Technical Field

[1 ] The present invention relates to polymerisable compositions comprising one or more vinyl monomers, to methods of producing polymerised compositions by polymerising one or more vinyl monomers, and to polymers comprising polymerised residues of one or more vinyl monomers. In each case, the vinyl monomers include at least a monomer compound having the structure of Formula I:

Formula I wherein R ^p is an organyl group comprising a polymerisable ethylenically unsaturated functional group.

Background of Invention

[2] Paints and coating compositions for many industrial applications include vinyl monomers, typically carried together with polymerisation initiators, pigments and fillers in a solvent. Once applied to a substrate, the monomers are induced to polymerise to form a solid polymeric coating. Such coatings, including automotive coatings for both original equipment manufacturer (OEM) and refinishing applications, are commonly required to have excellent thermal stability, particularly when subjected to a high temperature baking process, as well as excellent rigidity/hardness.

[3] Coating compositions including isobornyl methacrylate (IBMA) as a co monomer have been found to produce a good balance of properties for automotive and other demanding coating applications. The bulky bicyclic isobornyl ring imparts a high glass transition temperature to the polymerised coatings, thus providing satisfactory hardness and wear resistance, and IBMA-containing co-polymers exhibit excellent thermal stability. Similar performance advantages are provided in reactive resin systems for adhesives, sealants, or composites. A further advantage of IBMA is that it may be derived from a renewable resource.

[4] While IBMA provides satisfactory coating properties for some applications, it is desirable for certain demanding applications that further improvements in thermal stability and hardness of polymeric coatings are provided. Moreover, it is generally desirable to minimise the quantity of expensive speciality monomers, such as IBMA, used in a polymerisable formulation while maintaining acceptable properties of the resultant polymerised composition. In addition to meeting performance requirements, alternative monomers to IBMA should ideally also be bio-derived from sustainable resources.

[5] There is therefore an ongoing need for new polymerisable compositions, and vinyl monomers for inclusion in such compositions, which at least partially address one or more of the above-mentioned short-comings, or at least provide a useful alternative.

[6] A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that the document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Summary of Invention

[7] In accordance with a first aspect the invention provides a polymerisable composition comprising: one or more vinyl monomers, the one or more vinyl monomers comprising a compound having the structure of Formula I:

Formula I wherein R ^p is an organyl group comprising a polymerisable ethylenically unsaturated functional group; and a polymerisation initiator or catalyst.

[8] In some embodiments, R ^p is (i.e. consists of) the polymerisable ethylenically unsaturated functional group.

[9] In some embodiments, R ^p has the structure:

wherein R ¹ is -H or an alkyl group. In some such embodiments, R ¹ is methyl (Me).

[10] In some embodiments, the compound having the structure of Formula I has the structure:

[11 ] In some embodiments, the one or more vinyl monomers comprise at least one further vinyl monomer. The at least one further vinyl monomer may comprise at least one compound selected from the group consisting of: styrene, (meth)acrylates, acrylic acid and vinyl esters. The compound having the structure of Formula I may be present in an amount of between about 1 wt % and about 40 wt % of the one or more vinyl monomers.

[12] In some embodiments, the polymerisation initiator or catalyst comprises a free radical polymerisation initiator.

[13] In some embodiments, the polymerisable composition further comprises a solvent. The solvent may optionally be dihydrolevoglucosenone. [14] In accordance with a second aspect, the invention provides a method of producing a polymerised composition comprising polymerising one or more vinyl monomers, the one or more vinyl monomers comprising a compound having the structure of Formula I:

wherein R ^p is an organyl group comprising a polymerisable ethylenically unsaturated functional group.

[15] In some embodiments, R ^p is (i.e. consists of) the polymerisable ethylenically unsaturated functional group.

[16] In some embodiments, R ^p has the structure:

wherein R ¹ is -H or an alkyl group. In some such embodiments, R ¹ is Me.

[17] In some embodiments, the compound having the structure of Formula I has the structure:

[18] In some embodiments, the one or more vinyl monomers comprise at least one further vinyl monomer. The at least one further vinyl monomer may comprise at least one compound selected from the group consisting of: styrene, (meth)acrylates, acrylic acid and vinyl esters. The compound having the structure of Formula I may be present in an amount of between about 1 wt % and about 40 wt % of the one or more vinyl monomers.

[19] In some embodiments, the one or more vinyl monomers are polymerised in the presence of a polymerisation initiator or catalyst. The polymerisation initiator or catalyst may comprise a free radical polymerisation initiator.

[20] In some embodiments, the one or more vinyl monomers are polymerised in a solvent. The solvent may optionally be dihydrolevoglucosenone.

[21 ] In some embodiments, the method further comprises heating the polymerised composition to a temperature of above 160°C, preferably above 170°C.

[22] In accordance with a third aspect, the invention provides a polymerised composition, produced by a method according to any of the embodiments disclosed herein.

[23] In accordance with a fourth aspect, the invention provides a polymer comprising polymerised residues of one or more vinyl monomers, the one or more vinyl monomers comprising a compound having the structure of Formula I:

wherein R ^p is an organyl group comprising a polymerisable ethylenically unsaturated functional group.

[24] In some embodiments, R ^p is (i.e. consists of) the polymerisable ethylenically unsaturated functional group.

[25] In some embodiments, R ^p has the structure: wherein R ¹ is -H or an alkyl group. In some such embodiments, R ¹ is Me.

[26] In some embodiments, the compound having the structure of Formula I has the structure:

[27] In some embodiments, the one or more vinyl monomers comprise at least one further vinyl monomer. The at least one further vinyl monomer may comprise at least one compound selected from the group consisting of: styrene, (meth)acrylates, acrylic acid and vinyl esters.

[28] In some embodiments, polymerised residues of the compound having the structure of Formula I are present in the polymer in an amount of between about 1 wt % and about 40 wt % of the polymer.

[29] In some embodiments, the polymer has a number-averaged molecular weight (M _n ) of between about 5,000 and about 50,000 g/mol.

[30] In some embodiments, the polymer has the structure of Formula II: Formula II wherein: each R ² and R ³ is independently -H or Me; each R ⁴ is independently a phenyl group or -C(=0)0R ⁵ , wherein each R ⁵ is independently H or a Ci to C20 organyl group; n is a mass fraction of from above 0 to 1 , n’ is a mass fraction of from 0 to 1 and n + n’ = 1 ; and X ¹ and X ² are independently selected polymer end groups.

[31 ] In accordance with a fifth aspect, the invention provides a coating comprising a polymer according to any of the embodiments disclosed herein.

[32] In accordance with a sixth aspect, the invention provides a compound having the structure of Formula lb:

wherein R ¹ is an alkyl group.

[33] In some embodiments, the compound has the structure: [34] In some embodiments, R ¹ is Me.

[35] In accordance with a seventh aspect, the invention provides a method of producing a compound according to Formula lb, the method comprising:

(a) reducing a compound having the structure of Formula III to produce a compound having the structure of Formula IV:

Formula III Formula IV

(b) reacting the compound having the structure of Formula IV with a compound having the structure of Formula V to produce a compound having the structure of Formula lb:

Formula IV Formula V Formula lb wherein: R ¹ is an alkyl group; and X is selected from the group consisting of: OH, 0-C(=0)-C(=CFl2)-R ¹ and a leaving group.

[36] In some embodiments, the compound having the structure of Formula V is methacrylic anhydride. [37] Where the terms“comprise”,“comprises” and“comprising” are used in the specification (including the claims) they are to be interpreted as specifying the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereof.

[38] Further aspects of the invention appear below in the detailed description of the invention.

Brief Description of Drawings

[39] Embodiments of the invention will herein be illustrated by way of example only with reference to the accompanying drawings in which:

[40] Figure 1 is an ¹ FI NMR spectrum of (-)-6,8-dioxabicyclo[3,2,1 ]octan-4-yl methacrylate, a compound according to Formula I, as produced in Example 1.

[41 ] Figure 2 is an ¹ FI NMR spectrum of a homopolymer of (-)-6,8- dioxabicyclo[3,2,1 ]octan-4-yl methacrylate, as produced in Example 2.

[42] Figure 3 depicts results from the thermogravimetric analysis of homopolymers of (-)-6,8-dioxabicyclo[3,2,1 ]octan-4-yl methacrylate, as produced in the bulk phase and the emulsion phase in Example 2.

[43] Figure 4 depicts comparative plots of the rate of conversion of (-)-6,8- dioxabicyclo[3,2,1 ]octan-4-yl methacrylate (m-Cyrene) vs IBMA in homopolymerisation reactions in various solvents: (a) dimethylsulfoxide, (b) gamma valerolactone and (c) dihydrolevoglucosene, as investigated in Example 3.

[44] Figure 5 is a plot of the rate of conversion of (-)-6,8- dioxabicyclo[3,2,1 ]octan-4-yl methacrylate in homopolymerisation reactions in dimethylsulfoxide (DMSO); dihydrolevoglucosene (Cyrene), gamma valerolactone (GVL) and methyl isobutyl ketone (MIBK), as investigated in Example 3.

[45] Figure 6 depicts Fineman-Ross (F-R) and Kelen-TCidos (K-T) graphical plots for copolymers of (-)-6,8-dioxabicyclo[3,2,1 ]octan-4-yl methacrylate and IBMA, as investigated in Example 5. [46] Figure 7 depicts comparative results from the thermogravimetric analysis of polymerised coating compositions either including or excluding (-)-6,8- dioxabicyclo[3,2,1 ]octan-4-yl methacrylate as one of the vinyl monomers, as produced in Example 6.

[47] Figure 8 is a graph of FIACAT skin cell viability after exposure to (-)-6,8- dioxabicyclo[3,2,1 ]octan-4-yl methacrylate for varying lengths of time, as investigated in Example 8.

Detailed Description

[48] The present invention relates to polymerisable compositions, including but not limited to coating compositions, which comprise one or more vinyl monomers, and to methods of producing polymerised compositions, including but not limited to coatings, from such compositions. The invention also relates to polymers comprising polymerised residues of one or more vinyl monomers. In each case, the vinyl monomers include a compound having the structure of Formula I:

Formula I

wherein R ^p is an organyl group comprising a polymerisable ethylenically unsaturated functional group, for example a (meth)acrylate group. In some preferred embodiments, R ^p is a polymerisable ethylenically unsaturated functional group.

[49] The inventors have found that homopolymers and copolymers of such a monomer provide high thermal stability, high glass transition temperature and/or high hardness, in at least some cases matching or exceeding those of equivalent polymers incorporating IBMA. Moreover, comparative studies have indicated that a methacrylate-functionalised monomer according to Formula I has a higher reactivity in free radical polymerisation than IBMA.

[50] Without wishing to be bound by any theory, the inventors consider that the favourable thermal and glass transition properties may be attributed at least in part to this higher reactivity, which may provide a higher molecular weight polymer compared to equivalent IBMA-based formulations. Moreover, as seen in Scheme 1 , the bicyclic ring moiety of a Formula I molecule, i.e. structure (1 a) in Scheme 1 , provides a similar structural motif to the isobornyl bicyclic moiety in IBMA, i.e. structure (1 b) in Scheme 1 , and can thus be expected to impart similar or even improved properties such as rigidity, harness and thermal stability to polymers incorporating these monomers.

(1 a) (1 b)

Scheme 1

[51 ] It is considered a further advantage that the compounds having the structure of Formula I can be prepared from renewable feedstocks, in high yields and via scalable methodologies. In particular, the monomers may be prepared from levoglucosenone or its derivative dihydrolevoglucosenone, depicted in Scheme 2 as structures (2a) and (2b) respectively. These compounds are derived from fast pyrolysis of renewable cellulosic resources, including Australian pine wood. Dihydrolevoglucosenone, sold as “Cyrene”, is a green (i.e. renewably-sourced) solvent with applications as a replacement for polar industrial solvents.

[52] As used throughout this specification, a dashed double bond as depicted in structure (2c) of Scheme 2 encompasses in the alternative either a double bond, as in structure (2a) in Scheme 2, or a single bond as in structure (2b) in Scheme 2.

Scheme 2 Polymerisable compositions

[53] The invention relates to polymerisable compositions comprising one or more vinyl monomers including a compound having the structure of Formula I:

wherein R ^p is an organyl group comprising a polymerisable ethylenically unsaturated functional group. The compositions generally include a polymerisation initiator or catalyst which allows polymerisation of the monomers to be induced.

[54] As used herein, a polymerisable ethylenically unsaturated functional group is a functional group comprising a carbon-carbon double bond capable of polymerising and/or copolymerising with the polymerisable ethylenically unsaturated functional groups of other comonomers to form a polymer having an extended alkane (... -C-C-C-C-C-... ) backbone chain. Considering the important role of the bicyclic ring structure of the compound of Formula I in the resultant polymer, the R ^p group is not considered to be particularly limited, and may include a variety of ethylenically unsaturated functional groups known in the polymer art, and in particular those which contain a polymerisable vinyl or vinylidene group. As used herein, a“vinyl group” is a monovalent group having the structure -CFI=CFl2. As used herein, a “vinylidene group” is a monovalent group having the structure -CR”=CFl2 wherein R” is an organyl group, such as methyl (Me).

[55] In preferred embodiments, R ^p consists of (i.e. is) a polymerisable ethylenically unsaturated functional group. Flowever, it is also envisaged that R ^p may suitably include a linking group between the bicyclic ring moiety and the polymerisable ethylenically unsaturated functional group, for example a linear hydrocarbylene or polyethylene oxide chain.

[56] For embodiments where R ^p is a polymerisable ethylenically unsaturated functional group, suitable R ^p functional groups may include the acryloyl group, i.e. -C(=0)CFI=CFl2, the alkyl acryloyl group, i.e. -C(=0)CR ¹ =CFl2 where R ¹ is an alkyl group (preferably Me), the vinyl group and the allyl group, i.e.— CH2CH=CH2, such that the corresponding compounds of Formula I include acrylate, alkyl acrylate, vinyl ether and allyl ether groups, which are known to be polymerisable by free radical and/or anionic polymerisation mechanisms. In some embodiments, R ^p is acryloyl or methacryloyl. The inventors have found in particular that methacrylate compounds according to Formula I, where R ^p is methacryloyl, provide polymers with glass transition and thermal stability properties favourable for certain coating applications.

[57] As indicated by the dashed double bond, the compound having the structure of Formula I may have either a saturated bicyclic ring structure or a double bond at the indicated ring position. In some embodiments, the bicyclic ring structure is saturated, i.e. the compound having the structure of Formula I has the structure of Formula la:

[58] It will be appreciated that the Formula I molecule is chiral. The compounds according to Formula I are typically derived from bio-derived levoglucosenone, or its reduced derivative dihydrolevoglucosenone, which are levorotarory; i.e. (-), as depicted in structure 3(a) of Scheme 3. In the natural form, these molecules are believed to be substantially chirally pure. The chiral connectivity of the bicyclic ring structure may in some embodiments be maintained in the compound according to Formula I. Flowever, the compound according to Formula I includes a new chiral centre, marked with an asterisk (*) in Scheme 3, as a result of the reduction of the ketone moiety in the levoglucosenone or dihydrolevoglucosenone staring material. In some embodiments, therefore the compound according to Formula I comprises either one of, or a mixture of, the stereochemically isomeric structures (3b) and (3c) depicted in Scheme 3, depending on the stereospecificity of the reduction reaction. [59] The compound according to Formula I may be the only vinyl monomer in the polymerisable composition, such that a homopolymer of the compound is producible. In some embodiments, however, the polymerisable composition comprises one or more further vinyl monomers.

[60] As used herein, a vinyl monomer is an ethylenically unsaturated monomer capable of polymerising and/or copolymerising with other vinyl monomers to form a polymer having an extended alkane (... -C-C-C-C-C-... ) backbone chain, and includes monomers with polymerisable vinyl or vinylidene groups.

[61 ] A large number of vinyl monomers are known in the polymerisation art, and the polymerisable composition may generally comprise any one of more of these as further vinyl monomers. Such monomers include, among others, vinyl aromatics, vinyl esters, vinyl ethers, vinyl chloride, allyl esters, allyl ethers, acrylic monomers and the like. Examples of suitable vinyl aromatics may include styrene and substituted styrenes. Examples of suitable vinyl esters and vinyl ethers may include vinyl acetate and 2-hydroxyethyl vinyl ether. Examples of suitable allyl esters and allyl ethers may include allyl acetate and allyl ethyl ether. Examples of suitable acrylic monomers may include alkyl (meth)acrylates such a methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, hexyl(meth)acrylate, and 2-ethylhexyl (meth)acrylate, substituted alkyl (meth)acrylates such hydroxyethyl methacrylate, cyclic (meth)acrylates such a IBMA and dihydro-5-hydroxyl furan-2-yl methacrylate, acrylic acid, (meth)acrylamides, and acrylonitrile. As used herein, a“(meth)acrylate” includes in the alternative both an acrylate and a methylacrylate. [62] Particularly preferred vinyl monomers are those capable of undergoing facile free radical polymerisation reactions. In some embodiments, the further vinyl monomers include one or more selected from styrene, (meth)acrylates, acrylic acid and vinyl esters. In some embodiments, the further vinyl monomers include one or more selected from styrene and methacrylates. The methacrylates may include alkyl methacrylates, such as methyl methacrylate and butyl methacrylate, and cyclic organyl methacrylates, such as IBMA and dihydro-5-hydroxyl furan-2-yl methacrylate.

[63] The polymerisable composition may optionally further comprise multi functional vinyl monomers, i.e. compounds with two or more ethylenically unsaturated functional groups which produce cross-links between polymer chains when co polymerised with mono-functional vinyl monomers. However, for some applications, such as certain paint and coating applications, it is preferred that the polymers are not cross-linked, or only cross-linked post-polymerisation, and accordingly the polymerisable composition may in some embodiments exclude the presence of multi functional vinyl monomer cross-linkers.

[64] The inventors have found that the compounds having the structure of Formula I provide improved polymer properties compared with equivalent IBMA- containing polymers (for example higher molecular weight and hardness), and thus consider that compounds having the structure of Formula I may be useful as an alternative monomer to IBMA. Accordingly, the polymerisable composition may comprise one or more further vinyl monomers as conventionally formulated for co polymerisation with IBMA. Furthermore, the inventors consider that these improved properties may be useful either to provide higher performing polymerised compositions or polymerised compositions with similar performance but requiring lower amounts of the bicyclic ring-containing monomer.

[65] In embodiments where a mixture of vinyl monomers is present, the compound having the structure of Formula I may be present in any suitable amount to produce a copolymer, such as from 1 wt % to 99 wt % of the total amount of vinyl monomer. In some embodiments, the compound having the structure of Formula I is present in an amount of between about 1 wt % and about 40 wt %, or between about 5 wt % and about 25 wt %, or between about 10 wt % and about 20 wt % of the total amount of vinyl monomer. [66] The polymerisable composition generally includes a polymerisation initiator or catalyst to induce polymerisation of the vinyl monomers therein. In some embodiments, the polymerisation initiator or catalyst is a free radical polymerisation initiator. A large number of suitable free radical polymerisation initiators are available to those skilled in the art of polymerisation chemistry, including azo compounds such as azobisisobutyronitrile (AIBN) and inorganic and organic peroxides such as di-fe/f- amyl peroxide, dicumyl peroxide and benzoyl peroxides. The initiator may be selected from the group consisting of: acyl peroxides such as acetyl and benzoyl peroxides, alkyl peroxides such as cumyl and t-butyl peroxides, hydroperoxides such as t-butyl and cumyl hydroperoxides, peresters such as t-butyl perbenzoate, acyl alkylsulfonyl peroxides, dialkyl peroxydicarbonates, diperoxyketals, ketone peroxides, 2,2’-azobisisobutyronitrile, 2,2’-azobis(2,4-dimethylpentanenitrile), 4,4’-azobis(4- cyanovaleric acid), and 1 ,T-azobis(cyclohexanecarbonitrile).

[67] In some embodiments, the initiator is an anionic polymerisation initiator, for example fluorenyl Na ⁺ or diphenyl methyl Na.

[68] The polymerisation initiator or catalyst may be configured to induce polymerisation in response to a stimulus, such that polymerisation of the composition may be triggered by a user at a desired time. For example, a photoinitiator such as an aromatic ketone may be used to induce polymerisation in response to radiation, such as UV-radiation. An example of a suitable photoinitiator for acrylic monomers is 2,2-dimethoxy-2-phenylacetophenone.

[69] The polymerisation initiator or catalyst may be present in any suitable amount required to induce polymerisation, and it will be appreciated that this amount will dependent on various factors including the nature of the initiator or catalyst and the reaction conditions. In embodiments where a free radical initiator is used, for example, the free radical initiator may be present in an amount of 1 to 4 wt % of the polymerisable composition.

[70] The polymerisable composition may include additives for control of molecular weight or molecular weight distribution in the polymerisation, for example reversible addition fragmentation chain-transfer (RAFT) agents or atom transfer radical polymerisation (ATRP) initiators and catalysts. [71 ] The polymerisable composition may further include a solvent (or diluent). The inventors have demonstrated that vinyl monomers comprising a compound according to Formula I are polymerisable in a wide range of solvents, including non polar solvents such as xylene, polar high-boiling solvents such as dimethylsulfoxide (DMSO) and green solvents such as dihydrolevoglucosenone (“Cyrene”) and gamma- valerolactone. In some embodiments, the solvent is dihydrolevoglucosenone, which the inventors have found to promote very high reactivities and molecular weights. Without wishing to be bound by any theory, the inventors believe that this high reactivity in dihydrolevoglucosenone solvent is due to the structural similarity and the complementary polarity of the solvent and monomer molecules. In some embodiments, for example in coating compositions, the solvent may be present in an amount of from about 10 wt % to about 80 wt %, such as or from about 25 wt % to about 80 wt %, or from about 20 wt % to about 60 wt % of the polymerisable composition.

[72] The polymerisable composition may be a coating composition, for example for automotive coating applications. The polymerisable composition may be a powder coating, a high solids coating, a primer, a base coat or a top coat. Alternatively, the polymerisable composition may be an adhesive, a sealant, or a composite. Consistent with the intended application, the polymerisable composition may comprise one or more functional materials, for example pigments and fillers.

Methods of producing a polymerised composition

[73] The invention also relates to methods of producing a polymerised composition. The methods include polymerising one or more vinyl monomers comprising a compound having the structure of Formula I:

wherein R ^p is an organyl group comprising a polymerisable ethylenically unsaturated functional group, for example a (meth)acrylate group. [74] The nature and amounts of the vinyl monomers, including the compound having the structure of Formula I and optionally one or more further vinyl monomers, and the optional solvent and functional additives present when polymerising the vinyl monomers, are as described herein for the polymerisable compositions of the invention.

[75] The methods of the invention may comprise polymerising the one or more vinyl monomers in the presence of a polymerisation initiator or catalyst, for example those disclosed herein as components of the polymerisable compositions of the invention. The methods may include applying a stimulus to induce polymerisation, for example irradiating the vinyl monomer composition with actinic radiation, such as UV light, or heating the vinyl monomer composition to thermally induce polymerisation. The polymerisation initiator or catalyst may be present in a suitable amount to induce polymerisation, as described herein.

[76] The methods may include a step of applying a coating composition, comprising the one or more vinyl monomers together with optional further components such as the polymerisation initiator or catalyst, solvent and functional additives, to a substrate, and inducing polymerisation of the polymers. Generally, at least part of the polymerisation reaction occurs after the application of the composition to the substrate. The polymerisation of the vinyl monomers on the substrate thus results in the formation of a coating with good adhesion to the substrate and satisfactory coating properties.

[77] The polymerisation may be conducted at an elevated temperature, for example a temperature from about 30°C up to about 150°C, depending on the application and monomer composition.

[78] Polymerisation may suitably be conducted in the bulk phase, i.e. where the monomers form the liquid reaction phase in the absence of a solvent, or in the solution phase, i.e. in the presence of a solvent, or in an emulsion. In emulsion phase polymerisation, the monomer-containing phase during polymerisation is dispersed in a continuous phase (typically an aqueous continuous phase) using a surfactant. The inventors have found that emulsion homopolymerisation of a compound according to Formula I produces a polymer with particularly high yield, molecular weight and glass transition temperature. Without wishing to be bound by any theory, this may be due to the combined advantages of bulk and solution polymerisation provided by emulsion polymerisation, i.e. bulk phase intrinsic kinetics but excellent heat dispersion from the micellar“micro-reactors” into the aqueous continuous phase.

[79] In some applications, for example certain vehicle OEM coating applications, the composition may be subjected to a further heating step after polymerisation, for example at a temperature of up to about 180°C or even 190°C. Such a high temperature post-polymerisation treatment step may advantageously increase the molecular weight and yield of the polymer and drive off residual solvent. The inventors have found that the polymerised compositions produced by the methods of the invention are advantageously able to withstand high temperature treatments while avoiding unacceptable thermal degradation. In some embodiments, the composition may be cross-linked after polymerisation, as part of a curing step. Suitable cross-linkers to effect cross-linking may include amine and isocyanate cross linkers, among others. The cross-linkers are typically added after polymerisation is complete to avoid formation of an overly cross-linked gel composition.

Polymers

[80] The invention also relates to polymerised compositions, produced by a method according to any of the embodiments disclosed herein, and to a polymer comprising polymerised residues of one or more vinyl monomers comprising a compound having the structure of Formula I:

wherein R ^p is an organyl group comprising a polymerisable ethylenically unsaturated functional group, for example a (meth)acrylate.

[81 ] The polymer of the invention is generally a vinyl polymer, i.e. an addition polymer of one or more vinyl monomers comprising an extended alkane (... -C-C-C-C- C-... ) backbone chain. The polymer may be a homopolymer of the compound having the structure of Formula I, or it may be a copolymer of this monomer and at least one further vinyl monomer. The nature of the vinyl monomer precursors, including the compound having the structure of Formula I and the optional further vinyl monomers, are as described herein for the polymerisable compositions of the invention.

[82] In embodiments where the polymer is a copolymer of the compound having the structure of Formula I and at least one further vinyl monomer, the polymerised residues of the compound according to Formula I may be present in any suitable amount in the copolymer, such as from about 1 wt % to about 99 wt % of the total amount of the polymer. In some embodiments, the polymerised residues of the compound having the structure of Formula I are present in an amount of between about 1 wt % and about 40 wt %, or between about 5 wt % and about 25 wt %, or between about 10 wt % and about 20 wt % of the polymer.

[83] The polymer may have a number-averaged molecular weight (M _n ) of between about 5,000 and about 50,000 g/mol. The inventors have found that homopolymerisation of a compound according to Formula I in polar solvents or an emulsion may advantageously produce a polymer with M _n in the range of about 30,000 g/mol to about 40,000 g/mol, and that binary copolymers with a M _n in the range of about 10,000 g/mol to about 25,000 g/mol may be produced in a polar solvent with a range of different vinyl comonomers.

[84] In embodiments where the polymer is a homopolymer of the compound according to Formula I, the polymer may have a glass transition temperature in the range of 160° to 190°C (as measured by differential scanning calorimetry; DSC), and exhibit stability up to about 300°C (as measured by thermal gravimetric analysis; TGA). For example, the polymer may have a 5% degradation temperature of at least 260°C and a 10% degradation temperature of at least 295°C in TGA.

[85] In some embodiments, the polymer has the structure of Formula II: Formula II wherein each R ² and R ³ is independently H or Me; each R ⁴ is independently a phenyl group or -C(=0)0R ⁵ wherein each R ⁵ is independently H or a Ci to C20 organyl group; n is a polymeric residue mass fraction of from above 0 to 1 , n’ is a polymeric residue mass fraction of from 0 to 1 and n + n’ = 1 ; and X ¹ and X ² are independently selected polymer end groups. It should be appreciated that the monomer residues of the structure according to Formula I may individually be inserted in either 1 ,2- or 2,1 - orientations, and may be randomly distributed or non-randomly distributed (e.g. in blocks or alternating) along the chain.

[86] It will be appreciated that the end groups X ¹ and X ² will depend on the nature of the chain initiation and chain termination mechanisms of the polymerisation reaction. In some embodiments, X ¹ and/or X ² are H. In other embodiments, at least one of X ¹ and X ² is a residue of the initiator.

[87] In some embodiments, each R ² is Me. In some embodiments, each R ⁴ is independently a phenyl group or -C(=0)0R ⁶ , wherein R ⁶ is FI or a Ci to C6 alkyl group.

[88] In some embodiments, n’ is 0, such that the polymer is a polymer only of one or more monomers according to Formula I. In other embodiments, n is from 0.001 to 0.4, or from 0.05 to 0.25, or from 0.1 to 0.2, such that the polymer is a copolymer of a monomer according to Formula I and one or more further vinyl monomers. Methods of producing compounds according to Formula I

[89] The invention also relates to methods of producing compounds according to Formula I. In a first reaction step, the methods involve reducing a compound having the structure of Formula III, such as levoglucosenone or dihydrolevoglucosenone, to produce an alcohol compound having the structure of Formula IV, according to Scheme 4:

Formula III Formula IV

Scheme 4

[90] The reduction reaction may be stereospecific, such that a single stereoisomer is produced selectively, or non-stereospecific, such that a mixture of exo and endo diastereomers is produced from the compound according to Formula III (even when chirally pure).

[91 ] In some embodiments, the reduced molecule according to Formula IV has a saturated bicyclic ring structure (i.e. the depicted dashed double bond represents a single bond). In such embodiments, the molecule may be prepared by a non- chemoselective reduction from the compound according to Formula III, whether it has a saturated or unsaturated ring. For example, if the compound according to Formula III has a saturated bicyclic ring (such as dihydrolevoglucosenone), reduction of only the ketone to an alcohol is required. This transformation may be effected with standard reducing agents known in the organic synthesis art, such as metal hydrides including lithium aluminium hydride and sodium borohydride. For example, the inventors have found that reduction of dihydrolevoglucosenone with lithium aluminium hydride affords the corresponding alcohol, according to Formula IV, in a yield of up to 95% in 2 hours at room temperature in tetrahydrofuran or diethyl ether. If, however, the starting material compound according to Formula III has an unsaturated bicyclic ring (such as levoglucosenone), the saturated compounds according to Formula IV may be prepared by a double reduction of both alkene and ketone functionalities, optionally in a single reaction step. Metal hydrides, such as lithium aluminium hydride, are believed to be suitable for this double reduction under appropriate reaction conditions.

[92] The reduction of dihydrolevoglucosenone or levoglucosenone to the corresponding ring-saturated alcohol (as a mixture of exo- and endo-stereoisomers) may alternatively be accomplished via catalytic reduction with dihydrogen (H2), for example with Pd/AbCb at 100°C as for example reported in Hydrogenation of Levoglucosenone to Renewable Chemicals, Siddarth H. Krishna, Daniel J. McClelland, Quinn A. Rashke, James A. Dumesic, George W. Huber. Green Chem., 2017, 19, 1278-1285. In this case, the reaction should be controlled, for example by limiting the reaction temperature to well below 150°C, to avoid over-reduction to species such as tetrahydrofurandimethanol. Other routes for the reduction of dihydrolevoglucosenone to the corresponding alcohol include reductions using microbes such as Bakers yeast or with chemical reducing agents such as sodium borohydride, lithium aluminium hydride or diisobutylaluminium hydride.

[93] In some embodiments, the reduced molecule according to Formula IV has an unsaturated bicyclic ring structure (i.e. the depicted dashed double bond represents a double bond). It will be appreciated that the precursor molecule according to Formula III will then also have an unsaturated bicyclic ring structure. The required reduction according to Scheme 4 is then a chemoselective 1 ,4-reduction of an enone to an enol. The inventors believe that this reaction can be performed using room temperature reduction with lithium aluminium hydride and sodium borohydride. The Luche reaction, using Ce(BH4)3 (derived from the combination of NaBH4 and CeCh) as the hydride source, is another example of a reaction known to be suitable for chemoselective reductions of a,b-unsaturated enones to ends.

[94] The methods further involve reacting the compound having the structure of Formula IV to produce the compound according to Formula I. This reaction may be conducted in a separate reaction step, for example after isolating and purifying the compound according to Formula IV produced via Scheme 4. However, it is not excluded that the reaction may be conducted as a one pot reaction. [95] As disclosed herein, the R ^p organyl group of the compound having the structure of Formula I may be a polymerisable ethylenically unsaturated functional group. Reactions for synthetically transforming primary alcohols into a variety of polymerisable ethylenically unsaturated groups are available to the person skilled in the art. In one set of embodiments, the compound according to Formula IV is reacted with a compound having the structure of Formula V to produce an acrylate or alkyl acrylate compound having the structure of Formula lb, according to Scheme 5:

Formula IV Formula V Formula lb

Scheme 5

wherein R ¹ is selected from the group consisting of: -FI and an alkyl group; and X is selected from the group consisting of: -OH, -0-C(=0)-C(=CFl2)-R ¹ and a leaving group. Suitable X leaving groups may include halogens, such as chlorine. In some embodiments, R ¹ is an alkyl group, such as Me.

[96] In some embodiments, the compound having the structure of Formula V is an anhydride, i.e. X is -0-C(=0)-C(=CFl2)-R ¹ . For example, the inventors have found that a methacrylate compound according to Formula lb may be produced via reaction of the corresponding alcohol according to Formula IV with methacrylic anhydride, in a yield of up to 89% in 12 hours at 50°C in ethyl acetate.

[97] In other embodiments where R ^p is a polymerisable ethylenically unsaturated functional group, R ^p is a vinyl or allyl functional group. In such embodiments, the compound according to Formula I may be produced by vinylation or allylation of the compound having the structure of Formula IV. Suitable conditions for vinylation of primary alcohols are reported in Direct vinylation of natural alcohols and derivatives with calcium carbide, Siew Ping Teong, Ariel Yi Hui Chua, Shiyun Deng, Xiukai Li and Yugen Zhang, Green Chem., 2017, 19, 1659-1662. Suitable conditions for allylation of primary alcohols are reported in Catalytic Dehydrative Allylation of Alcohols, Hajime Saburi, Shinji Tanaka, and Masato Kitamura, Angew. Chem. Int. Ed. 2005, 44, 1730 -1732.

EXAMPLES

[98] The present invention is described with reference to the following examples. It is to be understood that the examples are illustrative of and not limiting to the invention described herein.

Materials and characterisation methods

[99] Dihydrolevoglucose (sold as “Cyrene”) was provided by Circa group, Australia. Methyl methacrylate (MMA), styrene, hydroxy ethylmethacrylate (HEMA), isobornyl methacrylate (IBMA), butyl methacrylate (BMA), and acrylic acid (AA) were purchased from Sigma-Aldrich and treated with basic alumina to remove the inhibitor. Methacrylic anhydride (MAN) was purchased from Sigma Aldrich and used as received. Azobisisobutyronitrile (AIBN) was provided by CSIRO, Luperox A75 (benzoyl peroxide) was purchased from Sigma Aldrich and used as received. Dihydro-5-hydroxyl furan-2-yl methacrylate (m-2H-HBO monomer) was synthesised according to a literature procedure.

[100] A Bruker DRX spectrometer (400 MHz, Me4Si as internal standard) was used to analyze ¹ H NMR and ¹³ C NMR in chloroform-d1 and dimethyl sulfoxide d6 (DMSO-d6) at room temperature. Infrared spectroscopy was performed using an Agilent Cary 630 FTIR. TGA was performed using Mettler TGA/DSC1 STAR with a heating rate to 10 °C/min from 20 to 500 °C under nitrogen atmosphere in a standard aluminum pan (sample weight: 1 -10 mg). A PerkinElmer DSC8000 was used for the DSC measurement with a heating rate of 10 °C/min in aluminum pans (sample weight: 10-20 mg). The samples were scanned from 0 to 140°C with a heating rate of 10 °C/min. Each sample was healed through three heating cycles to remove thermal history, and the glass transition temperature (T _g ) values were obtained from third heating cycle. The molecular weights of different polymer samples were measured by gel permeation chromatography (GPC) on a Tosoh EcosHLC-8320 equipped with UV detector (l = 280 nm) and refractive index detector with Tosoh alpha 2000 and 4000 columns. DMF with LiBr (10 mM) was used as eluent with a flow rate of 1 mL/min. The columns were calibrated with a series of polystyrene standards.

Example 1

[101] Dihydrolevoglucosenone (“Cyrene”; (-)-6,8-dioxabicyclo[3,2,1 ]octan-4-one, 10g, 78mmol) in 50ml diethyl ether was added dropwise into a solution of lithium aluminium hydride (3.26g, 86 mmol) in 100 ml diethyl ether at 0-4°C and then stirred at room temperature for two hours. The reaction mixture was then further diluted with 150ml diethyl ether and sodium sulphate dehydrate was added slowly keeping the reaction mixture in ice bath to avoid heat generation within the reaction vessel. The mixture was stirred until the whole mixture became completely white. The reaction mixture was filtered through Celite and excess solvent was evaporated to collect the final product. The reduced product, levoglucosanol, or (-)-6,8- dioxabicyclo[3,2,1 ]octan-4-ol, was thus obtained in 95% yield according to Scheme 6.

Scheme 6

[102] The product was confirmed as (-)-6,8-dioxabicyclo[3,2,1 ]octan-4-ol via NMR, FTIR and mass spectrometry: ¹ H NMR (400 MHz, CDCI3): d/ppm 1.48-1.60 (m, 1 H), 1.83-1.92 (m, 1 H), 1.98-2.02 (m, 2H), 3.55-3.60 (dd, 1 H), 3.77-3.84 (m, 2H), 4.47-4.48 (m, 1 H), 5.23 (s, 1 H). ¹³ C NMR (100 MHz, CDCI3): d/ppm 26.11 , 27.85, 68.17, 69.01 , 72.79, 102.93. ATR-FTIR: 3394, 2948, 1065 cm-1. ESI HRMS: cal 130.06 (CeHioOs, H ⁺ ), found m/z=131.1028 27.

[103] The (-)-6,8-dioxabicyclo[3,2,1 ]octan-4-ol intermediate (10 g, 77 mmol) and 4-dimethylaminopyridine (DMAP; 0.09 g, 0.77 mmol) were charged into a two neck round bottom flask followed by addition of 25 ml ethyl acetate. The flask was sealed and the mixture was stirred under argon to ensure a homogeneous solution. Methacrylic anhydride (MAN) (11.85 g, 77 mmol) dissolved in 10 ml ethyl acetate was added dropwise into the solution (~1 drop/s). After the completion of MAN addition, the solution was stirred at room temperature under argon for 3 hours followed by heating at 55°C for 24 hours. After the reaction, the solution was cooled to room temperature and further diluted with 100 ml ethyl acetate solution. The organic layer was washed three times with saturated NaHCC solution and was dried over anhydrous MgSCh for two hours. The organic layer was then filtered and solvent was evaporated to collect pure methacrylated Cyrene (m-Cyrene; (-)-6,8- dioxabicyclo[3,2,1 ]octan-4-yl methacrylate) in 89% yield according to Scheme 7.

Scheme 7

[104] The product was confirmed as (-)-6,8-dioxabicyclo[3,2,1 ]octan-4-yl methacrylate via NMR, FTIR and mass spectrometry: ¹ H NMR (400 MHz, CDCh): d/ppm 1.59-1.64 (m, 1 H), 1.74-1.82 (m, 1 H), 1.89-1.90 (t, 3H), 1.92-2.00 (m, 2H), 3.78-3.81 (m, 1 H), 3.88-3.90 (d, 1 H), 4.49-4.51 (m, 1 H), 4.72-4.77 (m, 1 H), 5.38 (s, 1 H), 5.52-5.55 (t, 1 H), 6.10-6.12 (t, 1 H). ¹³ C NMR (100 MHz, CDCh): d/ppm 18.16, 21.75, 27.77, 68.40, 71.52, 73.03, 100.39, 125.96, 135.97, 166.60. ATR-FTIR: 2957, 1714, 1636, 1030 cm ¹ . ESI: cal 198.09 (C10H14O4, H ⁺ ), found m/z= 199.0955.

Example 2

[105] Homopolymerisation of m-Cyrene according to Scheme 8 was investigated, in the bulk phase, solution phase and emulsion as seen in Table 1. For the bulk phase polymerisation, azobisisobutyronitrile (AIBN; 0.01 g, 0.06 mmol) was added to m-Cyrene (1 g, 5 mmol), and the mixture was heated to 70°C for 6 hours. For solution phase polymerisation, AIBN (0.01 g, 0.06 mmol) was added to a solution of m-Cyrene (1 g, 5 mmol) in solvent (4 g), and the mixture was heated to 70°C for 6 hours. [106] Emulsion polymerisation of m-Cyrene monomer was undertaken using the following procedure: sodium dodecyl sulphate (SDS; 0.05 g, 5 wt% w.r.t monomer) was added into 3 ml water (for 20% solid content) in a two-neck round bottom flask. The mixture was heated to 65°C with continuous stirring under argon for 15 mins to ensure complete dissolution of SDS in water. The system was then sealed and heated further to 80°C and ammonium persulfate (APS; 0.01 g, 0.004 mmol) in 1 ml water was added. Immediately, m-Cyrene (1 g, 5 mmol) was added slowly (~1 drop/sec) and the whole mixture was allowed to stir at 80°C for 6 hours. After the reaction was finished, a milky, white emulsion was first centrifuged and was washed with methanol, ethanol and water respectively to remove the emulsifier. The solid polymer was then dried at 45°C under vacuum until being at constant weight.

[107] The resultant polymers were characterised by ¹ H NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Representative ¹ H NMR spectra of m-Cyrene and its homopolymer (prepared in Cyrene solvent) are depicted in Figures 1 and 2 respectively. The NMR spectrum of the polymer lacks peaks for vinylic protons and shows a new peak for the backbone alkyl chain protons (“k” in Figure 2). Moreover, the peaks characteristic of the bicyclo Cyrene ring structure have broadened but not substantially shifted. This confirms that the polymer forms without ring opening or other change in the ring structure.

Scheme 8

[108] Solution polymerisation was successfully performed in a wide range of solvents, ranging from non-polar xylene to high boiling, polar dimethylsulfoxide (DMSO) as well as green solvents like Cyrene and gamma-valerolactone. The polymer was found to precipitate out (partially) from xylene with the progression of polymerisation, consistent with the expected polarity of the polymer. The polymer remained soluble in reactions solvents like DMSO, Cyrene and g-valerolactone, and the highest molecular weights and yields were also obtained in these solvents. Emulsion polymerisation gave the highest yields and molecular weight of the homopolymer.

[109] The glass-transition temperature (T _g ) of the m-Cyrene homopolymer, as determined by DSC, was found to range between c.a. 160°C for bulk polymerisation to c.a. 190°C for emulsion polymerisation. The T _g is thus comparable to that for IBMA homopolymer (T _g from 160-180°C).

[110] As seen in Figure 3, TGA indicates that the homopolymer is stable up to 290°C (for bulk phase polymerisation) or 310°C (for emulsion polymerisation). Such stabilities are considered acceptable for automotive OEM and refinish applications which require high temperature baking of polymerised compositions.

Table 1.

Example 3

[111] The comparative rates of homopolymerisation of m-Cyrene and IBMA were investigated in a number of different solvents, including Cyrene, dimethylsulfoxide (DMSO), methyl isobutyl ketone (MIBK) and gamma valerolactone (GVL). m-Cyrene (1 g, 5 mmol) or IBMA (1 g, 4.49 mmol) was added into 4 ml of the chosen solvent containing AIBN (0.1 g, 0.06 mmol) in a round bottom flask. Dimethoxy benzene (DMB) (20 mg, 0.144 mmol) was added into the solvent as an internal standard. The flask was sealed and the mixture was stirred under argon for half an hour to make a homogenous solution. Initial samples were taken for ¹ H NMR representing T=0 h. The solutions were heated at 72°C and samples were withdrawn at fixed intervals of time viz. T= 1 , 2, 3 h etc. ¹ H NMR measurements were used to calculate the monomer conversion for each sample. Comparative results are shown in Figure 4, including for the solvents DMSO, gamma valerolactone and Cyrene (Figures 4a - 4c), while the results for m-Cyrene in the different solvents is shown in Figure 5. m-Cyrene was found to react faster than IBMA in all the solvents, with the exception of MIBK where the rates were comparable. Its reaction rate is fastest in Cyrene, with the highest yield and molecular weight (M _n ; see Table 1 ).

Example 4

[1 12] Copolymerisation reactions of m-Cyrene with other vinyl monomers according to Scheme 9, using Cyrene as solvent, were investigated. The comonomers used were methyl methacrylate (MMA), styrene, dihydro-5-hydroxyl furan-2-yl methacrylate (m-2H-HBO), IBMA and butyl methacrylate (BMA). A molar ratio of 1 :9 (m-Cyrene: comonomer) and a solids content (20 wt %) was used for every reaction. AIBN (0.01 g, 0.06 mmol) was added to a solution of the monomers (1 g) in solvent (4 g), and the mixture was heated to 70°C for 6 hours.

Scheme 9 [113] The resultant binary copolymers were characterised by ¹ H NMR, GPC and DSC, and the results are shown in Table 2. The wt % comonomer in the polymers indicates preferential incorporation of m-Cyrene over each of the vinyl co-monomers tested, i.e. the m-Cyrene: comonomer incorporation ratio is greater than expected based on the monomer ratio (molar ratio of 1 :9) in the monomer reactant mixture, consistent with the fast kinetics of m-Cyrene polymerisation. The theoretical T _g of the copolymers matches well with the practical measurements, indicating good copolymerizaion of m-Cyrene with the comonomers. With styrene, m-Cyrene appears to form a block copolymer, thus giving rise to two T _g values.

Table 2.

[114] Investigations were also conducted at an m-Cyrene: comonomer molar ratio of 1 :1 ; however it was found that the resultant polymers were mainly a homopolymer of m-Cyrene. This is consistent with other observations of the fast kinetics of m-Cyrene polymerisation in Cyrene solvent, compared to the other vinyl monomers.

Example 5

[115] To quantify the relative reactivities of m-Cyrene and IBMA, a series of copolymerisation reactions were performed using mixtures of these monomers at different ratios. The results are shown in Table 3. Table 3.

^* M1 = mole fraction of m-Cyrene and M2= mole fraction of IBMA in feed, m1 = mole fraction of m-Cyrene and m2= mole fraction of IBMA in copolymer.

[1 16] From the values in Table 3, the reactivity ratio of m-Cyrene (r1 ) and IBMA (r2) were calculated using Fineman-Ross (F-R) and Kelen-TCidos (K-T) graphical methods. The linear relations are: model) (1) (K-T model) (2)

where, G = F(f— 1)//, H = F ² /f , h = G/(a + H , m = H/(ja + H),

F = M ₁ /M ₂ , f = m ₁ /m ₂

r _x = reactivity ratio of m-Cyrene, r ₂ = reactivity ratio of IBMA.

[1 17] Figure 6 depicts the F-R and K-T graphical plots for the m-Cyrene-IBMA copolymers, with the results tabulated in Table 4 confirming that m-Cyrene is more reactive than IBMA. Table 4.

Example 6

[118] The effect of m-Cyrene inclusion in a polymerisable composition comprising a mixture of other vinyl monomers was investigated. Two compositions suitable for powder coating applications, one with m-Cyrene (coating composition 6-1 ) and one without (coating composition 6-2) but otherwise identical, were formulated as seen in Table 5.

Table 5.

[119] The coating compositions were polymerised according to the following procedure. Most of the xylene (9.3 g) was added into a two neck round bottom flask. The flask was sealed and the system was stirred under argon for 30 min to ensure complete inert atmosphere. The system was then heated to 125°C. Once the temperature was reached and became constant, a mixture of the monomers, initiator and the remaining amount of xylene (0.3 g) was added dropwise (1 drop/ sec) into the system with continuous stirring. When the addition was complete, the reaction mixture was allowed to stir for 2 hours. After the polymerisation, the reaction was cooled. The cooled polymer solution was added drop wise into cold hexane with continuous stirring to precipitate out white polymer. The solid polymer was then filtered and washed two times with hexane and dried at 50°C under vacuum until constant weight is achieved.

[120] The polymerised coating compositions was then characterised by GPC and DSC, with the results shown in Table 6. It is evident that polymerisation of coating composition 6-1 , containing m-Cyrene as a co-monomer component, produces a higher molecular weight polymer. Furthermore, the polymer has a higher glass transition temperature, indicating improved rigidity.

Table 6.

[121] The thermal stability of the polymers was then investigated with TGA, with the results depicted in Figure 7. Major degradation of the polymer lacking m-Cyrene component (polymer of composition 6-2) started at 178°C. By contrast, major degradation of the polymer including m-Cyrene (polymer of composition 6-1 ) started only at 288°C, indicating the favourable thermal and stability properties imparted by the bulky bicyclic m-Cyrene monomer. The high temperature stability of the m- Cyrene containing polymer is considered acceptable for applications, including automotive OEM applications, which require high temperature baking of the polymerised coating compositions.

Example 7

[122] Flomopolymers of m-Cyrene and IBMA were prepared in dimethyl formamide (DMF), using 30 wt % monomer in DMF, AIBM initiator, and a 70°C reaction temperature for 4 hours. Thus, the monomer (m-Cyrene or IBMA; 1 g) and AIBN (0.01 g) in DMF (2.6g) was stirred in pre-dried round bottom flasks for 30 minutes at room temperature, and then at 70°C for 4 hours. The resultant polymer solutions were cooled and then drawn into a film with approx thickness of 10pm on a stainless steel plate (2x2 cm), using a draw down bar. The polymer film on the plate was then dried at 150°C for two minutes to remove the solvent.

[123] Vickers hardness tests were then performed on the dried solid films using a Micro Indenter analysis instrument. The homopolymer of IBMA had a Vickers hardness (HV) of 33.8 whereas the homopolymer of m-Cyrene has a Vickers hardness (HV) of 46.7. The results indicate that the bicyclic m-Cyrene monomer confers favourable hardness properties to polymers, where the performance exceeds that of IBMA (in the case of homopolymers at least).

Example 8

[124] The cytotoxicity of m-Cyrene was tested on HACAT skin cells. As m- Cyrene has a high boiling point, it is unlikely that exposure in use would occur through vapour inhalation, but exposure through skin contact is more likely. As seen in Figure 8, m-Cyrene is completely non-toxic for skin cells even after 48 hours at concentrations of 100mg/ml or lower, indicating the monomer to be safe to handle.

Example 9

[125] A variety of alternative synthetic methods have been demonstrated or are proposed for the reduction of dihydrolevoglucosenone, i.e. “Cyrene” to levoglucosanol.

[126] In one demonstrated example, a yeast-mediated reduction, according to the method of Sharipov et al, Mendeleev Commun., 2019, 29, 200-202, was used to reduce Cyrene. Thus, a suspension of baker’s yeast (S. cerevisiae) (Aldrich Type II, 23 g) in water (200 ml) was stirred at ca. 30 °C for 1 h, then a solution of Cyrene (39 mmol, 5 g) in water (20 ml) was added dropwise. The reaction mixture was stirred at ca. 30 °C, and the reaction was monitored by silica-gel thin layer chromatography (TLC) until the disappearance of the starting Cyrene (ca. 24 h). Then ethanol (200 ml) was added and further stirred for 1 h, the precipitate was filtered off, washed with ethanol and the solution obtained was combined with the filtrate. The filtrate was evaporated in vacuo, extracted with diethyl ether (3 X 50 ml_), dried over anhydrous magnesium sulphate and evaporated in vacuo. The residue was purified by column chromatography using silica gel to get 4.1 g levoglucosanol in 81 % isolated yield. [127] In another demonstrated example, a suspension of baker’s yeast (S. cerevisiae) (13 g) and d-glucose (10 g) in water (100 ml) was stirred at ca. 30 °C for 1 h, then a solution of Cyrene (10 mmol, 1.28 g) in water (10 ml) was added. The reaction mixture was stirred at ca. 30 °C. The reaction was monitored by silica-gel TLC until the disappearance of the starting Cyrene (ca. 24 h). Then ethanol (100 ml) was added, the precipitate was filtered off, washed with ethanol and the solution obtained was combined with the filtrate. The filtrate was evaporated in vacuo, extracted with diethyl ether (3 X 50 ml_), dried over anhydrous magnesium sulphate and evaporated in vacuo. The residue was purified by column chromatography using silica gel to get 0.82 g levoglucosanol in 63% isolated yield.

[128] In a prophetic example, sodium borohydride reduction in methanol, according to the method reported in J. Pecka et al Collect. Czech. Chem. Commun.1974, 39, 1192 and Pecka et al Collect. Czech. Chem. Commun. 1978, 43, 1720, is used to reduce Cyrene. Thus, sodium borohydride (NaBhU) (380 mg, 10 mmol) is added in portions to a solution of Cyrene (5 mmol, 640 mg) in dry methanol (25 ml_) over a period of 30 minutes at 0°C. The reaction mixture is stirred for 24 h at room temperature before dilution with water (25 ml_), and the product is extracted with ethyl acetate (3 x 25 ml_). The combined ethyl acetate layer is washed with water (3X25 ml_), brine (25 ml_) and dried over anhydrous Na2S04 before being evaporated under vacuum. The residue is purified by column chromatography to yield levoglucosanol.

[129] In another prophetic example, sodium borohydride (NaBhU) (380 mg, 10 mmol) is added in portions to a solution of Cyrene (5 mmol, 640 mg) in H2O (25 ml_) over a period of 30 minutes at 0°C. The reaction mixture is stirred for 24 h at 60°C before the product is extracted with ethyl acetate (2 x 25 ml_). The combined ethyl acetate layer is washed with water (3X25 ml_), brine (25 ml_) and dried over anhydrous Na2S04 before being evaporated under vacuum. The residue is purified by column chromatography to yield levoglucosanol.

[130] In another prophetic example, to a solution of Cyrene (5 mmol, 640 mg) in 25 ml_ dry CH2CI2 (-40 °C), diisobutylaluminium hydride (DIBALH) (1.1 equiv, 1.0 M in toluene) is added dropwise over 15 min and the reaction continued stirring for 3 h. A further amount of diisobutylaluminium hydride (DIBALH) (1.9 equiv) is added and the reaction continued to stir for further 3 h. MeOH is added to destroy the excess of reagent and the mixture is warmed to room temperature. The suspension is filtered over Celite and the solvent is evaporated before the crude reaction mixture is purified by chromatography to yield levoglucosanol.

[131] In another prophetic example, catalysed H2 hydrogenation, according to the method reported by Zanardi et al, Tetrahedron Letters 50 (2009) 999-1002, is used to reduce Cyrene. A solution of Cyrene (5 mmol, 640 mg) in 25 mL dry THF is hydrogenated with H2 for 3h at 500 psi in the presence of Pd/C (5%) at 100 °C. The reaction is filtered to remove catalyst and the filtrate is evaporated in vacuo. The residue is purified by column chromatography to yield levoglucosanol.

[132] In another prophetic example, a solution of Cyrene (5 mmol, 640 mg) in 25 mL dry ethyl acetate is hydrogenated with H2 for 3h at 500 psi in the presence of Raney Ni catalyst at 20 °C. The reaction is filtered to remove catalyst and the filtrate is evaporated in vacuo. The residue is purified by column chromatography to yield levoglucosanol.

[133] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.