responsive polymers may also be functionalised using a suitable polymerisable moiety such as a (meth)acrylate, (meth)acrylamide or styrenic group such as polypropylene oxide) di(meth)acrylate.

Preferred polyunsaturated monomers or branchers include: divinyl benzene, ethyleneglycol di(meth)acrylate, 1 ,4 butanediol di(methacrylate), hexane diol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and N, N'- methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and dipentaerithritol hexa(meth)acrylate.

The molar ratio of ethylenically polyunsaturated monomer component to the ethylenically monounsatu rated monomer component is suitably 1 :100 to 1 :4. More typically, the molar ratio of ethylenically polyunsaturated monomer component to the ethylenically monounsaturated monomer component is 1 :20 to 1 :4, or 1 :20 to 1 :5.

The formation of the statistical branched amphiphilic copolymer

The statistical branched amphiphilic copolymer can be prepared by any suitable technique known in the art. For example, they may be prepared by the techniques described in WO2013/024307, the entire contents of which are incorporated herein by reference. Suitably, the statistical branched amphiphilic copolymer can be prepared by an addition polymerisation process. Such a process typically comprises mixing together:

(a) one or more ethylenically monounsatu rated monomers;

(b) one or more ethylenically polyunsaturated monomers;

(c) a chain transfer agent; and

(d) an initiator; and subsequently reacting said mixture to form a branched copolymer.

Suitably, from 1 to 25 mole % (based on the number of moles of monofunctional monomer(s)) the one or more polyunsaturated monomers is present.

Solvent

The reaction may be conducted in any suitable solvent for a polymerisation process. Examples of suitable solvents include alcohols (such as methanol, ethanol, propanol, etc.), tetrahydrofuran, aromatic compounds (such as benzene, toluene, xylene etc.). or Solveso esters (such as ethyl acetate, butyl acetate etc.), a carrier oil as defined hereinbefore, or, for hydrophilic polymers, water or an aquous solution could also be used.

Following the reaction, the copolymer product can be isolated from the solvent and then dispersed in a suitable carrier oil for the emulsification process of the invention.

Alternatively, in some embodiments, the reaction may be conducted in situ using a carrier oil as the solvent. In a particular embodiment, the copolymer is synthesised directly within a carrier oil which forms the oil phase in the emulsion.

Typically, the term "carrier oil" is used herein to refer to an organic or "oil" phase having a boiling point of greater than 80 °C. Typically, the carrier oil will have a boiling point of greater than 100°C, more typically greater than 120°C and most typically greater than 130°C. Such carrier oils are generally considered to be nonvolatile liquids at ambient temperature and pressure. The elevated boiling points of the carrier oils enable the polymerisation reaction to proceed at an elevated temperature, which can significantly reduce the polymerisation reaction time. Any suitable carrier oil could be used. The carrier oil is preferably the same carrier oil that will be used as the dispersed or bulk phase in the subsequent emulsion process, i.e. the copolymer is synthesised directly within the carrier oil that will form the dispersed or bulk phase of the emulsion. In such cases, there is no need to isolate and further purify the copolymer. Typically, the carrier will be used to form the dispersed phase in an oil-in-water emulsion.

In addition to being a solvent for the polymerisation reaction to form the copolymer, the carrier oil may also be a solvent for a benefit agent or a vehicle in which a benefit agent is dispersed. Alternatively, the carrier oil might be a benefit agent itself. Examples of suitable carrier oils include common organic solvents such as aromatic compounds such as toluene, xylene, naptha, linear or branched hydrocarbons of different chain lengths and viscosities such as mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecane, squalane, hydrogenated polyisobutylene, polybutene, polydecene, docosane, hexadecane, isohexadecane and other isoparaffins, which are branched hydrocarbons, ketones such as cyclohexanone, silicones such as polyalkylsiloxanes, polydialkylsiloxanes, polydiarylsiloxanes, and polyalkarylsiloxanes may also be used. This includes the polydimethylsiloxanes, which are commonly known as dimethicones. Further cyclic siloxanes (e.g., cyclopentasiloxane) and dimethiconoles, alkyl methicones, alkyl dimethicones, dimethicone copolyols, aminofunctional silicones (e.g. amodimethicone, trimethylsilyloxyamodimethicone) and amphoteric silicones (e.g., cetyl PEG/PPG- 5/1 butyl ether dimethicone, and bis-PEG- 18 methyl ether dimethyl silane). Alcohol, diol, triol or polyol esters of carboxylic or dicarboxylic acids, of either natural or synthetic origin having straight chain, branched chain and aryl carboxylic acids include diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, cetyl lactate, myristyl lacate, lauryl lactate, C 12 - 15 lactate, dioctyl malate, decyl oleate, isodecyl oleate, ethylene glycol distearate, ethylhexyl palmitate (octyl palmitate), isodecyl neopentanoate, tridecyl neopentanoate, castoryl maleate, isostearyl neopentanoate, di- 2- ethylhexyl maleate, cetyl palmitate, myristyl myristate, stearyl stearate, cetyl stearate, isocetyl stearate, dioctyl maleate, octyl dodecyl stearate, isocetyl stearoyl stearate, octyldodecyl stearoyl stearate dioctyl sebacate, diisopropyl adipate, cetyl octanoate, glyceryl dilaurate, diisopropyl dilinoleate and caprylic/capric triglyceride. Naturally occurring includes triglycerides, diglycerides, monoglycerides, long chain medium chain and short chain wax esters and blends of these. Examples for naturally derived ester-based oils and waxes include, but are not limited to, moringa pterygoserma seed extract, argan oil, corn oil, castor oil, coconut oil, cottonseed oil, menhaden oil, avocado oil, beeswax, carnauba wax, cocoa butter, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, rice bran oil, pine oil, sesame oil, sunflower seed oil and safflower oil. Also useful are hydrogenated, ethoxylated, propoxylated and maleated derivatives of these materials, e.g. hydrogenated safflower oil, hydrogenated castor oil and medium chain triglycerides.

Preferred carrier oils include^ mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecan, docosane, hexadecane, ketones such as cyclohexanone, poly(dimethyl siloxanes), diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, ethylhexyl palmitate (octyl palmitate), palmitate, myristyl myristate, stearyl stearate, diisopropyl adipate, and caprylic/capric triglyceride. Corn oil, castor oil, coconut oil, cottonseed oil, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, pine oil, sesame oil, sunflower seed oil and safflower oil and medium chain triglycerides.

The chain transfer agent (CTA) and initiator

The chain transfer agent (CTA) is a molecule which is known to reduce molecular weight during a free-radical polymerisation via a chain transfer mechanism. These agents may be any thiol-containing molecule and can be either monofunctional or multifunctional. The agent may be hydrophilic, hydrophobic, amphiphilic, anionic, cationic, neutral, zwitterionic or responsive. The agent can also be an oligomer or a pre-formed polymer containing a thiol moiety. The agent may also be a hindered alcohol or similar free-radical stabiliser such as 2, 4-diphenyl-4-methyl-1 -pentene. Catalytic chain transfer agents, such as those based on transition metal complexes, e.g. cobalt bis(borondifluorodimethyl-glyoximate) (CoBF) may also be used. Suitable thiols include but are not limited to C2-C18 alkyl thiols such as dodecane thiol, thioglycolic acid, thioglycerol, cysteine and cysteamine. Thiol-containing oligomers or polymers may also be used, such as poly(cysteine) or an oligomer or polymer which has been post-functionalised to give a thiol group(s), such as poly(ethyleneglycol) (di)thio glycollate, or a pre-formed polymer functionalised with a thiol group, for example, reaction of an end or side-functionalised alcohol such as polypropylene glycol) with thiobutyrolactone, to give the corresponding thiol-functionalised chain- extended polymer. Multifunctional thiols may also be prepared by the reduction of a xanthate, dithioester or trithiocarbonate end-functionalised polymer prepared via a Reversible Addition Fragmentation Transfer (RAFT) or Macromolecular Design by the Interchange of Xanthates (MADIX) living radical method. Xanthates, dithioesters, and dithiocarbonates may also be used, such as cumyl phenyldithioacetate. Alternative chain transfer agents may be any species known to limit the molecular weight in a free-radical addition polymerisation including alkyl halides and transition metal salts or complexes. More than one chain transfer agent may be used in combination. When the chain transfer agent is providing the necessary hydrophilicity in the copolymer, it is preferred that the chain transfer agent is hydrophilic and has a molecular weight of at least 1 ,000 Daltons.

Where the polymer is comprised of primarily hydrophilic monomers and branchers it is preferred that the CTA is a hydrophobic compound. Hydrophobic CTAs include but are not limited to linear and branched alkyl and aryl (di)thiols such as dodecanethiol, octadecyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3- mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9- nonanedithiol and 2,4-diphenyl-4-methyl-1 -pentene. Hydrophobic macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from hydrophobic polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed hydrophobic polymer can be post functionalised with a compound such as thiobutyrolactone.

Hydrophilic CTAs typically contain hydrogen bonding and/or permanent or transient charges. Hydrophilic CTAs include but are not limited to thio-acids such as thioglycolic acid and cysteine, thioamines such as cysteamine and thio-alcohols such as 2-mercaptoethanol, 3-mercaptopropanoic acid, thioglycerol and ethylene glycol mono- (and di-)thio glycollate. Hydrophilic macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from hydrophilic polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed hydrophilic polymer can be post functionalised with a compound such as thiobutyrolactone.

Responsive macro-CTAs (where the molecular weight of the CTA is at least 1 ,000 Daltons) can be prepared from responsive polymers synthesised by RAFT (or MADIX) followed by reduction of the chain end, or alternatively the terminal hydroxyl group of a preformed responsive polymer, such as polypropylene glycol), can be post functionalised with a compound such as thiobutyrolactone.

The residue of the chain transfer agent may comprise 0 to 80 mole %, preferably 0 to 50 mole %, more preferably 0 to 40 mole % and especially 0.05 to 30 mole %, of the copolymer (based on the number of moles of monounsaturated monomer).

The initiator is a free-radical initiator and can be any molecule known to initiate free- radical polymerisation such as azo-containing molecules, persulfates, redox initiators, peroxides, phenyl benzyl ketones. These may be activated via thermal, photolytic or chemical means. Examples of these include but are not limited to azo- compounds e.g. 2,2'-azobisisobutyronitrile (AIBN), azobis(4-cyanovaleric acid) or peroxides such as benzoyl peroxide, and the Luperox® range from Arkema such as di-t-butyl peroxide (Luperox® Dl), t-butyl peroxybenzoate, (Luperox® P), dicumylperoxide (Luperox® DCP), di-t-amyl peroxide (Luperox® DTA), 1 - hydroxycyclohexyl phenyl ketone, hydrogenperoxide/ascorbic acid. Iniferters such as benzyl-N,N-diethyldithiocarbamate can also be used. In some cases, more than one initiator may be used. The initiator may be a macroinitiator having a molecular weight of at least 1 ,000 Daltons. In this case, the macroinitiator may be hydrophilic, hydrophobic, or responsive.

Preferably, the residue of the initiator in a free-radical polymerisation comprises 0 to 40% w/w, preferably 0.01 to 30% w/w and especially 0.01 to 20 w/w, of the copolymer based on the total weight of the monomers.

The use of a chain transfer agent and an initiator is preferred. However, some molecules can perform both functions.

Hydrophilic macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from hydrophilic polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use in Atom Transfer Radical Polymerisation (ATRP) with a suitable low valency transition metal catalyst, such as CuBr Bipyridyl.

Hydrophobic macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from hydrophobic polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use with ATRP.

Responsive macroinitiators (where the molecular weight of the preformed polymer is at least 1 ,000 Daltons) can be prepared from responsive polymers synthesised by RAFT (or MADIX), or the terminal hydroxyl group of a preformed hydrophilic polymer can be post-functionalised with a compound such as 2-bromoisobutyryl bromide for use with ATRP.

Preferred chain transfer agents include: dodecanethiol, octadecyl mercaptan, 2- ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3-mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9-nonanedithiol and 2,4-diphenyl-4- methyl-1 -pentene.

Preferred initiators include: 2,2'-azobisisobutyronitrile (AIBN), azobis(4-cyanovaleric acid), and compounds from the Luperox® range from Arkema such as benzoyl peroxide, di-t-butyl peroxide (Luperox® Dl), t-butyl peroxybenzoate, (Luperox® P), dicumylperoxide (Luperox® DCP), di-t-amyl peroxide (Luperox® DTA), 1 - hydroxycyclohexyl phenyl ketone and hydrogenperoxide/ascorbic acid.

Reaction conditions for the addition polymerisation

The addition polymerisation suitably process proceeds via a solution polymerisation wherein the reactants, monomer(s), brancher(s), chain transfer agent(s) and initiator(s), are added to a solvent (e.g. an organic solvent suitable for solution polymerisation or a carrier oil as defined herein) and polymerisation proceeds through initiation. It is preferred that the reactants are soluble in the solvent (e.g. methanol, ethanol or a carrier oil) at the reaction temperature although they can also be dispersed in the solvent, likewise it is preferred that the addition copolymer product is also soluble in the solvent at the reaction temperature although the addition copolymer product can also be dispersed within the solvent following polymerisation. The solids content of the polymerisation process can be from 0.5 % to 90 % w/w, preferably between 5 % and 80 % w/w and especially between 10 and 70 % w/w.

The polymerisation can proceed via a batch process wherein all of the components are added to the reaction vessel at the start of the polymerisation process and the addition copolymer product isolated in the solvent (e.g. an organic solvent suitable for solution polymerisation or a carrier oil as defined herein) following reaction. The polymerisation can also take place via a feed process whereby the reactants are added continuously throughout the polymerisation process from one or more separate source vessels, this can be done in such a way that the monomers are consumed uniformly during the polymerisation process to avoid monomer build-up, so-called accumulation. Additionally it is preferred in this case that the initiator is added separately in order to cease the reaction by stopping the initiator feed, if required, this process is known in the art as a starved-feed polymerisation and is common in solution or emulsion polymerisation processes. In this case the reactants can be added neat to the solvent or more preferably added as solutions or dispersions within the solvent.

This process can also be performed where a portion of the reaction solution is added to the vessel at the start of the process, typically around 20 to 30 % and the remaining constituents are added throughout the process, so-called semi-batch process. Following the addition of the reactants the polymerisation can be allowed to proceed for a period of time, in some instances an additional aliquot of initiator can be added to consume any free monomer that may be present.

The initiation of the polymerisation can occur through thermal means or via electromagnetic radiation such as ultra violet light or gamma rays, such as from a Co-60 source, or through chemical means such as a REDOX reaction with an oxidant or reducing agent and an appropriate initiator. The reaction can also proceed in a flow or tubular reactor where the reactants are passed through a tubular vessel with a designated polymerisation zone, usually a heated section with a temperature gradient, and the reactants are obtained after a set residence time. In this process the polymerisation solution can also be re-circulated until the appropriate degree of polymerisation is obtained. In a batch, fed or semi-batch process the reaction vessel can be glass, mild steel, stainless steel, glass-lined or Hastelloy in construction and fitted with appropriate heating sources such as an oil or steam-heated jacket and cooling such as a condenser or cooling coils externally or internally fitted on or in the vessel. Where necessary the reactants can be dosed into the vessel manually or via gravity or metered pumps. It is preferred that the reaction proceeds at atmospheric pressure although higher pressures can be used with lower boiling point reactants or carrier oils.

It is preferred that the polymerisation reaction occurs at a temperature of 60 to 180 °C. The reaction time can be between 3 hours to 48 hours, preferably 5 to 24 hours.

The process described above provides the copolymer in a solvent. If the solvent is not a carrier oil, then the polymer can be isolated from the reaction solvent, optionally purified using conventional techniques known in the art and dispersed within a carrier oil phase for the subsequent emulsification process of the invention.

In embodiment where the solvent used for the polymerisation reaction is a carrier oil, then the resultant carrier oil / copolymer composition can then be used directly in the emulsification process, as defined further herein.

The present invention also provides a polymer capsule obtainable by, obtained by, directly obtained by, or formed by, a process as defined in the tenth aspect of the invention.

Particular embodiments

The following numbered paragraphs 1 ) to 47) are not claims, but instead describe particular embodiments of aspects 10 and 1 1 of the invention:

1 ) A method of preparing a crosslinked polymeric capsule, the process comprising: providing a mixture comprising an oil phase, an aqueous phase, a statistical branched amphiphilic copolymer having one or more functional groups and a crosslinking agent having two or more functional groups capable of reacting with the functional groups present on the statistical branched amphiphilic copolymer to form crosslinks between adjacent copolymer molecules; emulsifying the mixture to form an emulsion; and allowing the crosslinking agent to react with the functional groups on the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the oil phase and the aqueous phase; wherein the statistical branched amphiphilic copolymer comprises at least two polymeric chains which are covalently linked by a bridge; and wherein the at least two chains are formed by the polymerisation of one or more ethylenically monounsaturated monomers and the bridge is formed by the polymerisation of at least one ethylenically polyunsaturated monomer; and wherein the copolymer comprises one or more functional groups capable of reacting with functional groups present on the crosslinking agent.

2) A method according to numbered paragraph 1 , wherein the emulsion is an oil- in-water emulsion.

3) A method according to numbered paragraph 1 , wherein the emulsion is a water-in-oil emulsion.

4) A method according to any one of the preceding numbered paragraphs, wherein the statistical branched amphiphilic copolymer comprises at least two polymeric chains which are covalently linked by a bridge other than at their ends.

5) A method according to any one of the preceding numbered paragraphs, wherein the statistical branched amphiphilic copolymer comprises the residue of a chain transfer agent and/or an initiator; and at least one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophilic residue, and at least one of one of the monounsaturated monomer(s) and/or polyunsaturated monomer(s) and/or chain transfer agent is a hydrophobic residue.

6) A method according to any one of the preceding numbered paragraphs, wherein the molar ratio of polyunsaturated monomer(s) to monounsaturated monomer(s) in the statistical branched amphiphilic copolymer is from 1 :100 to 1 :4.

7) A method according to any one of the preceding numbered paragraphs, wherein the molar ratio of the ethylenically polyunsaturated monomer component to the ethylenically monounsatu rated monomer component of the copolymer is 1 :50 to 1 :4.

8) A method according to any one of the preceding numbered paragraphs, wherein the molar ratio of the ethylenically polyunsaturated monomer component to the ethylenically monounsatu rated monomer component of the copolymer is 1 :20 to 1 :4.

9) A method according to any one of the preceding numbered paragraphs, wherein the copolymer is formed by an addition polymerisation process, which comprises mixing together:

(a) the one or more ethylenically monounsaturated monomers;

(b) the one or more ethylenically polyunsaturated monomers;

(c) a chain transfer agent; and

(d) an initiator; in a solvent and reacting the mixture to form the statistical branched amphiphilic copolymer.

10) A method according to numbered paragraph 9, wherein from the amount of polyunsaturated monomer is 1 to 25 mole% (based on the number of moles of monounsaturated monomer(s)).

1 1 ) A method according to any one of the preceding numbered paragraphs, wherein the statistical branched amphiphilic copolymer comprises a functional group capable of reacting with a functional group present on the crosslinking agent by a reaction selected from the group consisting of nucleophilic substitution, electrophilic addition, ring-opening reactions, sol-gel reactions (such as the reaction between di- tri-or poly alkoxy silanes), Diels-Alder reactions, ester formation, amide formation, urethane formation, urea formation, carbonate formation, thiol-ene formation, addition polymerisation, and the 1 + 3 Huisgen cycloaddition reaction (so-called "click chemistry").

12) A method according to any one the preceding numbered paragraphs, wherein the statistical branched amphiphilic copolymer comprises one or more functional groups selected from the group consisting of amines, alcohols, thiols, ketones, carboxylic acids, acid chlorides, halogens, alkoxysilanes, epoxides, and acetoacetates.

13) A method according to any one the preceding numbered paragraphs, wherein the statistical branched amphiphilic copolymer comprises one or more pendant alkoxysilane functional groups.

14) A method according to numbered paragraph 13, wherein the pendent alkoxysilane groups are pendant mono-, di- or tri-(1 -2C)alkoxysilane functional groups.

15) A method according to numbered paragraph 13 or 14, wherein the alkoxysilane groups are present on an ethylenically monounsatu rated monomer component.

16) A method according to numbered paragraph 15, wherein the polymer comprises one or more ethylenically monounsatu rated monomers of Formula (1 ):

H ₂ C=CH(Ri)-C(O)-O-R2-Si(OR3)3

Formula (1 ) wherein Ri is H or an optionally substituted (1 -4C)alkyl group; R2 is a (2- 8C)alkylene group and R3 is an optionally substituted (1 -4C)alkyl group.

17) A method according to numbered paragraph 16, wherein in the ethylenically monounsaturated crosslinking monomer of formula I, Ri is H or (1 -2C)alkyl; R2 is a (2-4C)alkylene; and R3 is (1 -3C)alkyl.

18) A method according to any one of numbered paragraphs 16 or 17, wherein in the ethylenically monounsaturated crosslinking monomer of formula I, Ri is H or methyl; R2 is ethylene or propylene; and R3 is (1 -2C)alkyl.

19) A method according any one of numbered paragraphs 16 to 18, wherein the crosslinking monomer of formula I is selected from trimethoxysilylpropylacrylate, triethoxysilylpropylacrylate, trimethoxysilylpropylmethacrylate and

triethoxysilylpropylmethacrylate.

20) A method according to any one of numbered paragraphs 16 to 19, wherein the crosslinking monomer of formula I accounts for 10 to 100 mole% of the ethylenically monounsaturated monomer component of the copolymer. 21 ) A method according to numbered paragraph 20, wherein the crosslinking monomer of formula I accounts for 60 to 100 mole% of the ethylenically monounsaturated monomer component of the copolymer.

22) A method according to any one of numbered paragraphs 16 to 21 , wherein the polymer further comprises one or more additional ethylenically monounsaturated monomers in addition to the crosslinking monomer of formula I.

23) A method according to numbered paragraph 22, wherein the one or more additional ethylenically monounsaturated monomers account for 0 to 90 mole% of the ethylenically monounsaturated monomer component of the copolymer.

24) A method according to numbered paragraph 23, wherein the one or more additional ethylenically monounsaturated monomers account for 0 to 40 mole% of the ethylenically monounsaturated monomer component of the copolymer.

25) A method according to any one of the preceding numbered paragraphs, wherein the ethylenically polyunsaturated monomer is selected from the group consisting of divinyl benzene, ethyleneglycol di(meth)acrylate, 1 ,4 butanediol di(methacrylate), hexane diol di(meth)acrylate, poly(ethyleneglycol) di(meth)acrylate and N, N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and dipentaerithritol hexa(meth)acrylate.

26) A method according to any one of numbered paragraphs 5 to 25, wherein the chain transfer agent (CTA) is a hydrophobic compound.

27) A method according to numbered paragraph 26, wherein the hydrophobic CTA is selected from linear and branched alkyl and aryl (di)thiols (e.g. dodecanethiol, octadecyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-1 -butanethiol, butyl 3- mercaptopropionate, i-octyl 3-mercaptopropionate, t-dodecyl mercaptan, 1 ,9- nonanedithiol and 2,4-diphenyl-4-methyl-1 -pentene).

28) A method according to any one of numbered paragraphs 5 to 25, wherein the chain transfer agent (CTA) is a hydrophilic compound.

29) A method according to numbered paragraph 28, wherein the hydrophilic CTA is selected from thio-acids (e.g. thioglycolic acid and cysteine), thioamines (e.g. cysteamine) and thio-alcohols (e.g. 2-mercaptoethanol, 3-mercaptopropanoic acid, thioglycerol and ethylene glycol mono- (and di-)thio glycollate). 30) A method according to any one of numbered paragraphs 9 to 29, wherein the chain transfer agent (CTA) is present at 0 to 80 mole % (based on the number of moles of monounsaturated monomer).

31 ) A method according to numbered paragraph 30, wherein the chain transfer agent (CTA) is present at 0 to 50 mole % (based on the number of moles of monounsaturated monomer).

32) A method according to any one of numbered paragraphs 9 to 31 , wherein the initiator is a free-radical initiator.

33) A method according to any one of numbered paragraphs 9 to 31 , wherein the initiator is present in an amount of 0.01 to 40% w/w.

34) A method according to any one of numbered paragraphs 9 to 33, wherein the solvent is a carrier oil.

35) A method according to any one of the preceding numbered paragraphs, wherein oil phase is a carrier oil and the concentration of the statistical branched amphiphilic copolymer in the carrier oil is 0.5 % to 90 % w/w.

36) A method according to any one of the preceding numbered paragraphs, wherein the carrier oil has a boiling point above 100 °C.

37) A method according to any one of the preceding numbered paragraphs, wherein the carrier oil is selected from the group consisting of mineral oil, petrolatum, white oil (also known as paraffin oil), dodecane, hexadecane, isododecan, docosane, hexadecane, ketones such as cyclohexanone, poly(dimethyl siloxanes), diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, myristyl propionate, ethylhexyl palmitate (octyl palmitate), palmitate, myristyl myristate, stearyl stearate, diisopropyl adipate, and caprylic/capric triglyceride. Corn oil, castor oil, coconut oil, cottonseed oil, palm kernel oil, palm oil, peanut oil, shea butter, jojoba oil, soybean oil, rapeseed oil, linseed oil, pine oil, sesame oil, sunflower seed oil, safflower oil and medium chain triglycerides.

38) A method according to any one of the preceding numbered paragraphs, wherein the oil phase or the aqueous phase is, or comprises, a benefit agent.

39) A method according to numbered paragraph 38, wherein the emulsion is an oil- in-water emulsion and the oil phase comprises a benefit agent. 40) A method according to any one of the preceding numbered paragraphs, wherein the crosslinking agent comprises a functional group capable of reacting with a functional group present on the copolymer by a reaction selected from the group consisting of nucleophilic substitution, electrophilic addition, ring-opening reactions, sol-gel reactions (such as the reaction between di-tri-or poly alkoxy silanes), Diels- Alder reactions, ester formation, amide formation, urethane formation, urea formation, carbonate formation, thiol-ene formation, addition polymerisation, and the 1 + 3 Huisgen cycloaddition reaction (so-called "click chemistry").

41 ) A method according to any one of the preceding numbered paragraphs, wherein crosslinking agent comprises one or more alkoxy silanes moieties.

42) A method according to any one of the preceding numbered paragraphs, wherein crosslinking agent is selected from tetramethyl orthosilicate and tetraethyl orthosilicate, sodium silicate, bis(triethoxysilyl)ethane, bis(trimethoxyethyl)silane, tris- [3-(trimethoxysilyl)propyl]isocyanurate, tris-[3-(triethoxysilyl)propyl]isocyanurate, mercapropropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-octanoylthio-1 - propyl triethoxysilane, aminopropyl trialkoxysilanes such as aminopropyltrimethoxy silane or aminopropyl triethoxysilane, aminopropyl methyl diethoxysilane, Ν-(β- aminoethyl)-Y-aminopropyl trimethoxysilane, N-[N'-(2-aminoethyl)aminoethyl]-3- aminopropyl trimethoxysilane, N-phenyl aminopropyl trimethoxysilane, N-ethyl- aminoisobutyl trimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, ureidopropyl trimethoxysilane, isocyanatopropyl triethoxysilane, isocyanatopropyl trimethoxysilane, glycidoxypropyl trimethoxysilane, glycidoxypropyl triethoxysilane, 3,4 - epoxycyclohexyl - ethyl trimethoxysilane and 3,4 - epoxycyclohexyl - ethyl triethoxysilane.

43) A method according to any one of the preceding numbered paragraphs, wherein the step of allowing the crosslinking agent to react with the functional groups on the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the oil phase and the aqueous phase involves allowing the emulsion to stand for a period of 1 to 48 hours and optionally adding a catalyst to promote the crosslinking reaction.

44) A method according to any one of the preceding numbered paragraphs, wherein the copolymer and crosslinking agent comprise functional alkoxysilane groups and the step of allowing the crosslinking agent to react with the functional groups on the statistical branched amphiphilic copolymer to form a covalently linked polymeric capsule shell at the interface between the oil phase and the aqueous phase involves allowing the emulsion to stand for a period of 1 to 48 hours and optionally adding an acid or a base to catalyse the reaction.

45) A polymer capsule obtainable by a process as defined in any one of numbered paragraphs 1 to 44.

46) A polymer capsule according to numbered paragraph 45, wherein the particle size of the capsule is less than 100 microns.

47) A polymer capsule according the numbered paragraph 45 or 46, wheren the capsule comprises a benefit agent.

EXAMPLES

The present invention will now be explained in more detail by reference to the following non-limiting examples.

In the following examples, copolymers are described using the following nomenclature:

(MonomerG)g (Monomer J)j (Brancher L)i (Chain Transfer Agent) d wherein the values in subscript are the molar ratios of each constituent normalised to give the monofunctional monomer values as 100, that is, g + j = 100. Linear poylmers do not contain a brancher and may or may not contain a chain transfer agent. The degree of branching or branching level is denoted by I and d refers to the molar ratio of the chain transfer agent.

For example:

Methacrylic acid-ioo Ethyleneglycol dimethacrylate-is Dodecane thiohs would describe a branched addition copolymer containing methacrylic acid : ethyleneglycol dimethacrylate : dodecane thiol at a molar ratio of 100:15:15. MATERIALS

Abbreviation Name Supplier

Monomers (ethylenicallv monounsatu rated monomers):

DEAMA diethylaminoethyl methacrylate Aldrich chemical Co

LMA lauryl acrylate Aldrich chemical Co

MAA methacrylic acid Aldrich chemical Co

PEG(1 K)A poly(ethyleneglycol) acrylate Aldrich chemical Co

(Average Mw 1 ,000 Da)

PEG(1 K)MA poly(ethyleneglycol) methacrylate Aldrich chemical Co

(Average Mw 1 ,000 Da)

BMA butyl methacrylate Aldrich chemical Co

TMSPMA trimethoxysilylpropyl methacrylate Aldrich chemical Co

HEMA ydroxyet yl methacrylate Aldrich chemical Co

Branchers (ethvlenicallv polyunsaturated monomers):

DVB divinyl benzene Aldrich chemical Co

EGDMA ethyleneglycol dimethacrylate Aldrich chemical Co

TEGDA tetraethyleneglycol diacrylate Aldrich chemical Co

Chain Transfer Aqents (CTAs):

DDT dodecanethiol Aldrich chemical Co

DMP 2,4-diphenyl-4-methyl-1 -pentene Aldrich chemical Co

Initiators:

AIBN azobisisobutyrylnitrile Aldrich chemical Co

Dl di-t-butyl peroxide Aldrich chemical Co t-butyl peroxybenzoate Aldrich chemical Co

Carrrier oils:

THF tetrahydrofuran Aldrich chemical Co

EtOH ethanol Aldrich chemical Co

MCT medium chain triglyceride Threw Arnott & Co

SuF sunflower oil Tescos

SaF safflower oil Aldrich chemical Co

Xy Xylene Aldrich chemical Co

Additional crosslinkers:

APTMS aminopropyl(trimethoxy)silane Aldrich chemical Co DAMO [3-(3-aminoethylamino) Aldrich chemical Co

-propyl]trimethoxy silane

NaSi sodium silicate Aldrich chemical Co

TEOS tetraethyl orthosilicate Aldrich chemical Co TRIAMO N'-(3-ttrimethoxysilylpropyl) Aldrich chemical Co

-diethylenetriamine

Active Compounds (benefit agents):

Ethylhexyl-4-methoxycinnamate Aldrich chemical Co

Eugenol Aldrich chemical Co

Geraniol Aldrich chemical Co

Ibuprofen Aldrich chemical Co

Isoamyl acetate Aldrich chemical Co Menthol Aldrich chemical Co

Methyl anthranilate Aldrich chemical Co

Vitamin E Aldrich chemical Co

Benzyl acetate Aldrich chemical Co

Limonene Aldrich chemical Co

Powdet Bit Aldrich chemical Co

Sortest Aldrich chemical Co

Yellow Sunshine Aldrich chemical Co

A model fragrance was prepared by combining equal volumes of geraniol, eugenol and methyl anthranilate.

POLYMER CHARACTERISATION Nuclear magnetic resonance (NMR)

All proton nuclear magnetic resonance ( ¹ H NMR) spectra were recorded using a Bruker Advance NMR spectrometer operating at 400 MHz.

Size exclusion chromatography (SEC)

SEC measurements were used to determine the molar mass, molar mass

distribution, absolute molecular weight and Mark-Houwink values of branched copolymers. A triple-detection Viscotek triple detection gel permeation

chromatography system (TD-GPC) with refractive index, viscometry and dual-angle light scattering detectors was used. One Viscotek LT5000L and one LT4000L columns and an additional guard column were used with an oven temperature of 30 °C. The eluent was THF with a flow rate of 1 imL min ^-1 . Samples were prepared at 2, 3 and 5 img/imL. EMULSION DROPLET AND CAPSULE CHARACTERISATION TECHNIQUES

Capsule size determination by light scattering

All capsule size distributions were assessed using laser diffraction with a Malvern Mastersizer 3000 equipped with a Hydro LV dispersion unit. For all capsule measurements, an approximate sample laser obscuration of 3% was obtained within the dispersion unit containing 80 mL water with a stirring rate of 1 ,800 rpm. The volume-average droplet diameters were obtained from at least 5 repeat runs. The span is a measure of the width of the droplet size distribution and is expressed mathematically as (D(0.9) - D(0.1 ))/D(0.5), where D(0.9) is the diameter under which 90 % of the particles fall, D(0.5) is the diameter under which 50 % of the particles fall and D(0.1 ) is the diameter under which 10 % of the particles fall.

Capsule surface charge determination

Zeta potential measurements of the capsule slurry were measured by electrophoretic light scattering in a Malvern Zetasizer Nano Z equipped with a He-Ne 633 nm laser. All samples were measured in a disposable polystyrene folded capillary cell cuvette.

EXAMPES OF ASPECTS 1 TO 7 OF THE INVENTION General polymer synthesis procedure:

The polymers were prepared via the following general procedure unless stated otherwise.

Example BP8, 20 g scale, 40% solids

A 250 mL flange-pot reactor equipped with a stirrer bar and a condenser was set up on a heat-on block hotplate system. A mixture of TMSPMA (13.72 g, 55.26 mmol), PEG(1 K)MA (2.76 g, 2.91 mmol), EGDMA (1 .73 g, 8.73 mmol) and DDT (1 .78 g, 8.73 mmol) and MCT (33.52 mL). The mixture was degassed by purging for 15 minutes with nitrogen before being heated up to 130 °C. Once this temperature was reached, Dl (0.33 g, 2.27 mmol) was added in equal aliquots at t=0, 30, 60, 90 mins and at 5 hours to the reactor. ^* The mixture was stirred with heating for a further 19 hours. The polymer solution was then cooled to ambient temperature and poured into a jar.

^* where AIBN was used as the initiator, ait was all added in one step at t=0.

Emulsion droplet and capsule preparation

General procedure 1 for high and low shear homogenisation methods Example EC13

A solution of polymer in carrier phase (polymer-in-MCT, 1 .560 mL) was prepared in a 28.25 mL glass vial. An extra amount of carrier phase (MCT, 1 .440 mL) was added to the vial. An equal volume of distilled water (3 mL) was added. This biphasic mixture was homogenised at 3,400 rpm for 2 minutes using a T25 digital Ultra Turrax. Following homogenisation, the emulsion was left to equilibrate overnight. Capsule formation occurred by the addition of base (NaOH, 1 M, 0.125 w/v% of the total volume) to the emulsion under vigorous stirring and left to stir for 1 hour before further characterisation.

General procedure 2 for membrane emulsification method Example EC30

A discontinuous phase of polymer (8 w/v% of the total volume) in oil (MCT) was prepared in a 10 mL syringe attached to a syringe pump. 2.5 mL of this discontinuous phase was passed through a 10 μιη membrane into a Micropore Cell Dispersion unit at a flow rate of 0.5 imL/min under shear (with the stirrer motor set at 12 V 0.16 A) into a continuous phase of distilled basic water (100 mL) at pH 9 (NaOH, 1 M). Following capsule formation, the capsule slurry was allowed to equilibrate overnight before characterisation. General procedure 3 for membrane emulsification method Example EC31

A discontinuous phase of polymer (8 w/v% of the total volume) in oil (MCT) was prepared in a 10 mL syringe attached to a syringe pump. 2.5 mL of this discontinuous phase was passed through a 10 μιη membrane into a Micropore Cell Dispersion unit at a flow rate of 0.5 imL/min under shear (with the stirrer motor set at 9 V) into a continuous phase of distilled basic water (100 mL). The emulsion was left to equilibrate overnight. Capsule formation occurred by the addition of base (NaOH, 1 M, 0.125 w/v% of the total volume) to the emulsion under vigorous stirring and left to stir for 1 hour before further characterisation.

where monomer "A" refers to the functionalised monofunctional monomer (e.g. TMSPMA) , "B" and "C" refer to the non-functional monofunctional monomers (e.g. PEGMA, PEGA, LA, MAA)

Emulsion / capsule formation examples and results:

example was formed in a 100 mL equipment chamber.

Determination of linear vs branched emulsion stability

In order to determine the intrinsic stability of emulsions prepared stabilised with a linear and branched amphiphilic copolymer emulsions were prepared using the branched copolymer BP8 and the linear comparator example LP2 using MCT as the internal phase using General Emulsification Route 1

Laser diffraction measurements were carried out using a Malvern Mastersizer 3000 with a Hydro LV cell. The samples were added to the Hydro LV cell which contains 500 mL of deionised water to an obscuration of 4-5%. The stirrer speed of the cell was set to 1800 rpm and the diameter of the emulsion droplets were measured every minute for 1 hour.

The data clearly shows the higher stability of the emulsions prepared using the branched polymer JW297094 compared to the linear equivalent polymer JW297013. In the case of the emulsions prepared with the linear equivalent polymer the emulsion droplet diameter decreases significantly over the one hour measurement period as shown by the laser diffraction analyses. This deviation over time would provide production issues as emulsions prepared using linear polymers would destabilise over time and as such the "locking-in" stage of cross-linking to form encapsulates would give rise to different encapsulate sizes due to the changes in emulsion droplet sizes. In comparison, emulsions prepared using branched polymers have a higher inherent stability due to the amphiphilic copolymer's architecture. As such, these stable droplets can then be cross-linked within longer time periods to form capsules where the size is consistent with the size of the formed emulsions.

EXAMPLES OF ASPECTS 8 AND 9 OF THE INVENTION General polymer synthesis procedure:

The polymers listed in Table 1 were prepared via the following general procedure unless stated otherwise.

Example BP5, 20 g scale, 40% solids

A 250 mL flange-pot reactor equipped with a stirrer bar and a condenser was set up on a heat-on block hotplate system. A mixture of TMSPMA (13.72 g, 55.26 mmol), PEG(1 K)MA (2.76 g, 2.91 mmol), EGDMA (1 .73 g, 8.73 mmol) and DDT (1 .78 g, 8.73 mmol) and MCT (33.52 mL). The mixture was degassed by purging for 15 minutes with nitrogen before being heated up to 130 °C. Once this temperature was reached, Dl (0.33 g, 2.27 mmol) was added in equal aliquots at t=0, 30, 60, 90 mins and at 5 hours to the reactor. ^* The mixture was stirred with heating for a further 19 hours. The polymer solution was then cooled to ambient temperature and poured into a jar.

Table 1 - list of polymers prepared:

where monomer "A" refers to the functionalised monofunctional monomer (e.g. TMSPMA) , "B" and "C" refer to the non-functional monofunctional monomers (e.g.

PEG(1 K)MA, PEGMA, PEGA, LA, MAA)

Interfacial encapsulation process

Examples EC1 to EC28 in Table 2 below were prepared by the following general procedure:

Example EC1

The model Fragrance (30 g) was mixed with MCT (9.1 g), polymeric isocyanate PAPI (3 g) and branched copolymeric emulsifier JW/29747 (1 .33 g), to prepare the oil phase. A solution of 1 % PVOH (Poval 3-85) was prepared by adding PVOH (0.6 g) deionised water (60 g) with stirring at room temperature. The oil phase was emulsified into the water phase using a high shear homogeniser, Ultraturrax, for two minutes at 6,600 rpm. The formed emulsion was then placed in a round bottom flask and an aqueous solution of HMDA (4.1 g) was added under constant stirring using an overhead stirrer. After addition the stirring speed was reduced. The capsule slurry was then heated with stirring for 3 hours at 55 °C. After the curing, the capsules were washed with equal amount of Dl until the slurry was neutralised to pH 7.

Table 2 - Examples EC1 to EC28

Branched Additional

Active Weight of Weight

copolymer Isocyanate co- Amine added

Example compound additional of Water

Emulsifier (g) emulsifier (g, mmols)

(g) MCT/g added/g

(g) (g)

HMDA/DAMO

Isoamyl BP3 Poval 3-

EC16 PAPI (3.0) 9.1 60 (3.28/1.87, acetate (30) (1 .33) 85 (0.6)

0.01 13/0.0028)

HMDA/TRIAMO

Isoamyl BP3 Poval 3-

EC17 PAPI (3.0) 9.1 60 (3.28/1.57, acetate (30) 1 .33) 85 (0.6)

0.01 13/0.0028)

Isophorone

Revo model BP3 Poval 3- HMDA (3.78,

EC18 diisocyanate 9.1 60

(30) (1 .33) 85 (0.6) 0.01 13)

(3.0)

Isophorone HMDA/DAMO

Revo model BP3 Poval 3-

EC19 diisocyanate 9.1 60 (3.02/1.45, (30) (1 .33) 85 (0.6)

(3.0) 0.010/0.0026)

Isophorone HMDA/TRIAMO

Revo model BP3 Poval 3-

EC20 diisocyanate 9.1 60 (3.02/1.73,

(30) (1 .33) 85 (0.6)

(3.0) 0.010/0.0026)

Softest

BP4 Poval 3- HMDA

EC21 (Carvansons) PAPI (3.0) 9.1 60

(1 .33) 85 (0.6) (4.1 , 0.0141 ) (30)

BP4

EC22 Powdet Bit PAPI (3.0) Poval 3- HMDA

(1 .33) 9.1 60

(30) 85 (0.6) (4.1 , 0.0141 )

Yellow BP4 Poval 3- HMDA

EC23 PAPI (3.0) 9.1 60

sunshine(30) (1 .33) 85 (0.6) (4.1 , 0.0141 )

Softest Isophorone

BP4 Poval 3- HMDA (3.78,

EC24 (Carvansons) diisocyanate 9.1 60

(1 .33) 85 (0.6) 0.01 13) (30) (3.0)

Isophorone

Powdet Bit BP4 Poval 3- HMDA (3.78,

EC25 diisocyanate 9.1 60

(30) (1 .33) 85 (0.6) 0.01 13)

(3.0)

Yellow Isophorone

BP4 Poval 3- HMDA (3.78,

EC26 sunshine diisocyanate 9.1 60

(1 .33) 85 (0.6) 0.01 13) (30) (3.0)

Yellow Isophorone

BP4 Poval 3- HMDA (3.78,

EC27 sunshine diisocyanate 9.1 60

(1 .33) 85 (0.6) 0.01 13) (30) (1 .5)

Isoamyl BP4 HMDA

EC28 PAPI (3.0) 9.1 60 BP6 (0.6)

acetate (30) (1 .33) (4.1 , 0.0141 ) Table 3 - characterisation of polymeric capsules

Determination of linear vs. branched emulsion stability

In order to determine the intrinsic stability of emulsions prepared stabilised with a linear and branched amphiphilic copolymer emulsions were prepared using the branched copolymer BP5 and the linear example LP2 using MCT as the internal phase using General Emulsification Route 1

Laser diffraction measurements were carried out using a Malvern Mastersizer 3000 with a Hydro LV cell. The samples were added to the Hydro LV cell which contains 500 mL of deionised water to an obscuration of 4-5%. The stirrer speed of the cell was set to 1800 rpm and the diameter of the emulsion droplets were measured every minute for 1 hour. Branched polymer BP5

Linear polymer LP2

TMSPMA/PEGMA-EGDMA-DDT

Time / TMSPMA/PEGMA-DDT (95/5/2)

(95/5/1 5/1 5)

mins

Difference from Difference from

Droplet size / μιτι Droplet size / μιτι

t=0 / μιη t=0 / μιη

0 48.0 0.0 57.1 0.0

10 47.8 0.2 54.4 2.7

20 47.9 0.1 48.7 8.4

30 47.4 0.6 48.8 8.3

40 47.0 1 .0 46.0 1 1 .1

50 46.6 1 .4 45.2 1 1 .9

60 46.3 1 .7 45.2 1 1 .9

The data clearly shows the higher stability of the emulsions prepared using the branched polymer BP5 compared to the linear equivalent polymer LP2. In the case of the emulsions prepared with the linear equivalent polymer the emulsion droplet diameter decreases significantly over the one hour measurement period as shown by the laser diffraction analyses. This deviation over time would provide production issues as emulsions prepared using linear polymers would destabilise over time and as such the "locking-in" stage of crosslinking to form encapsulates would give rise to different encapsulate sizes due to the changes in emulsion droplet sizes. In comparison, emulsions prepared using branched polymers have a higher inherent stability due to the amphiphilic copolymer's architecture. As such, these stable droplets can then be crosslinked within longer time periods to form capsules where the size is consistent with the size of the formed emulsions.

EXAMPLES OF ASPECTS 10 AND 1 1 OF THE INVENTION

General polymer synthesis procedure:

The polymers shown in Table 4 were prepared via the following general procedure unless stated otherwise. Example BP2, 20 g scale, 40% solids

A 250 mL flange-pot reactor equipped with a stirrer bar and a condenser was set up on a heat-on block hotplate system. A mixture of TMSPMA (13.74 g, 55.32 mmol), PEG(1 K)MA (2.77 g, 2.91 mmol), EGDMA (1 .73 g, 8.74 mmol) and DDT (1 .76 g, 8.74 mmol) and MCT (33.52 mL). The mixture was degassed by purging for 15 minutes with nitrogen before being heated up to 130 °C. Once this temperature was reached, Dl (0.33 g, 2.27 mmol) was added in equal aliquots at t=0, 30, 60, 90 mins and at 5 hours to the reactor. ^* The mixture was stirred with heating for a further 19 hours. The polymer solution was then cooled to ambient temperature and poured into a jar.

Table 4 - am hi hilic co ol mer re aration and anal sis:

where monomer "A" refers to the functionalised monofunctional monomer (e.g. TMSPMA) , "B" and "C" refer to the non-functional monofunctional monomers (e.g. PEG(1 K)MA, PEGMA, PEGA, LA, MAA, HEMA)

Emulsion droplet and capsule preparation Method 1 for high shear homogenisation methods

Example EC 17

A solution of polymer in carrier phase (polymer-in-MCT, 1 .56 mL) was added to a 28.25 mL glass vial. The additional crosslinking agent, 3- aminopropyl)trimethoxysilane (APTMS) (0.15 mL), was also added to the carrier phase. A further quantity of carrier phase (MCT, 1 .29 mL) was added to the vial and mixed to form an isotropic solution. An equal volume of distilled water (3.00 mL) was added. This biphasic mixture was homogenised at 12,000 rpm for 2 minutes using a T25 digital Ultra Turrax. Following homogenisation, the emulsion was left to equilibrate overnight before further characterisation.

Method 2 for high shear homogenisation methods

Example EC5

A solution of polymer in carrier phase (polymer-in-MCT, 20.0 mL) was added to a 100 mL cylindrical steel flask. The additional crosslinking agent,3- aminopropyl)trimethoxysilane (APTMS) (2.5 mL), was also added to the carrier phase. A benefit agent, in this case the model fragrance (15.0 mL), was also added to the carrier phase. A further quantity of carrier phase (MCT, 12.5 mL) was added to the vial. An equal volume of distilled water (50.0 mL) was then added. This biphasic mixture was homogenised at 1 ,650 rpm for 10 minutes using a Silverson L5 Series Laboratory Mixer. Following homogenisation, the emulsion was left to equilibrate overnight before further characterisation.

Method 3 for low shear homogenisation methods

Example EC7

A solution of polymer in carrier phase (polymer-in-MCT, 20.0 mL) was added to a 100 mL cylindrical steel flask. The additional crosslinking agent, (3- aminopropyl)trimethoxysilane (APTMS) (2.5 mL), was also added to the carrier phase. A benefit agent, in this case model fragrance(15.0 mL), was also added to the carrier phase. A further quantity of carrier phase (MCT, 12.5 mL) was added to the vial. An equal volume of distilled water (50.0 mL) was added. This biphasic mixture was homogenised at 1 ,650 rpm for 10 minutes using a single four blade impeller attached to an overhead stirrer. Following homogenisation, the emulsion was left to equilibrate overnight before further characterisation.

Table 5 - polymer capsule examples formed by Methods 1 , 2 or 3 above

Solids Volume

Type Volume Amoun Volum

in Volume of of extra Ze

Example Polymer Carrier of shell of shell Benefit t of e of Metho Speed Time D10 D50 D90 D4/3 Spa carrier carrier carrier po ID ID phase additiv additive agent benefit water / d / rpm / min pm pm Mm Mm n

phase / phase / mL phase / / e / mL agent mL

%w/w mL

2- ethylhexyl

EC40 BP8 MCT 40 1.20 DAMO 0.15 0.75 -4- 0.90 mL 3.00 3,400 19.47 50.50 89.70 52.90 1.39 5 methoxyci

nnamate

2- ethylhexyl

TRiAM 1 17.0

EC41 BP8 MCT 40 1.20 0.15 0.75 -4- 0.90 mL 3.00 3,400 27.57 68.60 70.90 1.30 -1

O 0

methoxyci

nnamate

Fragranc

EC42 BP5 MCT 40 1.20 TEOS 0.16 0.74 0.90 mL 3.00 3,400 0.76 2.60 7.1 1 3.48 2.45 -6.

e

P5 Na Fragranc

EC43 B MCT 40 1.20 0.1 1 0.90 0.90 mL 3.00 3,400 2.99 6.15 12.97 7.18 1.62 -3

Silicate e

Fragranc

EC44 BP5 MCT 40 1.20 APTMS 0.15 0.75 0.90 mL 3.00 3,400 1.31 8.72 24.90 1 1.97 2.70 +4 e

2- ethylhexyl

EC45 BP5 MCT 40 1.20 TEOS 0.16 0.74 -4- 0.90 mL 3.00 3,400 0.62 25.33 49.13 26.90 1.91 -7.

methoxyci

nnamate

2- ethylhexyl

BP5 Na

EC46 MCT 40 1.20 0.1 1 0.90 -4- 0.90 mL 3.00 3,400 10.50 24.00 53.93 28.67 1.81 -41

Silicate

methoxyci

nnamate

2- ethylhexyl

EC47 BP5 MCT 40 1.20 DAMO 0.15 0.75 -4- 0.90 mL 3.00 3,400 4.57 14.97 41.77 19.37 2.48 -0.

methoxyci

nnamate

2- ethylhexyl

BP5 TRiAM

EC48 MCT 40 1.20 0.15 0.75 -4- 0.90 mL 3.00 3,400 4.61 15.27 46.53 20.83 2.74 -0.

O

methoxyci

nnamate

Fragranc

EC49 BP5 MCT 40 1.20 DAMO 0.15 0.75 0.90 mL 3.00 3,400 1.59 4.44 1 1.17 5.54 2.16 +7 e

EC50 BP22 MCT 30 1.60 APTMS 0.15 1.25 3.00 3,400 1 1.40 38.80 91.77 45.97 2.07 +6

EC51 BP22 MCT 30 1.28 APTMS 0.12 1.00 3.60 3,400 10.37 30.43 66.23 35.00 1.84 +4

EC52 BP22 MCT 30 0.98 APTMS 0.09 0.75 4.20 3,400 9.63 30.67 64.50 34.33 1.79 +3

EC53 BP24 MCT 30 1.60 APTMS 0.15 1.25 3.00 3,400 15.60 41.73 90.30 48.03 1.79 +2

EC54 BP24 MCT 30 1.28 APTMS 0.12 1.00 3.60 3,400 16.10 41.57 87.50 48.03 1.72 -1

EC55 BP24 MCT 30 0.98 APTMS 0.09 0.75 4.20 3,400 15.20 45.40 94.60 50.90 1.75 -1.

^** sample was formed in a 100 mL equipment chamber

Determination of linear vs branched emulsion stability

In order to determine the intrinsic stability of emulsions prepared stabilised with a linear and branched amphiphilic copolymer emulsions were prepared using the branched copolymer BP8 and the linear example LP2 using MCT as the internal phase using General Emulsification Route 1

Laser diffraction measurements were carried out using a Malvern Mastersizer 3000 with a Hydro LV cell. The samples were added to the Hydro LV cell which contains 500 mL of deionised water to an obscuration of 4-5%. The stirrer speed of the cell was set to 1800 rpm and the diameter of the emulsion droplets were measured every minute for 1 hour.

The data clearly shows the higher stability of the emulsions prepared using the branched polymer BP8compared to the linear polymer LP2. In the case of the emulsions prepared with the linear equivalent polymer the emulsion droplet diameter decreases significantly over the one hour measurement period as shown by the laser diffraction analyses. This deviation over time would provide

production issues as emulsions prepared using linear polymers would destabilise over time and as such the "locking-in" stage of crosslinking to form encapsulates would give rise to different encapsulate sizes due to the changes in emulsion droplet sizes. In comparison, emulsions prepared using branched polymers have a higher inherent stability due to the amphiphilic copolymer's architecture. As such, these stable droplets can then be crosslinked within longer time periods to form capsules where the size is consistent with the size of the formed emulsions.