Field of the Invention

The present invention relates in general to polymer coatings upon the surface of a substrate. In particular, the invention relates to polymer brush coatings and to a method of preparing the same.

Background of the Invention

The control of surface properties is often fundamental to many fields of research, and essential in many commercial technologies. In particular, it is often important to differentiate between the bulk properties of a material or device and the surface properties of that material or device. The bulk or substrate material will typically be employed to provide bulk properties suitable for the intended application, such as mechanical or refractive properties. However, in many applications the surface properties of the substrate material are not suitable or ideal for the intended application. Accordingly, it is often desired or required to mask the surface properties of the substrate.

For example, surface modification may be used to achieve a degree of control over the biological response to the material or device that can not otherwise be achieved by the properties of the bulk material itself.

One approach adopted for controlling surface properties of a substrate has been to employ polymer brush technology. A polymer brush is generally known in the art to comprise a plurality of polymer chains having one end that is directly or indirectly tethered to the surface of a substrate, with another end of the chain being free to extend from that surface.

The "brush" terminology stems from the tethered polymer chains being able to take on an orientation somewhat analogous to the bristles of a hair brush.

By providing at least the ends of the polymer chains that are free to extend from the substrate surface with a different molecular composition and/or structure to that of the substrate surface to which the chains are tethered, the polymer chains present as a "brush layer" (i.e. polymer layer) or "brush coating" (i.e. polymer coating) on the substrate surface that can mask the surface properties of the substrate.

Traditionally, polymer brushes have been prepared using a physisorption approach whereby a block copolymer is prepared such that one block strongly adsorbs to the substrate surface while a second block extends from the surface forming the brush layer. However, the physisorption technique can provide poor control over the brush density (i.e. the number of tethered polymer chains per unit surface area of the substrate surface). Furthermore, due to the physical nature by which the polymer chains are tethered to the substrate surface, the brush layer is generally thermally and solvolytically unstable.

In an attempt to overcome deficiencies of the physisorption approach, there has been considerable interest in developing techniques for covalently attaching polymer chains to surfaces. Research in this area gave rise to the so called "grafting to" and "grafting from" techniques.

In the "grafting to" technique, preformed polymer chains containing a suitable end or pendant functional group are reacted with appropriate reactive substrate surface functional groups. Although the resulting brush layer exhibits thermal and solvolytic stability due to covalent attachment of the polymer chains, the technique can be prone to achieving a low grafting density due to crowding of the substrate surface by the initial grafted polymer chains, which in turn hinders grafting of further polymer chains.

In contrast to the "grafting to" technique, the "grafting from" technique involves polymerisation from the substrate surface to "grow" the polymer chains that form the brush layer. In particular, the technique generally involves modifying the substrate surface so as to provide for suitable covalently bound or "immobilised" moieties that can function as reaction sites and promote polymerisation of monomers to form the polymer chains. Formation of the polymer chains in this way can provide for a high graft density. While proving useful in the formation of polymer brushes, the multi-step approach of first modifying the substrate surface to provide the moieties from which the polymer chains are to be derived, and then reacting these moieties with monomer so as to form the polymer chains can be cumbersome and time consuming. Furthermore, the intermediate surface modification steps required to immobilise these moieties often leads to subsequent interfacial adhesion problems, which can in turn promote undesirable delamination of the brush layer.

Depending upon the composition and form of the substrate, modification of its surface to enable polymer chains to be grafted thereto can be difficult or not viable at all.

An opportunity therefore remains to develop a new class of polymer brush coatings and methodology for preparing polymer brushes which address or ameliorate one or more disadvantages or shortcomings associated with existing polymer brushes and their methods of manufacture, or to at least provide a useful alternative to known polymer brushes and their method of manufacture.

Summary of the Invention

The present invention therefore provides a polymer brush in the form of an electrospun polymer fibre having grafted to its surface a plurality of living polymer chains that constitute the brush layer.

The present invention also provides a method of preparing a polymer brush, the method comprising: electrospinning a polymer composition so as to form an electrospun polymer fibre, wherein the polymer composition comprises polymer having one or more living polymerisation moieties covalently bound thereto, and wherein the resulting electrospun fibre presents a plurality of living polymerisation moieties on its surface; and polymerising one or more ethylenically unsaturated monomers under the control of living polymerisation moieties on the surface of the electrospun fibre so as to form living polymer chains that constitute the brush layer.

A "polymer brush" in accordance with the present invention is an electrospun polymer fibre having a plurality of living polymer chains grafted to the surface thereof. The polymer chains have one end that is covalently bound to the surface of the substrate (in the case of the present invention the fibre), with another end of the chain being free to extend from that surface. The grafted polymer chains therefore constitute the brush coating or function as a polymer layer or coating upon the surface of the electrospun polymer fibre.

This brush coating may be used as a platform for further surface modification including crosslinking, living polymerisation, non-living polymerisation, functionalisation, biofunctionalisation and for the incorporation of additional polymers which are either physically or covalently bound to the coating.

By "living polymer chain(s)" is meant a polymer chain derived from monomers that have been polymerised by a living polymerisation technique. Those skilled in the art will appreciate that "living polymerisation" is a form of addition polymerisation whereby chain growth propagates with essentially no chain transfer and essentially no termination that give rise to dead polymer chains. By a "dead polymer chain" is meant one that can not undergo further addition of monomers.

In a living polymerisation, typically all polymer chains are initiated at the start of the polymerisation with minimal new chains being initiated in latter stages of the polymerisation. After this initiation process, all the polymer chains in effect grow at the same rate. Characteristics and properties of a living polymerisation generally include (i) the molecular weight of the polymer increases with conversion, (ii) there is a narrow distribution of polymer chain lengths (i.e. they are of similar molecular weight), and (iii) additional monomers can be added to the polymer chain to create block co-polymer structures. Thus living polymerisation enables excellent control over molecular weight, polymer chain architecture and polydispersity of the resulting polymer that can not be achieved with non-living polymerisation methods. Through the ability to control the composition, architecture and molecular weight of the grafted living polymer chains, surface properties presented by polymer brushes in accordance with the invention can advantageously be tailored for a desired application. For example, the brushes may provide a controlled biological response by controlling the chemical and physical nature of the polymer chains.

The combination of being able to control the nature of the brush layer and having this brush layer grafted to the surface of electrospun polymer fibres, is believed to provide for a unique polymer "bottle brush" material that may be fabricated into an array of products. For example, the polymer brush may be used in textile manufacturing, to prepare scaffolds for cell culture, bioreactors or tissue engineering, as separation materials, as absorbent materials, as scaffolds for catalysis, and as scaffolds to immobilise pharmaceutical compounds or biological molecules.

In one embodiment, the polymer brush in accordance with the invention is provided in the form of a scaffold for cell culture, bioreactors or tissue engineering, a separation material, an absorbent material, a scaffold for catalysis, and a scaffold for immobilising pharmaceutical compounds or biological molecules.

According to the method of the invention, the electrospun fibre as formed presents living polymerisation moieties on its surface and thereby avoids the need to modify the fibre surface in preparation for the grafting step. In other words, the living polymerisation moieties on the surface of the fibre may be used without further modification to control the polymerisation of one or more ethylenically unsaturated monomers so as to form the brush layer on the surface of the fibre.

The present invention therefore also provides an electrospun polymer fibre for use in the manufacture of polymer brushes, the fibre presenting on its surface a plurality of living polymerisation moieties that are covalently bound to polymer that forms the fibre. The present invention further provides a method of preparing an electrospun polymer fibre for use in the manufacture of polymer brushes, the method comprising: electrospinning a polymer composition so as to form an electrospun polymer fibre, wherein the polymer composition comprises polymer having one or more living polymerisation moieties covalently bound thereto, and wherein the resulting electrospun fibre presents a plurality of living polymerisation moieties at its surface.

Through control of the concentration of the living polymerisation moieties in the polymer composition and/or the electrospinning process conditions, the density of living polymerisation moieties per unit surface area of the fibre can be controlled/varied. This in turn enables the density of polymer chains formed under the control of the living polymerisation moieties to be controlled/varied. Accordingly, the methods of the invention provide an efficient and effective means of preparing polymer brushes with a high degree of control.

Further aspects of the invention appear below in the detailed description of the invention.

Brief Description of the Drawings

The invention will also be described herein with reference to the following non-limiting drawings in which:

Figure 1 illustrates high resolution C Is XPS spectra obtained from the surface of UV grafted polystyrene ( — ) and polystyrene blended with poly(acrylic acid-co-diethyl- dithiocarbamic acid 4-vinyl-benyl ester) copolymer, electrospun at 20 kV grafted with iniferter spun at 20 ( — ) and 30 ( ) kV according to Example 1.

Figure 2 illustrates high resolution C 1 s XPS spectra obtained from the surface of UV grafted acrylamide on polystyrene ( — ) and polystyrene blended with poly(styrene-co- diethyl-dithiocarbamic acid 4-vinyl-phenyl ester) ( ) electrospun membranes according to Example 2. Figure 3 illustrates high resolution C Is XPS spectra obtained from the surface of UV grafted glucoside on polystyrene ( — ) and polystyrene blended with poly(styrene-co- diethyl-dithiocarbamic acid 4-vinyl-phenyl ester) ( ) electrospun membranes according to Example 2.

Figure 4 illustrates high resolution C Is XPS spectra obtained from the surface of polystyrene (- — ), acrylamide grafted membranes produced at 20 ( — ) and 30 ( ) kV according to Example 3.

Figure 5 illustrates high resolution C Is XPS spectra obtained from the surface of HEA grafted membranes: polystyrene ( — ), and polystyrene blended with a copolymer containing RAFT moieties ( — ) according to Example 4.

Figure 6 illustrates high resolution C Is XPS spectra obtained from the surface of polystyrene ( — ) and membranes containing the RAFT moiety grafted with acrylamide (- - -) according to Example 4.

Figure 7 illustrates high resolution C Is XPS spectra obtained from the surface of HEA grafted membranes: polystyrene ( — ), and poly(styrene-co-butyl 4-vinylbenzyl trithiocarbonate) ( — ) according to Example 5.

Figure 8 illustrates a high resolution C Is XPS spectra obtained from the surface of acrylamide grafted membranes: PS ( — ) and poly(styrene-co -butyl 4-vinylbenzyl trithiocarbonate) ( ) according to Example 5.

Figure 9: illustrates high resolution C Is XPS spectra obtained from the surface of AAm and PEGMA grafted on membranes: untreated PS membranes with RAFT moieties ( — ),

PS with RAFT grafted with AAm ( ), and PS with RAFT grafted with PEGMA ( ) according to Example 6. Figure 10 illustrates the comparison of HSA adsorption on membranes before and after RAFT-mediated grafting according to Example 7.

Figure 11 illustrates high resolution C Is XPS spectra obtained from the surface of grafted fluorinated membranes: untreated PS membranes with fluorinated RAFT moieties ( — ),

PS coated with polyacrylamide ( — ), and PS coated with polyacrylic acid ( ) according to Example 8.

Figure 12 illustrates high resolution C Is XPS spectra obtained from the surface of grafted fluorinated membranes: untreated PS membranes with fluorinated RAFT moieties ( — ),

PS coated with polyNIPAAm ( ), and PS coated with poly PEGMA ( ) according to

Example 8.

Figure 13 illustrates high resolution C Is XPS spectra obtained from the surface of poly(styrene-co-butyl 4-vinylbenzyl chloride) electrospun fibres with curvefits pertaining the underlying carbon chemistry according to Example 9.

Figure 14 illustrates high resolution CIs XPS spectra obtained from PEG grafted membranes of poly(styrene-co-butyl 4-vinylbenzyl chloride). PEGMA concentration during polymerisation was varied from 0.05M ( — ) and 0.5M ( — ) according to Example 9.

Figure 15 illustrates the comparison of HSA adsorption on membranes before and after ATRP -mediate grafting using different concentrations of PEGMA according to Example 9.

Detailed Description of the Invention

Polymer brushes in accordance with the invention have as part of their structure an electrospun polymer fibre. By "electrospun polymer fibre" is meant a polymer fibre that has been formed using an electrospinning process. As used herein, the term

"electrospinning", also known as "electrostatic spinning" is intended to mean the process of forming polymer fibres by expressing a liquid polymer composition through a capillary, syringe needle or similar orifice under the influence of an electrostatic field and collecting the resulting fibres on a target.

The process of electro spinning is well known and generally involves creating an electrical field at the surface of a conducting fluid which could be a polymer solution or melt. The fluid is contained within a vessel (sometimes referred to as a spinneret) having an appropriate outlet through which the polymer fluid may be extruded to form a droplet. The droplet, under the influence of the applied electric field, takes on a cone shape which is commonly referred to as a Taylor cone. Once the applied electric field overcomes the surface tension of the drop, a jet forms, which elongates as it is attracted to a suitably located, oppositely charged or grounded collector plate or target area. As the jet of liquid polymer composition elongates and travels to the collector plate, it transitions from a liquid to a solid thereby forming the fibre.

The transformation from a liquid composition to a solid fibre will occur by different mechanisms depending upon the nature of the liquid polymer composition. For example, the liquid polymer composition may be a polymer melt which solidifies upon cooling to form the fibres. The liquid composition might comprise solvent which evaporates upon electrospinning to form the fibres, The liquid polymer composition might also be of a type that undergoes a curing reaction upon electrospinning to form the fibres. The dimensions of the resultant fibres depend on both the material properties such as molecular weight, molecular weight distribution, concentration, surface tension as well as processing conditions such as field strength, feed rate and electrode geometries. Electrospun polymer fibres used in accordance with the present invention can advantageously be prepared using conventional electrospinning techniques and equipment.

There is no particular limitation on the physical dimensions of the electrospun polymer fibres, with such dimensions generally being selected to suit the intended application of the resulting polymer brush. Electrospinning is particularly well suited to forming electrospun microfibres and nanofibres, with diameters of the fibres typically ranging from about 3 nm to about 25 microns. Generally, the electrospun polymer fibres associated with the present invention will have an average diameter of no more than about 25 microns, for example no more than about 5 microns. In some applications, it may be desirable for the fibres to have an average diameter of no more than about 1 micron, for example ranging from about 3 nm to about 1000 nm. The fibre diameters referred to herein are those of the electrospun polymer fibre per se (i.e. not the fibre plus the grafted polymer chians) as determined using scanning electron microscopy (SEM).

Electrospinning is a convenient technique for preparing nano-scale diameter polymer fibres which are particularly useful in biomedical and industrial applications due to their intrinsically high surface area, high porosity (when provided as a collection of fibres), and their dimensional similarities to components within the extracellular matrix. In particular, there is increasing interest in using electrospun nanofibres in applications such as biosensors, protective clothing and for generating extracellular microenvironments for tissue engineering and laboratory cell cultureware.

For a given application, the surface properties presented by the electrospun fibres will generally be an important characteristic. For example, the fibres might be required to elicit a biological response such as bioadhesion or biorepulsion and to attract or repel targeted biomolecules and cells. However, the surface of electrospun polymer fibres generally needs to be modified so that the fibres present the desired surface characteristics. Such modification to date has proven cumbersome if not difficult.

In accordance with the method of the invention, electrospinning is conducted using a unique polymer composition which comprises polymer having one or more living polymerisation moieties covalently bound thereto. As used herein, a "living polymerisation moiety(ies)" is intended to mean a moiety that can participate in and control the living polymerisation of one or more ethylenically unsaturated monomers so as to form a living polymer chain. Living polymerisation moieties suitable for use in accordance with the invention include, but are not limited to, those which promote living polymerisation techniques selected from ionic polymerisation and controlled radial polymerisation (CRP). Examples of CRP include, but are not limited to, iniferter polymerisation, stable free radical mediated polymerisation (SFRP), atom transfer radical polymerisation (ATRP), and reversible addition fragmentation chain transfer (RAFT) polymerisation.

Living ionic polymerisation is a form of addition polymerisation whereby the kinetic-chain carriers are ions or ion pairs. The polymerisation proceeds via anionic or cationic kinetic- chain carriers. In other words, the propagating species will either carry a negative or positive charge, and as such there will also be an associated counter cation or counter anion, respectively. For example, in the case of anionic polymerisation, the living polymerisation moiety might be represented as -FM , where I represents an organo-anion (e.g. an optionally substituted alkyl anion) and M represents an associated countercation, or in the case of living cationic polymerisation, the living polymerisation moiety might be represented as -I ⁺ M ^' , where I represents an organo-cation (e.g. an optionally substituted alkyl cation) and M represents an associated counteranion. Suitable moieties for conducting anionic and cationic living polymerisation are well known to those skilled in the art.

In an embodiment of the invention, the living polymerisation moiety promotes CRP, or in other words the living polymerisation moiety is a CRP moiety.

Iniferter polymerisation is a well known form of CRP, and is generally understood to proceed by a mechanism illustrated below in Scheme 1. a) AB A» + ^» B

b) A» + M I WWW * d) A*"^* + AB A^B + *A β) A-vww* + βwwA β -f* • wwwΑ f ) A' ^ΛΛ/WW> • -J" • WWW ¹ A A< ^w *A

Scheme 1: General mechanism of controlled radical polymerisation with iniferters.

With reference to Scheme 1, the iniferter AB dissociates chemically, thermally or photochemically to produce a reactive radical species A and generally a relatively stable radical species B (for symmetrical iniferters the radical species B will be the same as the radical species A) (step a). The radical species A can initiate polymerisation of monomer

M (in step b) and may be deactivated by coupling with radical species B (in step c).

Transfer to the iniferter (in step d) and/or transfer to dormant polymer (in step e) followed by termination (in step f) characterise iniferter chemistry.

As a living polymerisation moiety used in accordance with the present invention, an iniferter moiety may therefore be represented as -AB or -BA, where AB or BA can dissociate chemically, thermally or photochemically as illustrated above in Scheme 1. In other words, the iniferter moiety -AB or -BA will be covalently bound to polymer that forms at least a part of the polymer composition which is subjected to electrospinning to form the electrospun polymer fibre. Suitable moieties for conducting iniferter polymerisation are well known to those skilled in the art, and include, but are not limited to, dithiocarbonate, disulphide, and thiuram disulphide moieties. In a further embodiment of the invention, the living polymerisation moiety promotes SFRP, or in other words the living polymerisation moiety is a SFRP moiety. As suggested by its name, this mode of radical polymerisation involves the generation of a stable radical species as illustrated below in Scheme 2.

CD . C + -D

M

Scheme 2: General mechanism of controlled radical polymerisation with stable free radical mediated polymerisation.

With reference to Scheme 2, SFRP moiety CD dissociates to produce an active radical species C and a stable radical species D. The active radical species C reacts with monomer M, which resulting propagating chain may recombine with the stable radical species D. Unlike iniferter moieties, SFRP moieties do not provide for a transfer step.

As a living polymerisation moiety used in accordance with the present invention, an SFRP moiety may therefore be represented as -CD or -DC, where CD or DC can dissociate chemically, thermally or photochemically as illustrated above in Scheme 2. In other words, the SFRP moiety -CD or -DC will be covalently bound to polymer that forms at least a part of the polymer composition which is subjected to electrospinning to form the electrospun polymer fibre. Suitable moieties for conducting SFRP are well known to those skilled in the art, and include, but are not limited to, moieties capable of generating phenoxy and nitroxy radicals. Where the moiety generates a nitroxy radical, the polymerisation technique is more commonly known as nitroxide mediated polymerisation (NMP). Examples of SFRP moieties capable of generating phenoxy radicals include those comprising a phenoxy group substituted in the 2 and 6 positions by bulky groups such as tert-alkyl (e.g. t-butyl), phenyl or dimethylbenzyl, and optionally substituted at the 4 position by an alkyl, alkyloxy, aryl, or aryloxy group or by a heteroatom containing group (e.g. S, N or O) such dimethylamino or diphenylamino group. Thiophenoxy analogues of such phenoxy containing moieties are also contemplated.

SFRP moieties capable of generating nitroxy radicals include those comprising the

1 0 I T 1 0 substituent R R N-O-, where R and R are tertiary alkyl groups, or where R and R together with the N atom form a cyclic structure, preferably having tertiary branching at the positions α to the N atom. Examples of such nitroxy substituents include. 2,2,5,5- tetraalkylpyrrolidinoxyl, as well as those in which the 5-membered hetrocycle ring is fused to an alicyclic or aromatic ring, hindered aliphatic dialkylaminoxyl and iminoxyl substituents. A common nitroxy substituent employed in SFRP is 2,2,6,6-tetramethyl-l- piperidinyloxy.

In another embodiment of the invention, the living polymerisation moiety promotes ATRP, or in other words the living polymerisation moiety is an ATRP moiety. ATRP generally employs a transition metal catalyst to reversibly deactivate a propagating radical by transfer of a transferable atom or group such as a halogen atom to the propagating polymer chain, thereby reducing the oxidation state of the metal catalyst as illustrated below in Scheme 3. E-X + M _t ⁿ - . E. + M _t ⁿ X

M

EvAΛo χ + ]y[ _t n , + M _t ⁿ X

Scheme 3: General mechanism of controlled radical polymerisation with atom transfer radical polymerisation.

With reference to Scheme 3, a transferable group or atom (X , e.g. halide, hydroxyl, C ₁ -C ₆ - alkoxy, cyano, cyanato, thiocyanato or azido) is transferred from the organic compound (E) (which may represent the polymer) to a transition metal catalyst (M _t , e.g. copper, iron, gold, silver, mercury, palladium, platinum, cobalt, manganese, ruthenium, molybdenum, niobium, or zinc) having oxidation number (n), upon which a radical species is formed that initiates polymerisation with monomer (M). As part of this process, the metal complex is oxidised (M _t ⁿ⁺¹ X). A similar reaction sequence is then established between the propagating polymer chain and the dormant X end-capped polymer chains.

As a living polymerisation moiety used in accordance with the present invention, an ATRP moiety may therefore be represented as -EX, where E is an organic group (e.g. optionally substituted alkyl, optionally substituted aryl, optionally substituted alkylaryl, or the polymer chain) and X is an atom or group that can participate in a redox cycle with a transition metal catalyst to reversibly generate a radical species and the oxidised metal catalyst as illustrated above in Scheme 3. In other words, the ATRP moiety -EX or simply -X will be covalently bound to polymer that forms at least a part of the polymer composition which is subjected to electrospinning to form the electrospun polymer fibre.

Although ATRP requires the presence of a transition metal catalyst to proceed, it is not intended that the transition metal catalyst form part of the living polymerisation moiety used in accordance with the invention.

In a further embodiment of the invention, the living polymerisation moiety promotes RAFT polymerisation, or in other words the living polymerisation moiety is a RAFT moiety. RAFT polymerisation is well known in the art and is believed to operate through the mechanism outlined below in Scheme 4.

a) b)

Scheme 4: General mechanism of controlled radical polymerisation with reversible addition fragmentation chain transfer polymerisation.

With reference to Scheme 4, RAFT polymerisation is believed to proceed through initial reaction sequence (a) that involves reaction of a RAFT moiety (1) with a propagating radical. The labile intermediate radical species (2) that is formed fragments to form a temporarily deactivated dormant polymer species (3) together a radical (R) derived from the RAFT moiety. This radical can then promote polymerisation of monomer (M), thereby reinitiating polymerisation. The propagating polymer chain can then react with the dormant polymer species (3) to promote the reaction sequence (b) that is similar to reaction sequence (a). Thus, a labile intermediate radical (4) is formed and subsequently fragments to form again a dormant polymer species together with a radical which is capable of further chain growth.

RAFT moieties suitable for use in accordance with the invention comprise a thiocarbonylthio group (which is a divalent moiety represented by: -C(S)S-). Examples of RAFT moieties are described in Moad G.; Rizzardo E.; Thang S H. Polymer 2008, 49, 1079-1131 (the contents of which are incorporated herein by reference) and include xanthates, dithioesters, dithiocarbonates, dithiocarbanates and trithiocarbonates.

A RAFT moiety suitable for use in accordance with the invention may be represented by general formula (1) shown in Scheme 4 above, where the Z or R groups represent the polymer to which the moiety is covalently bound, or where the Z or R groups are themselves covalently bound to the polymer. Where the Z or R groups are not the polymer, they are selected from groups known in the art to enable the moiety to undergo RAFT polymerisation.

For example, the Z group may be selected from fluorine, chlorine, bromine, iodine, alkyl, aryl, acyl, amino, carbocyclyl, heterocyclyl, heteroaryl, alkyloxy, aryloxy, acyloxy, acylamino, carbocyclyloxy, heterocyclyloxy, heteroaryloxy, alkylthio, arylthio, acylthio, carbocyclylthio, heterocyclylthio, heteroarylthio, alkylaryl, alkylacyl, alkylcarbocyclyl, alkylheterocyclyl, alkylheteroaryl, alkyloxyalkyl, aryloxyalkyl, alkylacyloxy, alkylcarbocyclyloxy, alkylheterocyclyloxy, alkylheteroaryloxy, alkylthioalkyl, arylthioalkyl, alkylacylthio, alkylcarbocyclylthio, alkylheterocyclylthio, alkylheteroarylthio, alkylarylalkyl, alkylacylalkyl, arylalkylaryl, arylacylaryl, arylacyl, arylcarbocyclyl, arylheterocyclyl, arylheteroaryl, aryloxyaryl, arylacyloxy, arylcarbocyclyloxy, arylheterocyclyloxy, arylheteroaryloxy, alkylthioaryl, arylthioaryl, fluoroalkylthio, perfluoroalkylthio, arylacylthio, arylcarbocyclylthio, arylheterocyclylthio, arylheteroarylthio, dialkyloxy- , diheterocyclyloxy- or diaryloxy- phosphinyl, dialkyl-, diheterocyclyl- or diaryl- phosphinyl, and cyano (i.e. -CN).

The Z group might also be selected from fluorine, chlorine, C ₁ -C ₁₈ alkyl, C ₆ -C ₁₈ aryl, C ₁ - C ₁₈ acyl, amino, C ₃ -C] ₈ carbocyclyl, C ₂ -C ₁₈ heterocyclyl, C ₃ -C ₁₈ heteroaryl, C ₁ -C ₁₈ alkyloxy, C ₆ -Ci ₈ aryloxy, C _J -C _I8 acyloxy, C ₃ -Ci ₈ carbocyclyloxy, C ₂ -Ci ₈ heterocyclyloxy, C ₃ -Ci ₈ heteroaryloxy, Ci-Ci ₈ alkylthio, C ₆ -Ci ₈ arylthio, Cj-Ci ₈ acylthio, C ₃ -Ci ₈ carbocyclylthio, C ₂ -Ci ₈ heterocyclylthio, C ₃ -Ci ₈ heteroarylthio, C ₇ -C ₂₄ alkylaryl, C ₂ -Ci ₈ alkylacyl, C ₄ -Ci ₈ alkylcarbocyclyl, C ₃ -Ci ₈ alkylheterocyclyl, C ₄ -Ci ₈ alkylheteroaryl, C ₂ - Ci ₈ alkyloxyalkyl, C ₁ -C ₂ ^ aryloxyalkyl, C ₂ -Ci ₈ alkylacyloxy, C ₄ -Ci ₈ alkylcarbocyclyloxy, C ₃ -Ci ₈ alkylheterocyclyloxy, C ₄ -Ci ₈ alkylheteroaryloxy, C ₂ -Ci ₈ alkylthioalkyl, C ₇ -C ₂₄ arylthioalkyl, C ₂ -Cj ₈ alkylacylthio, C ₄ -Cj ₈ alkylcarbocyclylthio, C ₃ -C ₁₈ alkylheterocyclylthio, C ₄ -Ci ₈ alkylheteroarylthio, C ₈ -C ₂₄ alkylarylalkyl, C ₃ -Ci ₈ alkylacylalkyl, Cj ₃ -C ₂₄ arylalkylaryl, Cj ₃ -C ₂₄ arylacylaryL C ₇ -Cj ₈ arylacyl, Cp-Cj ₈ arylcarbocyclyl, C ₈ -Cj ₈ arylheterocyclyl, C ₉ -C ₁₈ arylheteroaryl, C) ₂ -C ₂₄ aryloxyaryl, C ₇ - Cj ₈ arylacyloxy, C ₉ -Ci ₈ arylcarbocyclyloxy,, C ₈ -Ci ₈ arylheterocyclyloxy, C ₉ -Ci ₈ arylheteroaryloxy, C ₇ -Ci ₈ alkylthioaryl, C] ₂ -C ₂₄ arylthioaryl, C ₇ -C ₁₈ arylacylthio, C ₉ -Cj ₈ arylcarbocyclylthio, C ₈ -Ci ₈ arylheterocyclylthio, C ₉ -C ₁₈ arylheteroarylthio, dialkyloxy- , diheterocyclyloxy- or diaryloxy- phosphinyl (i.e. -P(=O)OR ^k ₂ ), dialkyl-, diheterocyclyl- or diaryl- phosphinyl (i.e. -P(=O)R ^k 2), where R ^k is selected from optionally substituted Ci-Ci ₈ alkyl, optionally substituted C ₆ -Cj ₈ aryl, optionally substituted C ₂ -Cj ₈ heterocyclyl, and optionally substituted C ₇ -C ₂₄ alkylaryl, and cyano (i.e. -CN).

For example, the R group may be selected from alkyl, alkenyl, alkynyl, aryl, acyl, carbocyclyl, heterocyclyl, heteroaryl, alkyloxy, alkenyloxy, alkynyloxy, aryloxy, acyloxy, carbocyclyloxy, heterocyclyloxy, heteroaryloxy, alkylthio, alkenylthio, alkynylthio, arylthio, acylthio, carbocyclylthio, heterocyclylthio, heteroarylthio, alkylalkenyl, alkylalkynyl, alkylaryl, alkylacyl, alkylcarbocyclyl, alkylheterocyclyl, alkylheteroaryl, alkyloxyalkyl, alkenyloxyalkyl, alkynyloxyalkyl, aryloxyalkyl, alkylacyloxy, alkylcarbocyclyloxy, alkylheterocyclyloxy, alkylheteroaryloxy, alkylthioallcyl, alkenylthioalkyl, alkynylthioalkyl, arylthioalkyl, alkylacylthio, alkylcarbocyclylthio, alkylheterocyclylthio, alkylheteroarylthio, alkylalkenylalkyl, alkylalkynylalkyl, alkylarylalkyl, alkylacylalkyl, arylalkylaryl, alkenylarylalkyl, alkylarylalkenyl, arylalkenylaryl, arylalkynylaryl, arylacylaryl, arylacyl, arylcarbocyclyl, arylheterocyclyl, arylheteroaryl, alkenyloxyaryl, alkynyloxyaryl, aryloxyaryl, arylacyloxy, arylcarbόcyclyloxy, arylheterocyclyloxy, arylheteroaryloxy, alkylthioaryl, alkenylthioaryl, alkynylthioaryl, arylthioaryl, arylacylthio, arylcarbocyclylthio, arylheterocyclylthio, and ary lheteroarylthio .

The R group might also be selected from C ₁ -Cj ₈ alkyl, C ₂ -CJ ₈ alkenyl, C ₂ -Cj ₈ alkynyl, C ₆ - Cj ₈ aryl, C ₁ -Ci ₈ acyl, C ₃ -Cj ₈ carbocyclyl, C ₂ -CiS heterocyclyl, C ₃ -Cig heteroaryl, Ci-C ₁₈ alkyloxy, C ₂ -Ci ₈ alkenyloxy, C ₂ -Ci ₈ alkynyloxy, C ₆ -Ci ₈ aryloxy, C _J -C _J8 acyloxy, C ₃ -Ci ₈ carbocyclyloxy, C ₂ -Ci ₈ heterocyclyloxy, C ₃ -Ci ₈ heteroaryloxy, C _I -C _{J 8} alkylthio, C ₂ -C] ₈ alkenylthio, C ₂ -Ci ₈ alkynylthio, C ₆ -Ci ₈ arylthio, Ci-Ci ₈ acylthio, C ₃ -CJ ₈ carbocyclylthio, C ₂ -C ₁₈ heterocyclylthio, C ₃ -Cj _S heteroarylthio, C ₃ -C _{J 8} alkylalkenyl, C ₃ -C _J8 alkylalkynyl, C ₇ -C ₂₄ alkylaryl, C ₂ -Ci ₈ alkylacyl, C ₄ -Cj ₈ alkylcarbocyclyl, C ₃ -Ci ₈ alkylheterocyclyl, C ₄ - C] ₈ alkylheteroaryl, C ₂ -Cj ₈ alkyloxyalkyl, C ₃ -Cj ₈ alkenyloxyalkyl, C ₃ -Ci ₈ alkynyloxyalkyl, C ₇ -C ₂₄ aryloxyalkyl, C ₂ -Ci ₈ alkylacyloxy, C ₄ -Ci ₈ alkylcarbocyclyloxy, C ₃ -Ci ₈ alkylheterocyclyloxy, C ₄ -C ₁₈ alkylheteroaryloxy, C ₂ -Ci ₈ alkylthioalkyl, C ₃ -Ci ₈ alkenylthioalkyl, C ₃ -Ci ₈ alkynylthioalkyl, C ₇ -C ₂₄ arylthioalkyl, C ₂ -Ci ₈ alkylacylthio, C ₄ - Cj ₈ alkylcarbocyclylthio, C ₃ -Ci ₈ alkylheterocyclylthio, C ₄ -C ₁₈ alkylheteroarylthio, C ₄ -Cj ₈ alkylalkenylalkyl, C ₄ -Cj ₈ alkylalkynylalkyl, C ₈ -C ₂₄ alkylarylalkyl, C ₃ -Cj ₈ alkylacylalkyl, Cj ₃ -C ₂₄ arylalkylaryl, Cj ₄ -C ₂₄ arylalkenylaryl, Cj ₄ -C ₂₄ arylalkynylaryl, Cj ₃ -C ₂₄ arylacylaryl, C ₇ -Ci ₈ arylacyl, C ₉ -Ci ₈ arylcarbocyclyl, C ₈ -Ci ₈ arylheterpcyclyl, C ₉ -Ci ₈ arylheteroaryl, C ₈ -Ci ₈ alkenyloxyaryl, C ₈ -Ci ₈ alkynyloxyaryl, Cj ₂ -C ₂₄ aryloxyaryl, C ₇ -Ci ₈ arylacyloxy, C ₉ -Ci ₈ arylcarbocyclyloxy, C ₈ -C) ₈ arylheterocyclyloxy, C ₉ -Ci ₈ arylheteroaryloxy, C ₇ -Ci ₈ alkylthioaryl, C ₈ -Ci ₈ alkenylthioaryl, C ₈ -Ci ₈ alkynylthioaryl, Ci ₂ -C ₂₄ arylthioaryl, C ₇ -CJ ₈ arylacylthio, C ₉ -Ci ₈ arylcarbocyclylthio, C ₈ -Ci ₈ arylheterocyclylthio, and C ₉ -C] ₈ ary lheteroarylthio.

In the lists above defining groups from which Z and R may be selected, each alkyl, aryl, carbocyclyl, heteroaryl, and heterocyclyl moiety may be optionally substituted. For avoidance of any doubt where a given Z and R group contains two or more of such moieties (e.g. alkylaryl), each of such moieties may be optionally substituted with one, two, three or more optional substituents as herein defined.

Those skilled in the art will appreciate that depending upon the type of living polymerisation moiety employed, the moiety may be covalently bound to the polymer in a manner that will promote "grafting from" or "grafting to" living polymerisation. For example, if a RAFT moiety is employed, the Z group of formula (1) in Scheme 4 above may represent the polymer or it may be covalently bound to the polymer, in which case the moiety will provide for "grafting to" polymerisation. Where the R group in general formula (1) in Scheme 4 is the polymer or is covalently bound to the polymer, the living polymerisation moiety will provide for "grafting from" polymerisation.

For the reasons outlined above, it will generally be preferred that the living polymerisation moieties are covalently bound to the polymer so as to provide for "grafting from" polymerisation. In other words, it is preferred that propagating radicals that give rise to the living polymer chains remain covalently attached to the surface of the electrospun fibre.

There is no particular limitation as to the manner in which the polymer to be electrospun having one or more living polymerisation moieties covalently bound thereto is prepared.

For example, the polymer may be formed through the living polymerisation of one or more ethylenically unsaturated monomers. In that case, the living polymerisation moiety may form an end group of the so formed polymer chain as dictated by the living polymerisation process employed. As a specific example, one or more ethylenically unsaturated monomers may be polymerised under the control of a RAFT agent so as to form a living polymer chain end-capped with a RAFT moiety. The RAFT agent used may of course present multiple -C(S)S- groups that may control multiple sites of polymerisation to form a multi-arm polymer such as a star polymer which in effect has multiple living polymer chains each end-capped with a RAFT moiety. Polymer formed in this manner may be used as the sole polymer in the polymer composition that is subjected to electrospinning in accordance with the method of the invention.

However, to provide the desired concentration of living polymerisation moieties in the polymer composition, it may be necessary to reduce the molecular weight of the polymer to a point where electrospinning of fibres becomes problematic due to a drop in viscosity. In that case, it may be desirable to include in the polymer composition one or more other polymers having a higher molecular weight to in effect increase the average molecular weight of the entire polymer composition. The one or more other polymers may or may not have a living polymerisation moieties covalently bound thereto.

The polymer to be electrospun having one or more living polymerisation moieties covalently bound thereto may also be formed by polymerising monomers having living polymerisation moieties covalently bound thereto. For example, the monomer may be of general formula (I): LPM-Q-CH=CH ₂ , where LPM is the living polymerisation moiety and Q is a divalent organic group that couples the LPM to the vinyl moiety. In some embodiments, Q may form part of the LPM ₅ in which case general formula (I) may be represented as general formula (Ia): LPM-CH=CH ₂ . In one embodiement, the LPM of general formulae (I) and (Ia) is a CRP moiety. For convenience, general formula (I) or (Ia) may hereinafter simply be referred to as a vinyl substituted living polymerisation moiety.

The substituent Q in general formula (I) can generally be selected from any divalent organic substituent provided the monomer can still be appropriately polymerised to form the polymer. Generally, Q is a divalent form of a group selected from alkyl, alkenyl, alkynyl, aryl, acyl, carbocyclyl, heterocyclyl, heteroaryl, alkyloxy, alkenyloxy, alkynyloxy, aryloxy, acyloxy, carbocyclyloxy, heterocyclyloxy, heteroaryl oxy, alkylthio, alkenylthio, alkynylthio, arylthio, acylthio, carbocyclylthio, heterocyclylthio, heteroarylthio, alkylalkenyl, alkylalkynyl, alkylaryl, alkylacyl, alkylcarbocyclyl, alkylheterocyclyl, alkylheteroaryl, alkyloxyalkyl, alkenyloxyalkyl, alkynyloxyalkyl, aryloxyalkyl, alkylacyloxy, alkylcarbocyclyloxy, alkylheterocyclyloxy, alkylheteroaryloxy, alkylthioalkyl, alkenylthioalkyl, alkynylthioalkyl, arylthioalkyl, alkylacylthio, alkylcarbocyclylthio, alkylheterocyclylthio, alkylheteroarylthio, alkylalkenylalkyl, alkylalkynylalkyl, alkylarylalkyl, alkylacylalkyl, arylalkylaryl, arylalkenylaryl, arylalkynylaryl, arylacylaryl, arylacyl, arylcarbocyclyl, arylheterocyclyl, arylheteroaryl, alkenyloxyaryl, alkynyloxyaryl, aryloxyaryl, arylacyloxy, arylcarbocyclyloxy, arylheterocyclyloxy, arylheteroaryloxy, alkylthioaryl, alkenylthioaryl, alkynylthioaryl, arylthioaryl, arylacylthio, arylcarbocyclylthio, arylheterocyclylthio, and arylheteroarylthio.

More specifically, X may be a divalent form of any of the groups selected from Ci-C ₁₈ alkyl, C ₂ -Ci ₈ alkenyl, C ₂ -C] ₈ alkynyl, C ₆ -C] ₈ aryl, Cj-C ₁₈ acyl, C ₃ -C ₁₈ carbocyclyl, C ₂ -C] ₈ heterocyclyl, C ₃ -C] ₈ heteroaryl, Cj-Ci ₈ alkyloxy, C ₂ -C] ₈ alkenyloxy, C ₂ -Cj ₈ alkynyloxy, C _ό -Cig aryloxy, Cj-Ci ₈ acyloxy, C ₃ -C] ₈ carbocyclyloxy, C ₂ -C] ₈ heterocyclyloxy, C ₃ -C ₁₈ heteroaryloxy, C]-Cj ₈ alkylthio, C ₂ -C ₁₈ alkenyltliio, C ₂ -C ₁₈ alkynylthio, C ₆ -C ₁₈ arylthio, Ci-Cjs acylthio, C ₃ -CiS carbocyclylthio, C ₂ -Cj _S heterocyclylthio, C ₃ -CjS heteroarylthio, C ₃ - Cj ₈ alkylalkenyl, C ₃ -Cj ₈ alkylalkynyl, C ₇ -C ₂₄ alkylaryl, C ₂ -Cj ₈ alkylacyl, C ₄ -Cj ₈ alkylcarbocyclyl, C ₃ -CjS alkylheterocyclyl, C ₄ -Cj ₈ alkylheteroaryl, C ₂ -Cj ₈ alkyloxyalkyl, C ₃ -Cj ₈ alkenyloxyalkyl, C ₃ -Cj ₈ alkynyloxyalkyl, C ₇ -C ₂₄ aryloxyalkyl, C ₂ -C ₁₈ alkylacyloxy, C ₄ -Cj ₈ alkylcarbocyclyloxy, C ₃ -Cj ₈ alkylheterocyclyloxy, C ₄ -Ci ₈ alkylheteroaryloxy, C ₂ - Cis alkylthioalkyl, C ₃ -Cj ₈ alkenylthioalkyl, C ₃ -Cj ₈ alkynylthioalkyl, C ₇ -C ₂₄ arylthioalkyl, C ₂ -Ci ₈ alkylacylthio, C ₄ -Ci ₈ alkylcarbocyclylthio, C ₃ -Cj ₈ alkylheterocyclylthio, C ₄ -Ci ₈ alkylheteroarylthio, C ₄ -Cj ₈ alkylalkenylalkyl, C ₄ -Ci ₈ alkylalkynylalkyl, C ₈ -C ₂₄ alkylarylalkyl, C ₃ -Cj ₈ alkylacylalkyl, Cj ₃ -C ₂₄ arylalkylaryl, Ci ₄ -C ₂₄ arylalkenylaryl, Ci ₄ - C ₂₄ arylalkynylaryl, Ci ₃ -C ₂₄ arylacylaryl, C ₇ -Ci ₈ arylacyl, C ₉ -Cj ₈ arylcarbocyclyl, C ₈ -Ci ₈ arylheterocyclyl, C ₉ -Ci ₈ arylheteroaryl, C ₈ -Ci ₈ alkenyloxyaryl, C ₈ -C] ₈ alkynyloxyaryl, Ci ₂ - C ₂₄ aryloxyaryl, C ₇ -Cj ₈ arylacyloxy, C ₉ -Ci ₈ arylcarbocyclyloxy, C ₈ -C ₁₈ arylheterocyclyloxy, C ₉ -C] ₈ arylheteroaryloxy, C ₇ -Ci ₈ alkylthioaryl, C ₈ -C ₁₈ alkenylthioaryl, C ₈ -CiS alkynylthioaryl, Cj ₂ -C ₂₄ arylthioaryl, C ₇ -Ci ₈ arylacylthio, C ₉ -C] ₈ arylcarbocyclylthio, C ₈ -Ci ₈ arylheterocyclylthio, and C ₉ -Ci ₈ arylheteroarylthio.

Still more specifically, Q may be a divalent form of a group selected from alkyl (e.g. Cj- C ₁₈ , Ci-C ₆ , Ci-C ₅ , C ₈ -C ₁₈ , or C ₉ -C ₈ ), aryl (e.g. C ₆ -C] ₈ ), heteroaryl (e.g. C ₃ -Ci ₈ ), carbocyclyl (e.g. C ₃ -Ci ₈ ), heterocyclyl (e.g. C ₂ -C ₁₈ ), alkylaryl (e.g. C ₇ -C ₂₄ ), alkylheteroaryl (e.g. C ₄ -Ci ₈ ), alkylcarbocyclyl (e.g. C ₄ -Ci ₈ ), and alkylheterocyclyl (e.g. C ₃ -Ci ₈ ).

In the lists above defining divalent groups from which Q may be selected, each alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, and heterocyclyl moiety may be optionally substituted. For avoidance of any doubt, where a given Q group contains two or more of such moieties (e.g. alkylaryl), each of such moieties may be optionally substituted with one, two, three or more optional substituents as herein defined.

In the lists above defining divalent groups from which Q may be selected, where a given Q group contains two or more subgroups (e.g. [group A] [group B]), the order of the subgroups are not intended to be limited to the order in which they are presented. Thus, a Q group with two subgroups defined as [group A] [group B] (e.g. alkylaryl) is intended to also be a reference to a Q with two subgroups defined as [group B][group A] (e.g. arylalkyl).

Where Q comprises an optionally substituted alkyl moiety, a preferred optional substituent includes where a -CH ₂ - group in the alkyl chain is replaced by a group selected from -O-, -S-, -NR ^a -, -C(O)- (i.e. carbonyl), -C(O)O- (i.e. ester), and -C(O)NR ³ - (i.e. amide), where R ^a is as defined below.

As a more specific example of such a vinyl substituted living polymerisation moiety, where the living polymerisation moiety is a RAFT moiety, general formula (I) or (Ia) may be represented as general formula (II), where Z and R are as hereinbefore defined in the context of formula (1) of Scheme 4:

Such vinyl substituted living polymerisation moieties may be homopolymerised or copolymerised with one or more other ethylenically unsaturated compounds. Those skilled in the art will appreciate that depending upon the conditions employed and the nature of the living polymerisation moiety, in addition to the vinyl group the living polymerisation moiety per se of general formula (I) may also participate in the polymerisation process. In that case, branched polymer structures may be formed. Through variation of parameters such as the type of living polymerisation moiety, the use and type of comonomer, and/or the reaction conditions employed, a person skilled in the art can therefore tailor the structure of polymer resulting from the polymerisation of these vinyl substituted living polymerisation moieties. Polymer formed by this approach can generally be prepared so as to provide for polymer having (1) a desirable concentration of covalently bound living polymerisation moieties, and (2) a molecular weight/viscosity suitable for electrospinning. Nevertheless, the resulting polymer may also be combined with one or more other polymers for electrospinning as outlined above.

Ethylenically unsaturated monomers that may be used in preparing the polymer having one or more living polymerisation moieties covalently bound thereto include those which can be polymerised by a free radical process. Such monomers should also be capable of being polymerised with other monomers. The factors which determine copolymerisability of various monomers are well documented in the art. For example, see: Greenlee, R.Z., in Polymer Handbook 3 ^rd Edition (Brandup, J., and Immergut. E.H. Eds) Wiley: New York, 1989 p 11/53. Suitable monomers include, but are not limited to, those of general formula

(III):

W U

M (πi) H V

where U and W are independently selected from -CO ₂ H, -CO ₂ R ² , -COR ² , -CSR ² ,

-CSOR ² , -COSR ² , -CONH ₂ , -CONHR ² , -CONR ² ₂ , hydrogen, halogen and optionally substituted Ci-C ₄ alkyl, or U and W form together a lactone, anhydride or imide ring that may itself be optionally substituted; where the optional substituents are independently selected from hydroxy, -CO ₂ H, -CO ₂ R ² , -COR ² , - CSR ² , -CSOR ² , -COSR ² , -CN, -CONH ₂ , -CONHR ² , -CONR ² ₂ , -OR ² , -SR ² , - O ₂ CR ² , -SCOR ² , and -OCSR ² ;

where V is selected from hydrogen, R ² , -CO ₂ H, -CO ₂ R ² , -COR ² , CN, -CSR ² , -

CSOR ² , -COSR ² , -CONH ₂ , -CONHR ² , -CONR ² ₂ , NHC(O)R ² , NR ² C(O)R ² , PO(OR ² ) ₃ , -OR ² , -SR ² , -O ₂ CR ² , -SCOR ² ,-OCSR ² and halogen;

where the or each R ² is independently selected from optionally substituted Cj-C ₂₂ alkyl, optionally substituted C ₂ -C ₂₂ alkenyl, C ₂ -C ₂₂ optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aralkyl, optionally substituted heteroarylalkyl, optionally substituted alkaryl, optionally substituted alkylheteroaryl and a polymer chain; preferred optional substituents for R ² include those selected from alkyleneoxidyl (epoxy), hydroxy, alkoxy, acyl, acyloxy, formyl, alkylcarbonyl, carboxy, sulfonic acid, alkoxy- or aryloxy- carbonyl, isocyanato, cyano, silyl, halo, amino, including salts and derivatives thereof. Preferred polymer chains include, but are not limited to, polyalkylene oxide (e.g. polyethylene oxide, polypropylene oxide and copolymers thereof), polyarylene ether and polyalkylene ether.

Examples of ethylenically unsaturated monomers include, but are not limited to, maleic anhydride, N-alkylmaleimide, N-arylmaleimide, dialkyl fumarate and cyclopolymerisable monomers, acrylate and methacrylate esters, acrylic and methacrylic acid, styrene and substituted styrene derivatives, acrylamide, methacrylamide, and methacrylonitrile, mixtures of these monomers, and mixtures of these monomers with other monomers.

Other examples of ethylenically unsaturated monomers include, but are not limited to, the following: methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethyIhexyl methacrylate, isobornyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, alpha-methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl acrylate, isobornyl acrylate, acrylic acid, benzyl acrylate, phenyl acrylate, acrylonitrile, styrene, functional methacrylates, acrylates and styrenes selected from glycidyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate (all isomers), hydroxybutyl methacrylate (all isomers), N,N-dimethylaminoethyl methacrylate, N ₅ N- diethylaminoethyl methacrylate, triethyleneglycol methacrylate, itaconic anhydride, itaconic acid, glycidyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate (all isomers), hydroxybutyl acrylate (all isomers), N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, triethyleneglycol acrylate, methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide, N-tert- butylmethacrylamide, N-n-butylmethacrylamide, N-isopropylacrylamide, N- methylolmethacrylamide, N-ethylolmethacrylamide, N-tert-butylacrylamide, N-n- butylacrylamide, N-methylolacrylamide, N-ethylolacrylamide, vinyl benzoic acid

(all isomers), diethylamino styrene (all isomers), alpha-methylvinyl benzoic acid (all isomers), diethylamino alpha-methylstyrene (all isomers), p-vinylbenzene sulfonic acid, p-vinylbenzene sulfonic sodium salt, trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, tributoxysilylpropyl methacrylate, dimethoxymethylsilylpropyl methacrylate, diethoxymethylsilylpropyl methacrylate, dibutoxymethylsilylpropyl methacrylate, diisopropoxymethylsilylpropyl methacrylate, dimethoxysilylpropyl methacrylate, diethoxysilylpropyl methacrylate, dibutoxysilylpropyl methacrylate, diisopropoxysilylpropyl methacrylate, trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, tributoxysilylpropylacrylate, dimethoxymethylsilylpropyl acrylate, diethoxymethylsilylpropyl acrylate, dibutoxymethylsilylpropyl acrylate, diisopropoxymethylsilylpropyl acrylate, dimethoxysilylpropyl acrylate, diethoxysilylpropyl acrylate, dibutoxysilylpropyl acrylate, diisopropoxysilylpropyl acrylate, vinyl acetate, vinyl butyrate, vinyl benzoate, vinyl chloride, vinyl fluoride, vinyl bromide, maleic anhydride, N-phenylmaleimide, N-butylmaleimide, N- vinylpyrrolidone, N-vinylcarbazoIe, butadiene, ethylene, and chloroprene. Where radical polymerisation techniques are employed to prepare the polymer having one or more living polymerisation moieties covalently bound thereto, the polymerisation will usually require initiation from a source of free radicals. The source of initiating radicals can be provided by any suitable method of generating free radicals, such as the thermally induced homolytic scission of suitable compound(s) (e.g. thermal initiators such as peroxides, peroxyesters, or azo compounds), the spontaneous generation from monomers (e.g. styrene), redox initiating systems, photochemically (e.g. UV radiation), or high energy radiation such as electron beam, X- or γ-radiation. The initiating system is chosen such that under the reaction conditions employed there is no substantial adverse interaction of the initiator or the initiating radicals with the selected living polymerisation moiety. The initiator will generally be selected to have the requisite solubility in the reaction medium.

Those skilled in the art will appreciate that in some cases the selected living polymerisation moiety may in itself be capable of providing the source of initiating radicals. For example, an iniferter moiety may be used to provide the source of initiating radicals.

Where a thermal initiator is used, it will generally be selected to have an appropriate half life at the temperature of polymerisation. Specific examples of thermal initiators include, but are not limited to, the following compounds:

2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-cyanobutane), dimethyl 2,2'- azobis(isobutyrate), 4,4'-azobis(4-cyanovaleric acid), 1,1'- azobis(cyclohexanecarbonitrile), 2-(t-butylazo)-2-cyanopropane, 2,2'-azobis{2- methyl-N-[l , 1 -bis(hydroxyrnethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis[2- methyl-N-(2-hydiOxyethyl)propionamide], 2,2'-azobis(N,N'- dimethyleneisobutyramidine) dihydrochloride, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutyramidine), 2,2'-azobis{2- methyI-N-[l , 1 -bis(hydroxymethyl)-2-hydroxyethyl]propionamide} , 2,2'-azobis{2- methyl-N- [1,1 -bis(hydroxymethyl)-2-ethyl]proρionamide} , 2,2'-azobis[2-methyl- N-(2-hydroxyethyl)propionamide], 2,2'-azobis(isobutyramide) dihydrate, 2,2'- azobis(2,2,4-trimethylpentane), 2,2'-azobis(2-methylpropane), t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyneodecanoate, t-butylperoxy isobutyrate, t-amyl peroxypivalate, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, dicumyl peroxide, dibenzoyl peroxide, dilauroyl peroxide, potassium peroxydisulfate, ammonium peroxydisulfate, di-t-butyl hyponitrite, dicumyl hyponitrite.

Where used, photochemical initiator systems will generally be selected to have the requisite solubility in the reaction medium and to also have an appropriate quantum yield for radical production under the conditions of polymerisation. Specific examples of such initiator systems include, but are not limited to, benzoin derivatives, benzophenone, acyl phosphine oxides, and photo-redox systems.

Where a redox initiator system is used, it will generally be selected to have the requisite solubility in the reaction medium and to also have an appropriate rate of radical production under the conditions of polymerisation. Specific examples of such initiating systems include, but are not limited to, combinations of the following oxidants and reductants:

oxidants: potassium, peroxydisulfate, hydrogen peroxide, t-butyl hydroperoxide,

reductants: iron (II), titanium (III), potassium thiosulfϊte, potassium bisulfite.

Other suitable initiating systems are described in well known texts. See, for example, Moad and Solomon "the Chemistry of Free Radical Polymerisation", Pergamon, London, 1995, pp 53-95.

The polymer having one or more living polymerisation moieties covalently bound thereto might also be formed by covalently attaching one or more living polymerisation moieties to a preformed polymer chain using well known coupling reactions. For example, preformed synthetically or biologically derived polymers may be modified by covalently attaching one or more living polymerisation moieties thereto using techniques well known in the art. Suitable synthetically or biologically derived polymers that may be employed include, but are not limited to, those outlined below.

Regardless of how the polymer having the covalently bound living polymerisation moieties is prepared, it will be appreciated that the polymer composition as a whole used in accordance with the method of the invention will have sufficient viscosity to allow electrospinning of fibres from the composition under the conditions employed. The polymer having the covalently bound living polymerisation moieties may provide the composition with sufficient viscosity in its own right, or it may be combined with one or more other polymers to achieve this.

There is no particular limitation on the type of such one or more other polymers that may be used, and they may include synthetically derived polymers formed by the radical polymerisation of one or more of the aforementioned ethylenically unsaturated monomers of general formula (III). Polymers formed by polymerisation techniques other than radical polymerisation, such as condensation polymerisation, may also be used. Such polymers may also include those that are biologically derived and those that are biodegradable, These various classes of polymer may of course also be used as a preformed polymer for covalently attaching one or more living polymerisation moieties as hereinbefore described.

Specific examples of such synthetically or biologically derived and biodegradable polymers that may be present in the polymer composition in addition to polymer having one or more living polymerisation moieties covalently bound thereto, and/or that may be used as a preformed polymer for covalently attaching one or more living polymerisation moieties as hereinbefore described, include, but are not limited to, polyolefins such as polyethylene, polypropylene, polyisobutylene, and ethylene-alpha-olefin copolymers; acrylic polymers and copolymers such as polyacrylates, polymethylmethacrylate, polyethylacrylate, and esters thereof; vinyl halide polymers and copolymers such as polyvinyl chloride; polyvinyl ethers such as polyvinyl methyl ether; polyvinylildene halides, such as polyvinylidene fluoride and polyvinylidene chloride; polyacrylonitrile; polyvinyl ketones; polyvinyl amines, polyvinyl aromatics such as polystyrene; polyvinyl esters, such as polyvinyl acetate; copolymers of vinyl monomers with each other and olefins, such as ethylene-methyl methacrylate copolymers, acrylonitrile-styrene copolymers, ABS resins, and ethylene-vinyl acetate copolymers; polyacylamides such as polymethacrylamide, poly(N-methylacrylamide), poly(N,N-dimethylacrylamide), poly(N- tert-butylmethacrylamide), poly(N-n-butylmethacrylamide), poly(N-isopropylacrylamide), poly(N-methylolmethacrylamide), poly(N-ethylolmethacrylamide), poly(N-tert- butylacrylamide), poly(N-n-butylacrylamide), poly(N-methylolacrylamide), and poly(N- ethylolacrylamide); natural and synthetic rubbers, including butadiene-styrene copolymers, polyisoprene, synthetic polyisoprene, polybutadiene, butadiene-acrylonitrile copolymers, polychloroprene rubbers, polyisobutylene rubbers, ethylene-propylene-diene rubbers, isobutylene-isoprene copolymers, and polyurethane rubbers; polyesters, such as polyethylene terephthalate, poly(α-hydroxyesters) and copolymers thereof such as polyglycolic acid, polylactic acid, poly(lactic-co-glycolic acid) (all stereo-isomeric forms thereof); polydioxanone; polyalkanoates such as poly(hydroxy butyrate), poly(hydroxy valerate) and co-polymers thereof such as poly(hydroxy butyrate valerate); polycarbonates; polyethers; polyetheretherketone; polyimides; polyacetals; poly(phenylene oxide)s; ionomers; polyamides; polysulphone; polyethersulfone; polyvinylpyrrolidone; fluoropolymers, cellulose and modified celluloses, cellulose starches and modified starches, dextrans, xanthan, bacterial exopolysaccharides, alginates, collagens, gelatine, silk fibroin, silks, keratins, elastic proteins, hyaluronic acid, fibronectin, fibrinogen, fibrin, oligopeptides, polypeptides, acellular matrix (decellularised tissue), polyphosphazenes, polyvinylalcohol, polyethylene glycol and thermosetting precursors (i.e. a crosslikable polymer) such as epoxies, phenolics, and vinyl ester resins optionally together with a suitable crosslinking agents and which precursors are crosslinked after the electrospun fibres are formed.

The polymer having one or more living polymerisation moieties covalently bound thereto can advantageously be prepared using techniques, reagents and equipment well known to those skilled in the art. The concentration of the living polymerisation moieties in the polymer composition can influence the density of living polymerisation moieties that are present on the surface of the resulting electrospun fibre. Generally, the molar ratio of the living polymerisation moieties to the polymerised monomer residues that form the total polymer content of the polymer composition is at least 0.1%, or at least 1%.

In addition to polymer, the polymer composition may comprise one or more other components to facilitate electrospinning and/or to modify the properties of the resulting electrospun polymer fibre. For example, the polymer composition may comprise one or more solvents to solubilise the polymer components and form the liquid polymer composition. Those skilled in the art will be able to select the appropriate solvent or solvent system to the polymers used. The polymer composition may also comprise one or more salts such as an organic salt (e.g. an alkyl quaternary ammonium compound) to adjust the charge density of the composition and produce more uniform dimeter fibres during the electrospinning process.

Conventional electrospinning equipment, techniques and reagents can advantageously be used in accordance with the method of the invention.

Apart form varying the molar ratio of the living polymerisation moieties to the polymerised monomer residues that form the total polymer content of the polymer composition, the density of living polymerisation moieties presented on the surface of the resulting electrospun fibre may be tailored by manipulating one or more of the electrospinning process conditions.

For example, the voltage applied during electrospinning may be adjusted. In particular, it has been found that increasing the voltage can increase the density of living polymerisation moieties presented on the surface of the resulting electrospun fibre. This can be achieved by using polarisable living polymerisation moieties or polarisable polymers with the living polymerisation moiety attached, which can be driven to the surface of the fibre under the influence of the electrical field during electrospinning. The voltage employed during electrosp inning will generally range from about +1OkV to about +4OkV.

A further approach for tailoring the density of living polymerisation moieties presented on the surface of the electrospun fibre might involve covalently attaching to or near the living polymerisation moieties one or more atoms or groups that facilitate migration of the living polymerisation moieties to the surface of the fibre as it is produced. For example, fluorine atoms or groups containing fluorine atoms may be covalently attached to or near the living polymerisation moieties. Other such surface seeking groups might include poly(ethylene glycol) (PEG) or silicon containing groups such as siloxanes or poly(dimethyl siloxanes)

(PDMS).

Conventional analytical techniques may be used to evaluate the density of the living polymerisation moieties presented on the surface of the electrospun fibre. Those skilled in the art will be able to select an appropriate technique depending upon the nature of the living polymerisation moiety to be assessed. For example, X-ray photoelectron spectroscopy (XPS) may be used for such an evaluation.

Generally, the electrospun polymer fibres for use in the manufacture of polymer brushes according to the invention will have living polymerisation moieties presented on the surface thereof in an amount ranging from about 0.01 to about 10 moieties per nm , as measured by XPS.

Upon forming the electrospun fibre having living polymerisation moieties located on its surface, the fibre can advantageously be used without modification in the subsequent graft polymerisation step according to the method.

The living polymerisation technique employed to form the graft polymer chains on the surface of the fibre will of course vary depending upon the nature of the living polymerisation moiety presented on the surface of the electrospun fibre. Those skilled in the art will be able to select appropriate conditions, reagents and equipment to perform such polymerisation.

As part of this living polymerisation grafting process, one or more ethylenically unsaturated monomers are polymerised "under the control" of the living polymerisation moieties on the surface of the electrospun fibre. By the monomers being polymerised

"under the control" of the living polymerisation moieties is meant that polymerisation of the monomers proceeds with living polymerisation characteristics that are mediated or controlled by the living polymerisation moiety. By being controlled in this manner, it will be appreciated that the resulting polymer chain will be a living polymer chain as hereinbefore defined.

Ethylenically unsaturated monomers and means for generating a source of radicals as hereinbefore described may be used in forming the grafted polymer chains.

Employing living polymerisation to form the polymer chains grafted to the surface of the fibre advantageously enables their composition and architecture to be controlled. For example, the grafted living polymer chains may be prepared so as to have a linear, branched, star, block copolymer, random copolymer, homopolymer, and/or tapered/gradient copolymer structure.

The grafted living polymer chains may be prepared so as to have a desired molecular weight. Generally, the grafted living polymer chains will have a number average molecular weight ranging from about 1 kDa to about 500 IcDa ₅ for example from about 1 IcDa to about 300 IcDa, or from about 1 IcDa to about 100 IcDa. The molecular weight of the grafted chains is that as would be determined by cleaving the chains from the electrospun fibre and measuring the molecular weight of the cleaved chians by GPC.

By virtue of the living polymerisation moieties presented on the surface of the electrospun fibre being covalently bound to polymer that forms at least part of the fibre, it will be appreciated that the grafted polymer chains are securely anchored to the fibre and are therefore not prone to thermal or solvent desorption. The grafted polymer chains therefore can provide for a relatively stable brush layer.

Through control of the density of living polymerisation moieties presented on the surface of the electrospun polymer fibre and the composition and architecture of the living polymer chains grafted thereto, the method of the invention provides an efficient and effective means of preparing polymer brushes with a high degree of control.

The density of the grafted living polymer chains on the surface of the electrospun polymer fibre will at least in part be determined by the concentration of living polymerisation moieties presented on the surface of the fibre. Generally, the polymer brushes in accordance with the invention will be prepared so as to have about 0.01 to about 2 grafted polymer chains nm ^'2 , or about 0.1 to about 1 grafted polymer chains urn ^'2 , as determined by graft height measurement using ellipsometry, and determination of the bulk density and molecular weight of the graft.

An advantageous feature of such control is that the grafted living polymer chains may be prepared such that they inherently have the desired properties for a given application, or they can be prepared so as to enable them to be suitably modified to attain the desired properties for a given application.

In one embodiment, the grafted living polymer chains comprise a moiety that reduces the ability of biomolecules, such as proteins, to adsorb on the polymer brush, relative to the electrospun polymer fibre absent the grafted living polymer chains. In other words, the moiety imparts to the polymer brush an ability to resist biomolecule adsorption. The living polymer chains may be provided with such a moiety by any suitable means. For example, one or more of the ethylenically unsaturated monomers polymerised to form the living polymer chains may comprise a moiety that reduces the ability of biomolecules to adsorb on the polymer brush, relative to the electrospun polymer fibre without the living polymer chains. Alternatively, the method of the invention may further comprise covalently attaching to the so formed living polymerisation chains moieties that reduce the ability of biomolecules to adsorb on the resulting modified polymer brush, relative to the polymer brush absent the covalently attached moieties.

Moieties that can impart to the polymer brush an ability to resist biomolecule adsorption include, but are not limited to, poly(acrylamide), poly(methacrylamide), poly(N- methylacrylamide), poly(N,N-dimethyl(meth)acrylamide), poly(jV- isopropyl(meth)acrylamide), poly(N-(2-hydroxypropyl)methacrylamide), poly(iV- methylolacrylamide), poly(7V-vinylformamide), ρoly(7V-vinylacetamide), poly(N-vinyl-N- methylacetamide), poly(poly(ethylene glycol)(meth)acrylate), poly(poly(ethylene glycol) monomethyl ether mono(meth)acrylate), poly(7V-vinyl-2-pyrrolidone), poly(glycerolmono(meth)acrylate), poly(2-hydroxyethyl(meth)acrylate), polyvinyl methyl sulphone), poly(vinyl acetate), polymers formed from ethylenically unsaturated mono-, di-, tri and poly(saccharide)(s) where the saccharide moiety is nett neutral, polymers formed from zwitterionic monomers such as 3-((2-(meth)acryloyloxy)ethyl)dimethylammonio) propane- 1 -sulfonate, and 2-((meth)acryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate, and copolymers thereof.

As used herein the term "biomolecule" is intended to mean molecules that are produced by an organism, tissue or cell. Biomolecules include, but are not limited to peptides, oligopeptides, polypeptides, proteins, nucleic acids, nucleotides, carbohydrates and lipids.

In connection with modifying the grafted living polymer chains to attain the desired properties for a given application, by virtue of the living polymerisation technique used to prepare them they will generally retain a living polymerisation moiety as an end group. In some cases, it may be desirable to perform further chemistry using these living polymerisation moiety end groups. For example, where the living polymer chains retain a RAFT moiety, the moiety may be reacted with a radical species such as tris(trimethylsilyl)silyl radical to promote homiletic cleavage of a CS bond producing a hydro -terminated polymer chain. The RAFT moiety can also be hydrolysed under a variety of simple conditions to generate a terminal thiol group. For example, aminolysis of a trithiocarbonate using simple amines like butyl amine, dibutyl amine or ethanolamine will generate a thiol. The RAFT moiety may of course also be used to control further polymerisation of one or more ethylenically unsaturated monomers.

Similarly, halide end groups of living polymer chains that arise from the use of ATRP moieties may be displaced with azide to create and azide terminated polymer chain. This then allows the use of copper (I) catalysed 1,3-cycloaddition reactions with terminal alkynes in what is commonly known as a click reaction to produce a 1,2,3-triazole group. The use of functional alkynes would therefore result in that functionality being located at the end of the polymer chain (see Evans R.A. Aust J Chem 2007, 60, 384-395 for a review of the use of click chemistry in polymer and surface sciences).

Apart from chemistry made available from the living polymerisation moieties per se, chemical modification of the moieties can therefore open up a diverse array of alternative means for creating unique surfaces. For example, such modified moieties may enable the brush layer to be functionalised with bioactive moieties. In particular, living polymer chains that retain a RAFT moiety may be reacted to provide for a thiol group which in turn can be activated to promote disulfide formation with other thiols. As many proteins and peptides contain thiols there is the potential to functionalise the surface with such bioactive moieties.

Modification of the brush layer, for example with bioactive moieties, may also be achieved by covalently attaching a bioactive moiety to ethylenically unsaturated monomer that is polymerised under the control of the living polymerisation moieties and forms the living polymer chains grafted to the surface of the fibre. Alternatively, bioactive moieties or other moieties can be covalently attached to the brush layer using functional groups on the brush other than the living polymerisation moieties.

As used herein the term "bioactive moiety" is intended to mean bioactive, diagnostic, and prophylactic molecules. Bioactive moieties include, but are not limited to, synthetic, recombinant or isolated peptides and proteins such as antibodies and antigens, synthetic small molecule peptidomimetics, mimetics of cell adhesion motifs, other classes of drugs, small molecule growth factor mimetics, receptor ligands, enzymes, and adhesion peptides; nucleotides and polynucleic acids such as DNA and antisense nucleic acid molecule; activated sugars and polysaccharides; bacteria; viruses; and organic drug molecules such as antibiotics, antiinflammatories, and antifungal agents.

As used herein, the term "protein" is intended to refer to compounds composed, at least in part, of amino acid residues linked by amide bonds (i.e., peptide bonds). The term "protein" is intended to include peptides, and polypeptides. The term "protein" is further intended to include peptide analogues, peptide derivatives and peptidomimetics that mimic the chemical structure of a protein composed of naturally occurring amino acids. Examples of peptide analogues include peptides comprising one or more non-natural amino acids. Examples of peptide derivatives include peptides in which an amino acid side chain, the peptide backbone, or the amino- or carboxy-terminus has been derived (e.g., peptidic compounds with methylated amide linkages). The terms "protein", "peptide" and "polypeptide" refer to both naturally occurring chemical entities and structurally similar bioactive equivalents derived from either endogenous, exogenous, or synthetic sources and is used to mean polymers of amino acids linked together by an amide type linkage known as a peptide bond.

Under certain circumstances, it may be desirable to incorporate "free" or non-grafted polymer into the brush layer to form a blend of the grafted living polymer chains and the non-grafted polymer. The non-grafted polymer may be formed in situ during the polymerisation of monomer that gives rise to the grafted living polymer chains, or introduced to the brush layer after it is formed.

It may also be desirable to modify the brush layer by crosslinking the grafted living polymer chains thereby altering the physical properties, such as the elasticity, of the brush layer. The grafted living polymer chains may be crosslinked as they are being formed or as a separate process after they are formed.

By "crosslinking" the grafted living polymer chains or brush layer is meant a reaction involving sites or groups on polymer chains or an interaction between polymer chains (as they are being formed or after being formed) that results in at least two of the grafted polymer chains being covalently tethered together. By the grafted living polymer chains or brush layer being "crosslinked" is meant that the polymer chains have undergone such a crosslinldng reaction.

Those skilled in the art will appreciate that the crosslinking of polymer chains may be achieved in numerous ways. For example, crosslinldng may be achieved using multi- ethylenically unsaturated monomers. In that case, crosslinldng is typically derived through a free radical reaction mechanism.

Alternatively, crosslinking may be achieved using ethylenically unsaturated monomers which also contain a reactive functional group that is not susceptible to taking part in free radical reactions (i.e. "functionalised" unsaturated monomers). In that case, such monomers may be incorporated into the polymer backbone of the polymer chains through polymerisation of the unsaturated group, and the resulting pendant functional group provides means through which crosslinking may occur. By utilising monomers that provide complementary pairs of reactive functional groups (i.e. groups that will react with each other), the pairs of reactive functional groups can react through non-radical reaction mechanisms to provide crosslinks.

A variation on using complementary pairs of reactive functional groups is where the monomers are provided with non-complementary reactive functional groups. In that case, the functional groups will not react with each other but instead provide sites which can subsequently be reacted with a crosslinldng agent to form the crosslinks. It will be appreciated that such crosslinldng agents will be used in an amount to react with substantially all of the non-complementary reactive functional groups. Formation of the crosslinks under these circumstances will generally occur after polymerisation of the monomers.

A combination of these crosslinking techniques may be used.

The terms "multi-ethylenically unsaturated monomers" and "functionalised unsaturated monomers" mentioned above can conveniently and collectively also be referred to herein as "crosslinking ethylenically unsaturated monomers" or "crosslinking monomers". By the general term "crosslinking ethylenically unsaturated monomers" or "crosslinking monomers" it is meant an ethylenically unsaturated monomer through which a crosslink is or will be derived.

It will be appreciated that not all unsaturated monomers that contain a functional group can be used for the purpose of functioning as a crosslinking monomer. For example, acrylic acid should not be considered as a crosslinking monomer unless it is used to provide a site through which a crosslink is to be derived.

Examples of suitable multi-ethylenically unsaturated monomers that may be used to promote crosslinking include ethylene glycol di(meth)acrylate, Methylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1 ,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol di(meth)acrylate, glycerol allyloxy di(meth)acrylate, 1,1,1- tris(hydroxymethyl)ethane di(meth)acrylate, 1,1,1 -tris(hydroxymethyl)ethane tri(meth)acrylate, 1 , 1 , 1 -tris(hydroxymethyl)propane di(meth)acrylate, 1,1,1- tris(hydroxymethyl)propane tri(meth)acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl phthalate, diallyl terephthalte, divinyl benzene, methylol (meth)acrylamide, triallylamine, oleyl maleate, glyceryl propoxy triacrylate, allyl methacrylate, methacrylic anhydride and methylenebis (meth) acrylamide.

Examples of suitable ethylenically unsaturated monomers which contain a reactive functional group that is not susceptible to taking part in free radical reactions include acetoacetoxyethyl methacrylate, glycidyl methacrylate, iV-methylolacrylamide, (isobutoxymethyl)acrylamide, hydroxyethyl acrylate, Λ-butyl-carbodiimidoethyl methacrylate, acrylic acid, γ-methacryloxypropyltriisopiOpoxysilane, 2-isocyanoethyl methacrylate and diacetone acrylamide.

Examples of suitable pairs of monomers mentioned directly above that provide complementary reactive functional groups include N-methylolacrylamide and itself, (isobutoxymethyl)acrylamide and itself, γ-methacryloxypropyltriisopropoxysilane and itself, 2-isocyanoethyl methacrylate and hydroxyethyl acrylate, and /-butyl- carbodiimidoethyl methacrylate and acrylic acid.

Examples of suitable crosslinking agents that can react with the reactive functional groups of one or more of the functionalised unsaturated monomers mentioned above include hexamethylene diamine, melamine, trimethylolpropane tris(2-methyl-l-aziridine propionate) and adipic bishydrazide. Examples of pairs of crosslinking agents and functionalised unsaturated monomers that provide complementary reactive groups include hexamethylene diamine and acetoacetoxy ethyl methacrylate, hexamethylene diamine and glycidyl methacrylate, melamine and hydroxyethyl acrylate, trimethylolpropane tris(2- methyl-1-aziridine propionate) and acrylic acid, adipic bishydrazide and diacetone acrylamide.

The brush layer may also be used as a platform to covalently attach polymers synthesised by non-living polymerisation.

As used herein, the term "alkyl", used either alone or in compound words denotes straight chain, branched or cyclic alkyl, preferably C _J-20 alkyl, e.g. Ci _-I0 or Ci _-6 . Examples of straight chain and branched alkyl include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec- butyl, t-butyl, «-pentyl, 1,2-dimethylpropyl, 1,1-dimethyl-propyl, hexyl, 4-methylpentyl, 1- methylpentyl, 2-methylpentyl, 3-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3- dimethylbutyl, 1,2-dimethylbutyl, 1,3 -dimethyl butyl, 1 ,2,2-trimethylpropyl, 1,1,2- trimethylpropyl, heptyl, 5-methylhexyl, 1-methylhexyl, 2,2-dimethylpentyl, 3,3- dimethylpentyl, 4,4-dimethylpentyl, 1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4- dimethyl-pentyl, 1,2,3-trimethylbutyl, 1,1,2-trimethylbutyl, 1,1,3-trimethylbutyl, octyl, 6- methylheptyl, 1-methylheptyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-, 2-, 3-, A-, S-, 6- or 7- methyloctyl, 1-, 2-, 3-, 4- or 5-ethylheptyl, 1-, 2- or 3-propylhexyl, decyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- and 8-methylnonyl, 1-, 2-, 3-, A-, 5- or 6-ethyloctyl, 1-, 2-, 3- or 4-propylheptyl, undecyl, 1-, 2-, 3-, A-, 5-, 6-, 7-, 8- or 9-methyldecyl, 1-, 2-, 3-, A-, 5-, 6- or 7-ethylnonyl, 1-, 2-, 3-, 4- or 5-propyloctyl, 1-, 2- or 3-butylheptyl, 1-pentylhexyl, dodecyl, 1-, 2-, 3-, A-, 5-, 6-, 7-, 8-, 9- or 10-methylundecyl, 1-, 2-, 3-, A-, 5-, 6- ₅ 7- or 8-ethyldecyl, 1-, 2-, 3-, A-, 5- or 6-propylnonyl, 1-, 2-, 3- or 4-butyloctyl, 1-2-pentylheptyl and the like. Examples of cyclic alkyl include mono- or polycyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl and the like. Where an alkyl group is referred to generally as "propyl", butyl" etc, it will be understood that this can refer to any of straight, branched and cyclic isomers where appropriate. An alkyl group may be optionally substituted by one or more optional substituents as herein defined.

The term "alkenyl" as used herein denotes groups formed from straight chain, branched or cyclic hydrocarbon residues containing at least one carbon to carbon double bond including ethylenically mono-, di- or polyunsaturated alkyl or cycloalkyl groups as previously defined, preferably C _2-20 alkenyl (e.g. C _2-10 or C _2-6 ). Examples of alkenyl include vinyl, allyl, 1 -methyl vinyl, butenyl, iso-butenyl, 3-methyl-2-butenyl, 1-pentenyl, cyclopentenyl, 1 -methyl-cyclopentenyl, 1-hexenyl, 3-hexenyl, cyclohexenyl, 1-heptenyl, 3-heptenyl, 1-octenyl, cyclooctenyl, 1-nonenyl, 2-nonenyl, 3-nonenyl, 1-decenyl, 3- decenyl, 1,3-butadienyl, 1,4-pentadienyl, 1,3-cyclopentadienyl, 1,3-hexadienyl, 1,4- hexadienyl, 1,3-cyclohexadienyl, 1,4-cyclohexadienyl, 1,3-cycloheptadienyl, 1,3,5- cycloheptatrienyl and 1,3,5,7-cyclooctatetraenyl. An alkenyl group may be optionally substituted by one or more optional substituents as herein defined.

As used herein the term "alkynyl" denotes groups formed from straight chain, branched or cyclic hydrocarbon residues containing at least one carbon-carbon triple bond including ethylenically mono-, di- or polyunsaturated alkyl or cycloalkyl groups as previously defined. Unless the number of carbon atoms is specified the term preferably refers to C ₂ - ₂₀ alkynyl (e.g. C ₂ - ₁₀ or C _2-6 ). Examples include ethynyl, 1-propynyl, 2-propynyl, and butynyl isomers, and pentynyl isomers. An alkynyl group may be optionally substituted by one or more optional substituents as herein defined.

The term "halogen" ("halo") denotes fluorine, chlorine, bromine or iodine (fluoro, chloro, bromo or iodo). The term "aryl" (or "carboaryl") denotes any of single, polynuclear, conjugated and fused residues of aromatic hydrocarbon ring systems. Examples of aryl include phenyl, biphenyl, terphenyl, quaterphenyl, naphthyl, tetrahydronaphthyl, anthracenyl, dihydroanthracenyl, benzanthracenyl, dibenzanthracenyl, phenantlxrenyl, fluorenyl, pyrenyl, idenyl, azulenyl, chrysenyl. Preferred aryl include phenyl and naphthyl. An aryl group may or may not be optionally substituted by one or more optional substituents as herein defined. The term "arylene" is intended to denote the divalent form of aryl.

The term "carbocyclyl" includes any of non-aromatic monocyclic, poly cyclic, fused or conjugated hydrocarbon residues, preferably C _3-20 (e.g. C _3- J ₀ or C _3-8 ). The rings may be saturated, e.g. cycloalkyl, or may possess one or more double bonds (cycloalkenyl) and/or one or more triple bonds (cycloalkynyl). Particularly preferred carbocyclyl moieties are 5- 6-membered or 9-10 membered ring systems. Suitable examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclopentenyl, cyclohexenyl, cyclooctenyl, cyclopentadienyl, cyclohexadienyl, cyclooctatetraenyl, indanyl, decalinyl and indenyl. A carbocyclyl group may be optionally substituted by one or more optional substituents as herein defined. The term " carbocyclyl ene" is intended to denote the divalent form of carbocyclyl.

The term "heteroatom" or "hetero" as used herein in its broadest sense refers to any atom other than a carbon atom which may be a member of a cyclic organic group. Particular examples of heteroatoms include nitrogen, oxygen, sulfur, phosphorous, boron, silicon, selenium and tellurium, more particularly nitrogen, oxygen and sulfur.

The term "heterocyclyl" when used alone or in compound words includes any of monocyclic, polycyclic, fused or conjugated hydrocarbon residues, preferably C _3-20 (e.g. C _3-I0 or C _3-8 ) wherein one or more carbon atoms are replaced by a heteroatom so as to provide a non-aromatic residue. Suitable heteroatoms include O, N, S, P and Se, particularly O, N and S. Where two or more carbon atoms are replaced, this may be by two or more of the same heteroatom or by different heteroatoms. The heterocyclyl group may be saturated or partially unsaturated, i.e. possess one or more double bonds. Paxticularly preferred heterocyclyl are 5-6 and 9-10 membered heterocyclyl. Suitable examples of heterocyclyl groups may include azridinyl, oxiranyl, thiiranyl, azetidinyl, oxetanyl, thietanyl, 2H-pyrrolyl, pyrrolidinyl, pyrrolinyl, piperidyl, piperazinyl, morpholinyl, indolinyl, imidazolidinyl, imidazolinyl, pyrazolidinyl, thiomorpholinyl, dioxanyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydropyrrolyl, tetrahydrothiophenyl, pyrazolinyl, dioxalanyl, thiazolidinyl, isoxazolidinyl, dihydropyranyl, oxazinyl, thiazinyl, thiomorpholinyl, oxathianyl, dithianyl, trioxanyl, thiadiazinyl, dithiazinyl, trithianyl, azepinyl, oxepinyl, thiepinyl, indenyl, indanyl, 3H-indolyl, isoindolinyl, 4H-quinolazinyl, chromenyl, chromanyl, isochromanyl, pyranyl and dihydropyranyl. A heterocyclyl group may be optionally substituted by one or more optional substituents as herein defined. The term "heterocyclylene" is intended to denote the divalent form of heterocyclyl.

The term "heteroaryl" includes any of monocyclic, polycyclic, fused or conjugated hydrocarbon residues, wherein one or more carbon atoms are replaced by a heteroatom so as to provide an aromatic residue. Preferred heteroaryl have 3-20 ring atoms, e.g. 3-10. Particularly preferred heteroaryl are 5-6 and 9-10 membered bicyclic ring systems. Suitable heteroatoms include, O, N ₅ S, P and Se, particularly O, N and S. Where two or more carbon atoms are replaced, this may be by two or more of the same heteroatom or by different heteroatoms. Suitable examples of heteroaryl groups may include pyridyl, pyrrolyl, thienyl, imidazolyl, furanyl, benzothienyl, isobenzothienyl, benzofuranyl, isobenzofuranyl, indolyl, isoindolyl, pyrazolyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolizinyl, quinolyl, isoquinolyl, phthalazinyl, 1,5-naphthyridinyl, quinozalinyl, quinazolinyl, quinolinyl, oxazolyl, thiazolyl, isothiazolyl, isoxazolyl, triazolyl, oxadialzolyl, oxatriazolyl, triazinyl, and furazanyl. A heteroaryl group may be optionally substituted by one or more optional substituents as herein defined. The term "heteroarylene" is intended to denote the divalent form of heteroaryl.

The term "acyl" either alone or in compound words denotes a group containing the moiety

C=O (and not being a carboxylic acid, ester or amide) Preferred acyl includes C(O)-R ⁶ , wherein R ^e is hydrogen or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, carbocyclyl, or heterocyclyl residue. Examples of acyl include formyl, straight chain or branched alkanoyl (e.g. Ci _-20 ) such as acetyl, propanoyl, butanoyl, 2-methylpropanoyl, pentanoyl, 2,2- dimethylpropanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, decanoyl, undecanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, pentadecanoyl, hexadecanoyl, heptadecanoyl, octadecanoyl, nonadecanoyl and icosanoyl; cycloalkylcarbonyl such as cyclopropylcarbonyl cyclobutylcarbonyl, cyclopentylcarbonyl and cyclohexylcarbonyl; aroyl such as benzoyl, toluoyl and naphthoyl; aralkanoyl such as phenylalkanoyl (e.g. phenylacetyl, phenylpropanoyl, phenylbutanoyl, phenylisobutylyl, phenylpentanoyl and phenylhexanoyl) and naphthylalkanoyl (e.g. naphthylacetyl, naphthylpropanoyl and naphthylbutanoyl]; aralkenoyl such as phenylalkenoyl (e.g. phenylpropenoyl, phenylbutenoyl, phenylmethacryloyl, phenylpentenoyl and phenylhexenoyl and naphthylalkenoyl (e.g. naphthylpropenoyl, naphthylbutenoyl and naphthylpentenoyl); aryloxyalkanoyl such as phenoxyacetyl and phenoxypropionyl; arylthiocarbamoyl such as phenylthiocarbamoyl; arylglyoxyloyl such as phenylglyoxyloyl and naphthylglyoxyloyl; arylsulfonyl such as phenylsulfonyl and napthylsulfonyl; heterocycliccarbonyl; heterocyclicalkanoyl such as thienylacetyl, thienylpropanoyl, thienylbutanoyl, thienylpentanoyl, thienylhexanoyl, thiazolylacetyl, thiadiazolylacetyl and tetrazolylacetyl; heterocyclicalkenoyl such as heterocyclicpropenoyl, heterocyclicbutenoyl, heterocyclicpentenoyl and heterocyclichexenoyl; and heterocyclicglyoxyloyl such as thiazolyglyoxyloyl and thienylglyoxyloyl. The R ^e residue may be optionally substituted as described herein.

The term "sulfoxide", either alone or in a compound word, refers to a group -S(O)R ^f wherein R is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl, and aralkyl. Examples of prefeiτed R include C _1-2O aIlCyI, phenyl and benzyl.

The term "sulfonyl", either alone or in a compound word, refers to a group S(O) ₂ -R ^f , wherein R ^r is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl and aralkyl. Examples of preferred R ^f include phenyl and benzyl. The term "sulfonamide", either alone or in a compound word, refers to a group S(O)NR ^f R ^f wherein each R ^f is independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl, and aralkyl. Examples of preferred R ^f include Cj- ₂ oalkyl, phenyl and benzyl, In a preferred embodiment at least one R ^f is hydrogen. In another form, both R ^f are hydrogen.

The term, "amino" is used here in its broadest sense as understood in the art and includes groups of the formula NR ^a R ^b wherein R ^a and R ^b may be any independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, heterocyclyl, arylalkyl, and acyl. R ^a and R ^b , together with the nitrogen to which they are attached, may also form a monocyclic, or polycyclic ring system e.g. a 3-10 membered ring, particularly, 5-6 and 9- 10 membered systems. Examples of "amino" include NH ₂ , NHalkyl (e.g. Ci.2 _O alkyl), NHaryl (e.g. NHphenyl), NHaralkyl (e.g. NHbenzyl), NHacyl (e.g. NHC(O)C i _-20 alkyl, NHC(O)phenyl), Nalkylalkyl (wherein each alkyl, for example Ci _-20 , may be the same or different) and 5 or 6 membered rings, optionally containing one or more same or different heteroatoms (e.g. O, N and S).

The term "amido" is used here in its broadest sense as understood in the art and includes groups having the formula C(O)NR ^a R ^b , wherein R ^a and R ^b are as defined as above. Examples of amido include C(O)NH ₂ , C(O)NHalkyl (e.g. C _1-2O alkyl), C(O)NHaryl (e.g. C(O)NHphenyl), C(O)NHaralkyl (e.g. C(O)NHbenzyl), C(O)NHacyl (e.g. C(O)NHC(O)Ci _-20 alkyl, C(0)NHC(O)phenyl), C(O)Nalkylalkyl (wherein each alkyl, for example Ci _-2O , may be the same or different) and 5 or 6 membered rings, optionally containing one or more same or different heteroatoms (e.g. O, N and S).

The term "carboxy ester" is used here in its broadest sense as understood in the art and includes groups having the formula CO ₂ R ^g , wherein R ^g may be selected from groups including alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, heterocyclyl, aralkyl, and acyl. Examples of carboxy ester include C0 ₂ Ci _-2 oalkyl, CO ₂ aryl (e.g.. CO ₂ phenyl), CO ₂ aralkyl (e.g. CO ₂ benzyl). As used herein, the term "aryloxy" refers to an "aryl" group attached through an oxygen bridge. Examples of aryloxy substituents include phenoxy, biphenyloxy, naphthyloxy and the like.

As used herein, the term "acyloxy" refers to an "acyl" group wherein the "acyl" group is in turn attached through an oxygen atom. Examples of "acyloxy" include hexylcarbonyloxy (heptanoyloxy), cyclopentylcarbonyloxy, benzoyloxy, 4-chlorobenzoyloxy, decylcarbonyloxy (undecanoyloxy), propylcarbonyloxy (butanoyloxy), octylcarbonyloxy (nonanoyloxy), biphenylcarbonyloxy (eg 4-phenylbenzoyloxy), naphthylcarbonyloxy (eg 1 -naphthoyloxy) and the like.

As used herein, the term "alkyloxycarbonyl" refers to a "alkyloxy" group attached through a carbonyl group. Examples of "alkyloxycarbonyl" groups include butylformate, sec- butylformate, hexylformate, octylformate, decylformate, cyclopentylformate and the like.

As used herein, the term "arylalkyl" refers to groups formed from straight or branched chain alkanes substituted with an aromatic ring. Examples of arylalkyl include phenylmethyl (benzyl), phenylethyl and phenylpropyl.

As used herein, the term "alkylaryl" refers to groups formed from aryl groups substituted with a straight chain or branched alkane. Examples of alkylaryl include methylphenyl and isopropylphenyl.

In this specification "optionally substituted" is taken to mean that a group may or may not be substituted or fused (so as to form a condensed polycyclic group) with one, two, three or more of organic and inorganic groups, including those selected from: alkyl, alkenyl, alkynyl, carbocyclyl, aryl, heterocyclyl, heteroaryl, acyl, aralkyl, alkaryl, alkheterocyclyl, alkheteroaryl, alkcarbocyclyl, halo, haloalkyl, haloalkenyl, haloalkynyl, haloaryl, halocarbocyclyl, haloheterocyclyl, haloheteroaryl, haloacyl, haloaryalkyl, hydroxy, hydroxy alkyl, hydroxyalkenyl, hydroxy alkynyl, hydroxycarbocyclyl, hydroxyaryl, hydroxyheterocyclyl, hydroxyheteroaryl, hydroxyacyl, hydroxyaralkyl, alkoxyalkyl, alkoxyalkenyl, alkoxyalkynyl, alkoxycarbocyclyl, alkoxyaryl, alkoxyheterocyclyl, alkoxyheteroaryl, alkoxyacyl, alkoxyaralkyl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, carbocyclyloxy, aralkyloxy, heteroaryloxy, heterocyclyloxy, acyloxy, haloalkoxy, haloalkenyloxy, haloalkynyloxy, haloaryloxy, halocarbocyclyloxy, haloaralkyloxy, haloheteroaryloxy, haloheterocyclyloxy, haloacyloxy, nitro, nitroalkyl, nitroalkenyl, nitroalkynyl, nitroaryl, nitroheterocyclyl, nitroheteroayl, nitrocarbocyclyl, nitroacyl, nitroaralkyl, amino (NH ₂ ), alkylamino, dialkylamino, alkenylamino, alkynylamino, arylamino, diarylamino, aralkylamino, diaralkyl amino, acylamino, diacylamino, heterocyclamino, heteroarylamino, carboxy, carboxyester, amido, alkylsulphonyloxy, arylsulphenyloxy, alkylsulphenyl, arylsulphenyl, thio, alkylthio, alkenylthio, alkynylthio, arylthio, aralkylthio, carbocyclylthio, heterocyclylthio, heteroarylthio, acylthio, sulfoxide, sulfonyl, sulfonamide, aminoalkyl, aminoalkenyl, aminoalkynyl, aminocarbocyclyl, aminoaryl, aminoheterocyclyl, aminoheteroaryl, aminoacyl, aminoaralkyl, thioalkyl, thioalkenyl, thioalkynyl, thiocarbocyclyl, thioaryl, thioheterocyclyl, thioheteroaryl, thioacyl, thioaralkyl, carboxyalkyl, carboxyalkenyl, carboxyalkynyl, carboxy carbocyclyl, carboxyaryl, carboxyheterocyclyl, carboxyheteroaryl, carboxyacyl, carboxyaralkyl, carboxyesteralkyl, carboxyesteralkenyl, carboxyesteralkynyl, carboxyestercarbocyclyl, carboxyesteraryl, carboxyesterheterocyclyl, carboxyesterheteroaryl, carboxyesteracyl, carboxyesteraralkyl, amidoalkyl, amidoalkenyl, amidoalkynyl, amidocarbocyclyl, amidoaryl, amidoheterocyclyl, amidoheteroaryl, amidoacyl, amidoaralkyl, formylalkyl, formylalkenyl, formylalkynyl, formylcarbocyclyl, formylaryl, formylheterocyclyl, formylheteroaryl, formylacyl, formylaralkyl, acylalkyl, acylalkenyl, acylalkynyl, acylcarbocyclyl, acylaryl, acylheterocyclyl, acylheteroaryl, acylacyl, acylaralkyl, sulfoxidealkyl, sulfoxidealkenyl, sulfoxidealkynyl, sulfoxidecarbocyclyl, sulfoxidearyl, sulfoxideheterocyclyl, sulfoxideheteroaryl, sulfoxideacyl, sulfoxidearalkyl, sulfonylalkyl, sulfonylalkenyl, sulfonylalkynyl, sulfonylcarbocyclyl, sulfonylaryl, sulfonylheterocyclyl, sulfonylheteroaryl, sulfonylacyl, sulfonylaralkyl, sulfonamidoalkyl, sulfonamidoalkenyl, sulfonamidoalkynyl, sulfonamidocarbocyclyl, sulfonamidoaryl, sulfonamidoheterocyclyl, sulfonamidoheteroaryl, sulfonamidoacyl, sulfonamidoaralkyl, nitroalkyl, nitroalkenyl, nitroalkynyl, nitrocarbocyclyl, nitroaryl, nitroheterocyclyl, nitroheteroaryl, nitroacyl, nitroaralkyl, cyano, sulfate, phosphate, triarylmethyl, triarylamino, oxadiazole, and carbazole groups. Optional substitution may also be taken to refer to where a -CH ₂ - group in a chain or ring is replaced by a group selected from -O-, -S-, -NR ^a -, -C(O)- (i.e. carbonyl), -C(O)O- (i.e. ester), and -C(0)NR ^a - (i.e. amide), where R ^a is as defined herein.

Preferred optional substituents include alkyl, (e.g. Cj _-6 alkyl such as methyl, ethyl, propyl, butyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl), hydroxyalkyl (e.g. hydroxymethyl, hydroxyethyl, hydroxypropyl), alkoxyalkyl (e.g. methoxymethyl, methoxy ethyl, methoxypropyl, ethoxymethyl, ethoxyethyl, ethoxypropyl etc) alkoxy (e.g. C _1-6 alkoxy such as methoxy, ethoxy, propoxy, butoxy, cyclopropoxy, cyclobutoxy), halo, trifluoromethyl, trichloromethyl, tribromomethyl, hydroxy, phenyl (which itself may be further substituted e.g., by Ci _-6 alkyl, halo, hydroxy, hydroxyC _1-6 alkyl, Ci _-6 alkoxy, haloCi _-6 alkyl, cyano, nitro OC(O)C _1-6 alkyl, and amino), benzyl (wherein benzyl itself may be further substituted e.g., by Ci _-6 alkyl, halo, hydroxy, hydroxyCi _-6 alkyl, C _1-6 alkoxy, haloCi _-6 alkyl, cyano, nitro OC(O)Ci _-6 alkyl, and amino), phenoxy (wherein phenyl itself may be further substituted e.g., by Ci _-6 alkyl, halo, hydroxy, hydroxyCi _-6 alkyl, Ci _-6 alkoxy, haloCi _-6 alkyl, cyano, nitro OC(O)Ci _-6 alkyl, and amino), benzyloxy (wherein benzyl itself may be further substituted e.g., by Ci _-6 alkyl, halo, hydroxy, hydroxyCi _-6 alkyl, Ci _-6 alkoxy, haloC] _-6 alkyl, cyano, nitro OC(O)Ci _-6 alkyl, and amino), amino, alkylamino (e.g. Ci _-6 alkyl, such as methylamino, ethylamino, propylamino etc), dialkylamino (e.g. Ci _-6 alkyl, such as dimethylamino, diethylamino, dipropylamino), acylamino (e.g. NHC(O)CH ₃ ), phenylamino (wherein phenyl itself may be further substituted e.g., by C _1-6 alkyl, halo, hydroxy, hydroxyCi _-6 alkyl, Ci _-6 alkoxy, haloCi _-6 alkyl, cyano, nitro OC(O)Ci _-6 alkyl, and amino), nitro, formyl, -C(O)-alkyl (e.g. Ci _-6 alkyl, such as acetyl), O-C(O)-alkyl (e.g. Ci- ₆ alkyl, such as acetyloxy), benzoyl (wherein the phenyl group itself may be further substituted e.g., by Ci _-6 alkyl, halo, hydroxy hydroxyCi _-6 alkyl, C) _-6 alkoxy, ImIoC _1-6 alkyl, cyano, nitro OC(O)C i _-6 alkyl, and amino), replacement of CH ₂ with C=O, CO ₂ H, C0 ₂ alkyl (e.g. Cμ ₆ alkyl such as methyl ester, ethyl ester, propyl ester, butyl ester), C0 ₂ phenyl (wherein phenyl itself may be further substituted e.g., by Ci _-6 alkyl, halo, hydroxy, hydroxyl Ci _-6 alkyl, Ci _-6 alkoxy, halo Ci _-6 alkyl, cyano, nitro OC(O)Ci _-6 alkyl, and amino), CONH ₂ , CONHphenyl (wherein phenyl itself may be further substituted e.g., by Ci _-6 alkyl, halo, hydroxy, hydroxyl Ci _-6 alkyl, Ci _-6 alkoxy, halo Ci _-6 alkyl, cyano, nitro OC(O)Ci _-6 alkyl, and amino), CONHbenzyl (wherein benzyl itself may be further substituted e.g., by C _1-6 alkyl, halo, hydroxy hydroxyl C _1-6 alkyl, C _1-6 alkoxy, halo C _1-6 alkyl, cyano, nitro OC(O)Cj _-6 alkyl, and amino), CONHalkyl (e.g. Cj _-6 alkyl such as methyl ester, ethyl ester, propyl ester, butyl amide) CONHdialkyl (e.g. Ci _-6 alkyl) aminoalkyl (e.g., HN Ci _-6 alkyl-, Ci _-6 alkylHN-C _1-6 alkyl- and (Ci _-6 alkyl) ₂ N-C _]-6 alkyl-), thioalkyl (e.g., HS Ci _-6 alkyl-), carboxyalkyl (e.g., HO ₂ CCj _-6 alkyl-), carboxyesteralkyl (e.g., Ci _-6 alkylθ ₂ CCi _-6 alkyl-), amidoalkyl (e.g., H ₂ N(O)CCi _-6 alkyl-, H(Cj _-6 alkyl)N(O)CCi _-6 alkyl-), formylalkyl (e.g., OHCCi _-6 alkyl-), acylalkyl (e.g., C _)-6 alkyl(O)CCi _-6 alkyl-), nitroalkyl (e.g., O ₂ NCi _-6 alkyl-), sulfoxidealkyl (e.g., R(O)SCi _-6 alkyl, such as Ci _-6 alkyl(O)SCi _-6 alkyl-), sulfonylalkyl (e.g., R(O) ₂ SCi _-6 alkyl- such as Cj _-6 alkyl(O) ₂ SC _{1 -6} alkyl-), sulfonamidoalkyl (e.g., ₂ HRN(O)SCi- ₆ alkyl, H(Ci _-6 alkyl)N(O)SCi _-6 alkyl-), triarylmethyl, triarylamino, oxadiazole, and carbazole.

Unless otherwise stated, reference to molecular weight herein is intended to be a number average molecular weight as determined by gel permeation chromatography (GPC).

The invention will now be described with reference to the following non-limiting examples:

EXAMPLES

Example 1 - Surface initiated polymerisation of acrylamide brushes on an electrospun membrane composed of a blend of polystyrene and a copolymer containing carboxylic acid moieties and iniferter moieties.

Part A: Synthesis of a Poly(acrylic acid-co-diethyl-dithiocarbamic acid 4-vinyl-benyl ester) copolymer.

Poly(acrylic acid-co-diethyl-dithiocarbamic acid 4-vinyl-benyl ester) copolymer was synthesized according to Example 3 in WO2008/019450 Al which for convenience is reproduced directly below. Acrylic acid (3.0 g, 4.16xlO ^"2 mol, anhydrous, Fluka) was dissolved in 6 mL of dimethylformamide (DMF) (BDH chemicals), followed by removal of the inhibitor by passage of the solution through a column containing Inhibitor Remover (Aldrich). To the acrylic acid solution was added 1.1 g of diethyl-dithiocarbamic acid 4-vinyl-phenyl ester (4.38x10 ^"3 mol) (from Example 2 - see below in Example 2 of the present application) and 150 mg of AIBN, following which the solution was purged with nitrogen for 10 min and sealed. Heating overnight at 60 ^° C resulted in the formation of an opaque, viscous gel which was diluted by further addition of 20 mL of DMF. The solution containing the copolymer was then dialysed (Spectrum Spectra/Por 1 molecular porous membrane tubing, MW cutoff 6000-8000) against DMF overnight. The DMF was changed twice during dialysis. The contents of the dialysis tube were then transferred to a flask and made up to a final volume of 50 mL.

The final poly(acrylic acid-co-diethyl-dithiocarbamic acid 4-vinyl-benzyl ester) copolymer (Pl) was characterised by quantitative ¹³ C NMR. ( ¹³ C NMR (DMFH ₇ / DMFD ₇ , 500 MHz; δ 10.7, 11.4, 32.7, 39.78, 40.66, 41.01 , 41.44, 46.03, 48.59, 127.41 , 128.61 , 133.5, 142.6, 169.7 (C=O), 171.55 (C=O), 173.79 (C=O), 175.67 (C=O), 193.66 (C-S)). The relative proportions of diethyl-dithiocarbamic acid 4-vinyl-ρhenyl ester to acrylic acid residues were obtained by integrating the peaks corresponding to the C=S (from the diethyl- dithiocarbamic acid 4-vinyl-phenyl ester) and C=O (from the acrylic acid) residues. This procedure gave a ratio of 1.0: 10.7 for C=S:C=O which corresponded to a polymer containing 8.5:91.5 mol% diethyl-dithiocarbamic acid 4- vinyl-phenyl esteπacrylic acid.

A solution containing 12% (w/v) polystyrene (MW 230,000) and 6% (w/v) poly(acrylic acid-co-diethyl-dithiocarbamic acid 4-vinyl-benyl ester) copolymer, 4 μM of dodecyl trimethyl ammonium bromide (DTAB, 99%) and 1.605 nM fluorescein- 5 -isothiocyanate (FITC, isomer I, 90%) was made up in dimethylformamide (DMF analytical grade). AU reagents were supplied from Sigma-Aldiϊch and used without further purification. The solution was transferred to a plastic syringe fitted with a copper electrode, which was connected to a high voltage generator of a custom built electrospinning unit. The syringe was kept at a distance of 10 cm from the aluminium cathode maintained at -5 kV. Electrospinning of the solution under voltages of 20 and 30 IcV produced a highly porous and fibrous membrane. The average fibre diameter determined by SEM (S570 Hitachi) were 1.9 ± 0.4 μm and 2.1 ± 0.8 μm for the 20 and 30 kV electrospinning voltages respectively.

Presented in Table 1 is an XPS elemental analysis of the membrane surfaces at different electrospinning voltages. It was observed that increasing the electrospinning voltage increased the amount of iniferter surface moieties presented (represented by increased sulphur content), and membranes presented in this example were produced at 20 and 30 kV respectively.

Table 1 : Elemental composition determined via XPS analysis of polystyrene membrane and polystyrene blended with poly(acrylic acid-co-diethyl-dithiocarbamic acid 4-vinyl- benyl ester) membrane, electrospun at 20 and 30 IcV.

Part B: Graft Polymerisation of Acrylamide Monomer from an Electrospun Polystyrene 3D Scaffold Containing Carboxylic Acid Moieties and Iniferter Moieties

A 0.704 mol acrylamide monomer solution (Sigma-Aldrich) was prepared in Milli-Q ,TM water for later use. The electrospun membranes were cut into ~lcm ² pieces and wetted with a few drops of ethanol (Merck), then rinsed at least 4 times with Milli-Q™ water. Excess water was removed until the membranes were just wetted, and membranes were placed in individual wells. The assembly was placed in a custom built stainless steel cell fitted with a quartz glass top and taps for gas purging. The cell and acrylamide monomer solution were transferred to a nitrogen purged glove box for oxygen removal for 30 minutes, after which the acrylamide solution was dispensed to each well. The cell was sealed to be air tight within the glovebox, then removed and placed beneath an Elector-lite EL-C800 UV/Visible light source at a distance of 10 cm. UV polymerisation was carried out for 30 minutes (approx. 50mWcm ^"2 intensity). The membranes were removed from the cell and rinsed four times with Milli-Q™ water and soaked overnight. Then the membranes were washed another two times with Milli-Q ^τ water and dried for XPS analysis.

Presented in Table 2 are the elemental compositions calculated from the surface composition of the samples as determined by XPS analysis. It was evident that the grafting procedure resulted in a polyacrylamide coating (increased N%) on the membranes containing the iniferter moiety, but not for the membrane containing only polystyrene. This demonstrated that the UV grafting process is dependent on the presence of the iniferter moiety in the electrospun membrane. Representative high resolution C Is XPS spectra are presented in Figure 1, compared to a pure polystyrene membrane. The C Is spectra contained a component due to the presence of amide functionality that was not present in the spectra obtained for the polystyrene membrane.

Table 2: Elemental composition of electrospun membrane determined via XPS analysis of polystyrene membranes and polystyrene blended with the poly(acrylic acid-co-diethyl- dithiocarbamic acid 4-vinyl-benyl ester) copolymer membranes electrospun at 20 and 30 IcV after UV treatment with acrylamide monomer solution for 30 minutes.

Example 2 - Surface initiated polymerisation of acrylamide or glucoside containing brushes on an electrospun membrane composed of a blend of polystyrene and a copolymer containing styrene and iniferter moieties.

Part A: Synthesis of copolymer containing styrene and iniferter moieties An iniferter molecule, diethyl-dithiocarbamic acid 4-vinyl-phenyl ester was synthesized according to Example 2 in WO2008/019450 Al which for convenience is repeated directly below.

A solution of sodium diethyldithiocarbamate trihydrate (3.5 g, 1.55xlO ^"2 mol) in 20 mL of ethanol was added to a flask equipped with a stirrer, dropping funnel and a reflux condenser. To this solution was added a solution of 4-vinylbenzyl chloride (3.0 g, 1.96x10 ^"2 mol) and ethanol (5 mL), dropwise, over a period of 0.5 h at a temperature of 0 ^° C. The resultant solution was stirred at room temperature for 24 h before pouring into a large volume of water and extracting with diethyl ether. The ether phase was washed three times with water, dried over sodium sulphate, before finally removing the diethyl ether by evaporation. The residue was recrystallised three times from methanol, giving a yield of 2.6 grams (83 %). ¹ H NMR (CDCI ₃ ) 57.36 (s, 4H, C ₆ H ₄ ), 6.70 (dd, J = 11.6 and 17.5 Hz, IH, CH=CH ₂ ), 5.73 (d, J = 17.5 Hz, 1 H, CH=CH ₂ ), 5.24 (d, J = 11.5 Hz ₅ 1 H, CH=CH ₂ ), 4.54 (s, 2H, CH ₂ S), 4.04 (q, J = 7.3 Hz, 2H, NCH ₂ ), 3.73 (q, J = 6.6 Hz, 2H NCH ₂ ), 1.19 (t, J = ca.7.0 Hz, 6H CH ₂ CH ₃ ).

Deinhibited styrene monomer (99%, 1.5g, 1.5 x 10-2 mol, Sigma-Aldrich) and the iniferter monomer (0.42g, 1,5 x 10-3 mol) were mixed with 0.83 of chloroform (Merck) and 4.3mg of azobisisobutyronitrile (AIBN). The solution was vacuum degassed for 10 minutes, then purged with dry nitrogen for 5 minutes. The degassing and purging cycle was repeated once more. The solution was then stoppered by a rubber septum, purged with nitrogen gas for a further 10 minutes and stirred overnight heated at 60°C.

The next day the solution was diluted with 4mL of distilled dichloromethane (Merck) and placed in a dropping funnel. The polymer was precipitated by adding the solution dropwise to a large excess of methanol (Merck). The methanol/precipitate mixture was filtered, and the precipitate was redissolved in 5mL of dichloromethane. After re-filtering, the polymer was dried overnight in a vacuum oven that has been degassed and nitrogen purged twice for 20 minutes at 3O ⁰ C. Analysis by GPC showed a Mn of 5.6 x 10 ⁴ Da and Mw of 9.6 x l0 ⁴ Da.

Part B: Production of a fibrous membrane containing styrene and iniferter moieties

A solution containing 12% (w/v) polystyrene (MW 230,000), 1.7% (w/v) of the poly(styrene-co-diethyl-dithiocarbamic acid 4-vinyl-phenyl ester), 4 μM of dodecyl trimethyl ammonium bromide (DTAB, 99%) and 1.605 nM fluorescein-5-isothiocyanate (FITC, isomer I, 90%) Was made up in DMF (analytical grade). All reagents were supplied from Sigma-Aldrich and used without further purification. The solution was transferred to a plastic syringe fitted with a copper electrode, which was connected to a high voltage generator of a custom built electrospinning unit. The syringe was kept at a distance of 10 cm from the aluminium cathode maintained at -5 IcV. Electrospinning of the solution under high voltage produced a highly porous and fibrous membrane. The average fibre diameter determined by a SEM S570 (Hitachi) was 300 ± 1 lOnm.

Presented in Table 3 is an XPS elemental analysis of the membrane surfaces produced at 30 kV.

Table 3: Elemental composition of electrospun membrane determined via XPS analysis of polystyrene membrane and polystyrene blended with poly(styrene-co-diethyl- dithiocarbamic acid 4-vinyl-phenyl ester) electrospun at 30 kV.

Part C: Graft Polymerisation of Acrylamide or Glucoside Monomer from an Electrospun Polystyrene 3D Membrane Containing Styrene and Iniferter Moieties

Graft polymerisation of acrylamide or 2-methacryloxyethyl glucoside monomer was performed on the membranes. A 0.704 M acrylamide monomer solution (Sigma-Aldrich) and a 0.17 M monomer solution of 2-methacryloxyethyl glucoside (Polysciences inc.) were prepared in Milli-Q™ water for later use. Membranes were cut into ~lcm ² pieces and wetted with a few drops of ethanol (Merck), then rinsed at least 4 times with Milli-Q™ water. Excess water was removed until the membranes were just wetted and were placed in individual wells. The assembly was placed in a custom built stainless steel cell fitted with a quartz glass top and taps for gas purging. The cell and acrylamide or 2- methacryloxyethyl glucoside monomer solutions were transferred to a nitrogen purged glove box for oxygen removal for 30 minutes, after which the acrylamide or 2- methacryloxyethyl glucoside solution was dispensed to each well. The cell was sealed to be air tight within the glovebox, then removed and placed beneath an Elector-lite EL-C800 UV/Visible light source at a distance of 10 cm. UV polymerisation was carried out for 30 minutes (approx. 30 mWcm ^"2 intensity). The membranes were removed from the cell and rinsed four times with Milli-Q™ water and soaked overnight. Then the membranes were washed another two times with Milli-Q™ water and dried for XPS analysis.

Presented in Tables 4 and 5 are the elemental compositions calculated from the surface composition of the samples as determined by XPS analysis. Here we may see that the grafting procedure resulted in a polyacrylamide coating (increased N%) on membranes containing the iniferter moiety, but not for the membrane containing only polystyrene (Table 4). Likewise, a greater increased in 0% was evident for glucoside grafting with iniferter (Table 5). This demonstrated that the UV grafting process is dependent on the presence of the iniferter moiety in the electrospun membrane. Representative high resolution C Is XPS spectra are presented in Figures 2 & 3, compared to the pure polystyrene membrane. In both spectra, compared to the control, the iniferter containing membrane showed additional components due to the presence of C-N or C-O and C=O bonds.

Table 4: Elemental composition of electrospun membrane determined via XPS analysis of the polystyrene membrane and polystyrene blended with poly(styrene-co-diethyl- dithiocarbamic acid 4-vinyl-phenyl ester) membranes electrospun at 30 kV after UV treatment with acrylamide monomer solution for 30 minutes.

Table 5: Elemental composition of electrospun membrane determined via XPS analysis of the polystyrene and polystyrene blended with poly(styrene-co-diethyl-dithiocarbamic acid 4-vinyl -phenyl ester) membranes electrospun at 30 kV after UV treatment with glucoside monomer solution for 30 minutes.

Example 3 - Surface initiated polymerisation of acrylamide brushes on an electrospun membrane composed of a blend of polystyrene and a lower molecular weight polystyrene containing a RAFT end group.

Part A: Electrospinning of a Polystyrene 3D Membrane Containing RAFT moieties.

A polymer with a molecular weight of 5800 was synthesised in house, the chemical structure of which is shown below:

This RAFT terminated polymer was synthesised as follows. Trithiocarbonic acid butyl ester 4-vinyl-benzyl ester was made in the following manner. Butanethiol (0.75 niL) and carbon disulfide (0.84 mL) were added to chloroform (20ml) under N ₂ at room temperature. Triethylamine (1.9 mL) was then added dropwise and the solution was let stir for 20 minutes. 4-Chloromethyl-benzoic acid 2-allyloxy-ethyl ester (1.3g) in chloroform was added dropwise to the reaction. The reaction was worked up after 3 days by washing with water, drying with magnesium sulfate and evaporation of the solvent to give 2.2g of yellow oil. NMR spectroscopy confirmed the structure of the product. ¹ H NMR 0.9 (t), 1.30(mult.) , 1.65 (mult.), 3.35 (t), 3.80 (t), 4.1 (d), 4.5 (t), 4.6 (s), 5.2-5.4 (mult), 5.8-6.0 (mult)., 7.4 (d), 8.0 (d) ppm. ¹³ C NMR 13.6, 22.1, 30.0, 37.0, 40.6, 64.2, 68.0, 72.2, 117.4,129.2, 129.4, 130.0, 134.5, 140.9, 166.1, 223.0 ppm.

Trithiocarbonic acid butyl ester 4-vinyl-benzyl ester (410mg) , styrene (5g) were added together, and degassed by the freeze-pump-thaw method prior to being sealed in a gas tight vessel. The mixture was heated at 110 C for 5 days. The polymer was collected dissolving the reaction in benzene (1OmL) and adding it dropwise to methanol (75OmL). The precipitate was collected as a yellow powder (4.8g). This material had a molecular weight of 5800g/mole. NMR clearly showed the endgroups (butyl trithiocarbonate and alylloxy ethanol) as mostly unresolved singlets at 0.90, 3.2, 3.8, 4.1, 4.5, 5.1-5.5 (multiplet), 5.8-6.1

(multiplets) ppm in addition to those peaks expected from polystyrene.

A solution comprising 12.5 (w/v) of this polymer, 12.5% (w/v) polystyrene (MW 230,000) and 4 μM of dodecyl trimethyl ammonium bromide (DTAB, 99%) was made up in DMF (analytical grade). All reagents were supplied from Sigma-Aldrich and used without further purification. The solution was transferred to a plastic syringe fitted with a copper electrode, which was connected to a high voltage generator of a custom built electrospinning unit. The syringe was kept at a distance of 10 cm from the aluminium cathode maintained at -5 IcV. Electrospinning of the solution under voltages of either 20 or 30 IcV produced a highly porous and fibrous membrane. The average fibre diameter determined by a SEM S570 (Hitachi) was 1.4 ± 0.5 μm.

Presented in Table 6 is an XPS elemental analysis of the membrane surfaces at different electrospinning voltages. The increase of oxygen and sulphur percentage corresponded with increasing electrospinning voltage. Table 6: Elemental composition of electrospun membranes determined via XPS analysis of polystyrene and polystyrene blended with RAFT end terminated polystyrene, electrospun at 20 and 3O kV.

Part B: Graft Polymerisation of Acrylamide Monomer from Electrospun Polystyrene Scaffold Containing RAFT moieties.

A 0.704 mol acrylamide monomer solution (Sigma- Aldrich) was prepared in Milli-Q ⁷ water for later use. Electrospun membranes were cut into ~lcm ² pieces and wetted with a few drops of ethanol (Merck), then rinsed at least 4 times with Milli-Q™ water. Excess water was removed until the membranes were just wetted, and membranes were placed in individual wells. The assembly was placed in a custom built stainless steel cell fitted with a quartz glass top and taps for gas purging. The cell and acrylamide monomer solution were transferred to a nitrogen purged glove box for oxygen removal for 30 minutes, after which the acrylamide solution was dispensed to each well. The cell was sealed to be air tight within the glovebox, then removed and placed in a vacuum oven. The oven was degassed to 200 mbar, then purged with nitrogen continuously at 50°C for 68 hours. The membranes were removed from the cell and rinsed four times with Milli-Q™ water and soaked overnight. Then the membranes were washed another two times with Milli-Q™ water and dried for XPS analysis.

Presented in Table 7 are the elemental compositions determined from the surface of the membranes as determined by XPS analysis. A poly(acrylamide) coating was evident (incr eased N%) on membranes containing the RAFT moiety. Further evidence that the poly(acrylamide) grafting reaction was successful was obtained from high resolution XPS analysis in Figure 4. For the RAFT moiety incorporated sample, high resolution C Is spectra contained a component due to the presence of amide functionality that was not present in the spectra obtained before grafting.

Table 7: Elemental composition of electrospun membrane determined via XPS analysis of polystyrene only membrane and blended copolymer membranes with incorporation of the RAFT moiety produced at 20 and 30 kV after reaction with acrylamide monomer solution for.

Example 4 Graft polymerisation of acrylamide and hydroxyethylacrylate monomer from electrospun polystyrene blended with a polystyrene copolymer containing RAFT moieties.

Part A: Synthesis of a styrene and butyl 4-vinylbenzyl trithiocarbonate copolymer.

Butyl 4-vinylbenzyl trithiocarbonate monomer containing the reverse additional fragmentation polymerisation (RAFT) moiety (see structure directly below) was pre- synthesised and used as outlined below:

This monomer was synthesised as follows. Butanethiol (1.4ml, 1.179g, O.Olβmol, lm.e) and carbondisulfide (1.87ml, 2m.e) were added to chloroform (32ml) under N ₂ at romm temperature. Triethylamine (3.21ml, 3m.e) was then added dropwise. The reaction was stirred for Ih, then chloromethylstyrene (1.48ml, 0.8m.e) in chloroform (5ml) was added dropwise. The reaction was stirred o/n. The reaction was then washed with water (2x30ml), then with dil. HCl (50ml), then dried with MgSO ₄ . The reaction was evaporated to dryness. Excess butanethiol was then removed by bubbling a stream of nitrogen through the product overnight. The desired product was obtained as a clear orange oil, 1.78g, 49%. NMR (400 MHz, CDCl ₃ ) δ 0.96 (t, J=7.6Hz, 3H ₃ -CH ₃ ), 1.45 (m, 2H, CH ₂ -CR ₃ ), 1-70 (m, 2H, CH ₂ CH ₂ CH ₃ ), 3.39 (t, J=7.2Hz, 2H, -CH ₂ CH ₂ S), 4.61 (s, 2Η, CH ₂ -aromatic), 5.26 (d, J=10.8Ηz, CH=CH-aromatic), 5.75 (d, J=20Hz, IH, CH=CH-aromatic), 6.70 (m,lH, =CH- aromatic), 7.30-7.38 (m,4Η, aromatic) ppm. ¹³ C NMR (CDCl ₃ , 200 MHz) δ 13.6, 22.1, 30.0, 36.8, 41.1, 114.2, 126.5, 129.4, 134.6, 136.3, 137.1, 223.8 ppm.

For copolymerisation, 0.8137g of the trithiocarbonate monomer (2.9 x 10 ^"3 mol) was blended with 9.7Og (9.31 x 10 ^'2 mol) of deinhibited styrene monomer (99%, Sigma- Aldrich), 3mL of toluene (Merck) and 29mg of azobisisobutyronitrile (AIBN). The solution was vacuum degassed for 10 minutes, then purged with dry nitrogen for 5 minutes. The degas and purge cycle was repeated once more. The solution was maintained at 65 ⁰ C and stirred overnight. The next day the solution was diluted with 8mL of distilled dichloromethane (Merck) and placed in a dropping funnel. The polymer was precipitated by adding the solution dropwise to a large excess of methanol (Merck). The methanol and precipitated polymer were filtered and dried overnight in a vacuum oven that has been degassed and nitrogen purged twice for 20 minutes at 30 ⁰ C.

Part B: Electrospinning of the copolymer blended membrane.

The RAFT containing copolymer was blended with pure polystyrene (MW 230,000) in a 4:5 ratio. A 12% (w/v) solution of the blend was mixed with 4 μM of dodecyl trimethyl ammonium bromide (DTAB, 99%) and made up in DMF (analytical grade). AU reagents were supplied from Sigma-Aldrich and used without further purification. The solution was transferred to a plastic syringe fitted with a copper electrode, which was connected to a high voltage generator of a custom built electrospinning unit. The syringe was kept at a distance of 10 cm from the aluminium cathode maintained at -5 kV. Electrospinning of the solution under a voltage of 20 kV produced a highly porous and fibrous membrane. The average fibre diameter determined by a SEM S570 (Hitachi) was 2.1 ± 0.6 μm.

Presented in Table 8 is an XPS elemental analysis of the membrane surfaces.

Table 8: Elemental composition of electrospun membranes determined via XPS analysis of polystyrene membrane and polystyrene blended with a polystyrene copolymer containing RAFT moieties electrospun at 20 kV.

Part C: Graft Polymerisation of Acrylamide and Hydroxyethylacrylate Monomer from Electrospun Polystyrene Scaffold Containing RAFT Moieties. A 0.704 M acrylamide monomer solution (Sigma-Aldrich), and a 0.365 M hydroxyethylacrylate (HEA) monomer solution were prepared in Milli-Q™ water for later use. Membranes were cut into ~lcm ² pieces and wetted with a few drops of ethanol (Merck), then rinsed at least 4 times with Milli-Q™ water. Excess water was removed until the membranes were just wetted, and membranes were placed in individual wells of a 12-well plate (Nunc). The assembly was placed in a custom built stainless steel cell fitted with a quartz glass top and taps for gas purging. The cell and monomer solutions were transferred to a nitrogen purged glove box for oxygen removal for 30 minutes, after which the monomer solutions were gently purged with nitrogen for 10 minutes. Thermal initiator 2,2'- azobis(2-amidino-propane) dihydrochloride (Wako) was added to the solution to a concentration of 0.5mg/mL, and 2mL of monomer solution was dispensed to each well. The cell was sealed to be air tight within the glovebox, then removed and placed in a vacuum oven. The oven was degassed to 200 mbar, then purged with nitrogen twice for 20 minutes. The reaction was left at 50 ⁰ C for 70 hours, after which the membranes were removed from the cell and rinsed four times with Milli-Q™ water and soaked overnight. Membranes were washed another two times with Milli-Q™ water and dried for XPS analysis.

Presented in Table 9 and 10 are the elemental compositions calculated from the surface composition of the samples as determined by XPS analysis. Here we may see that compared to Table 8, the grafting procedure via RAFT chemistry resulted in a polyacrylamide coating (increased N%) on membranes containing the RAFT moiety, demonstrating the functionality of the immobilised RAFT moieties on the electrospun surfaces. Membranes without the RAFT moiety only displayed very limited grafting of the monomer. For HEA (Table 9), similar trends are observed in the change in %O, with much greater oxygen being present on the surface for membranes with RAFT moieties. Table 9: Elemental composition of electrospun membranes (20 IcV) after RAFT-mediated grafting with acrylamide.

'Table 10: Elemental composition of electrospun membranes (2OkV) after RAFT-mediated grafting with HEA.

Further evidence that the grafting reactions were successful was obtained from high resolution XPS analysis in Figures 5 and 6. Samples with RAFT moieties demonstrated a distinct component in high resolution CIs spectra due to additional C-N or C=O components compared to controls.

Example 5 - Preparation of polyacrylamide and poly(hydroxyethylacrylate) graft coatings on electrospun poly(styrene-co-butyl 4-vinylbenzyl trithiocarbonate) membranes.

Part A: Synthesis of a copolymer containing styrene and 4-chloromethylstyrene moieties.

Deinhibited styrene monomer (99%, 9.0g, 8.6 x 10 ^"2 mol, Sigma- Aldrich) and 1- (chloromethyl)-4-vinylbenzene (CMVB, 1.47g, 9.6 x 10-3 mol, Sigma- Aldrich) were mixed with 4.5mL of Toluene (Merck) and 26mg of azobisisobutyronitrile (AIBN). The solution was vacuum degassed for 10 minutes, then purged with dry nitrogen for 5 minutes. The degas and purge cycle was repeated once more. The solution was then stoppered by a rubber septum, purged with nitrogen gas for a further 10 minutes and stirred overnight heated at 60°C.

The next day the solution was diluted with 8mL of distilled dichloromethane (Merck) and placed in a dropping funnel. The polymer was precipitated by adding the solution dropwise to a large excess of methanol (Merck). The methanol/precipitate mixture was filtered, and the precipitate was redissolved in 1OmL of dichloromethane. After re- filtering, the polymer was dried overnight in a vacuum oven that has been degassed and nitrogen purged twice for 20 minutes at 30°C.

Analysis of the copolymer by GPC found Mn of 81900 and Mw 132500 Da.

Part B: Synthesis of Butyltrithiocarbamate Anion

Carbon disulfide (0.887g, 1.6 x 10 ^"2 mol, Univar) and butanethiol (0.72g, 0.008 mol, Ajax Chemicals) were added to HmL of chloroform (Univar) in a round bottom flask. The flask was sealed with a rubber septum and purged with nitrogen. Triethylamine (1.02g, l.OxlO ^"2 mol, Sigma- Aldrich) was added dropwise to this solution. The reaction mixture was left stirring overnight at room temperature.

Part C: Synthesis of a Copolymer Containing styrene and Reversible Addition- Fragmentation Chain Transfer Agent Moieties (RAFT Copolymer)

About 3.5g of the copolymer was added to the butyltrithiocarbamate salt solution. The reaction mixture was stirred at room temperature for two hours before being transferred to a dialysis membrane (Spectrum SpectraPor 1, molecular weight cut off 6-8 kDa) and dialysed against chloroform for 4 days with multiple changes of chloroform. The polymer solution inside the dialysis tubing was yellow in colour. The colour was maintained over the period of dialysis. A sample of this polymer solution was removed for quantitative IH NMR analysis: which showed unresolved singlets 0.95, 1.1, 1.4, 1.7, 2-5-2.7 (multi), 4.55 (s), 6.1-7.5 (mult). The mol ratio of styrene to butyl 4-vinylbenzyl trithiocarbonate in the copolymer was determined to be approximately 4.4: 1.

Part D: Electrospinning of the copolymer membrane.

The polymer solution produced (in chloroform solvent) was transferred to a plastic syringe fitted with a copper electrode, which was connected to a high voltage generator of a custom built electrospinning unit. The syringe was kept at a distance of 10 cm from the aluminium collector maintained at -5 kV. Electrospinning of the solution under a voltage of 25 IcV produced a highly porous and fibrous membrane. The average fibre diameter determined using a SEM S570 (Hitachi) was 600 ± 200 nm.

Presented in Table 11 is an XPS elemental analysis of the membrane surfaces at different electrospinning voltages. A membrane of 12% polystyrene was prepared for comparison.

Table 11 : Elemental composition of electrospun membrane determined via XPS analysis of polystyrene membranes and poly(styrene-co-butyl 4-vinylbenzyl trithiocarbonate) membranes electrospun at 25 IcV.

Part E: Graft Polymerisation of Acrylamide and Hydroxyethylacrylate Monomer from Electrospun Polystyrene Membrane Containing RAFT Moieties

A 0.47 M acrylamide monomer solution (Sigma-Aldrich), and a 0.36 M hydroxyethylacrylate (HEA) monomer solution were prepared in Milli-Q™ water for later use. Membranes were cut into ~-lcm ² pieces and wetted with a few drops of ethanol (Merck), then rinsed at least 4 times with Milli-Q™ water. Excess water was removed until the membranes were just wetted, and membranes were placed in individual wells of a 12-well plate (Nunc). The assembly was placed in a custom built stainless steel cell fitted with a glass top and taps for gas purging. The cell and monomer solutions were transferred to a nitrogen purged glove box for oxygen removal for 30 minutes, after which the monomer solutions were gently purged with nitrogen for 10 minutes. Thermal initiator 2,2'- azobis(2-amidino-propane) dihydrochloride (Wako) was added to the solution to a concentration of 0.5mg/mL, and 2mL of monomer solution was dispensed to each well. The cell was sealed to be air tight within the glovebox, then removed and placed in a vacuum oven. The reaction was left at 5O ⁰ C for 70 hours with continuous nitrogen flush through the oven, after which the membranes were removed from the cell and rinsed four times with Milli-Q™ water and soaked overnight. Membranes were washed another two times with Milli-Q™ water and dried for XPS analysis.

Presented in Table 12 and 13 are the elemental compositions calculated from the surface composition of the samples as determined by XPS. Here we may see that compared to table 11 , the grafting procedure via RAFT chemistry resulted in a polyacrylamide coating (increased N%, Table 12) on membranes containing the RAFT moiety, demonstrating the functionality of the immobilised RAFT moieties on the electrospun surfaces. Membranes without the RAFT moiety only displayed very limited grafting of the monomer. For HEA (Table 13), similar trends are observed in the change in %O, with greater amounts of oxygen being present on the surface for membranes with RAFT moieties.

Table 12: Elemental composition of membranes electrospun at 2OkV after RAFT-mediated grafting with acrylamide.

Table 13: Elemental composition of membranes electrospun at 2OkV after RAFT-mediated grafting with HEA.

Further evidence that the grafting reactions were successful was obtained from high resolution XPS analysis in Figures 7 and 8. Samples with RAFT moieties demonstrated a distinct component in high resolution CIs spectra due to additional C-N or C=O components compared to controls.

Example 6 - Preparation of polyacrylamide and poly(ethyleneglycomethacrylate) Graft Coatings on Electrospun poly(styrene-co-butyl 4-vinylbenzyl trithiocarbonate membranes.

Part A: Synthesis of a copolymer containing styrene and 4-chloromethylstyrene moieties Deinhibited styrene monomer (99%, 22.5 g, 0.21 mol, Sigma- Al drich) and 1- (chloromethyl)-4-vinylbenzene (CMVB, 3.6967g, 2.4 x 10 ^'2 mol, Sigma-Aldrich) were mixed with 10.OmL of toluene (Merck) and 55mg of azobisisobutyronitrile (AIBN). The solution was vacuum degassed for 20 minutes, then purged with dry nitrogen for 2 minutes. The degassing and purging cycle was repeated once more. The solution was then stoppered by a rubber septum, purged with nitrogen gas for a further 10 minutes and stirred overnight heated at 60°C.

The next day the solution was diluted with 5mL of toluene and placed in a dropping funnel. The polymer was precipitated by adding the solution dropwise to a large excess of methanol (Merck). The polymer was dried overnight in a vacuum oven that has been degassed and nitrogen purged twice for 20 minutes at 3O ⁰ C.

Analysis of the monomer by GPC found a Mn of 90,226 and a Mw of 152,437 Da.

Part B: Synthesis of Butyltrithiocarbamate Anion. Carbon disulfide (0.887g, 1.6 x 10-2 mol, Univar) and butanethiol (0.72g, 0.008 mol, Ajax Chemicals) were added to 1 ImL of chloroform (Univar) in a round bottom flask. The flask was sealed with a rubber septum and purged with nitrogen. Triethylamine (1.02g, 1.0x10-2 mol, Sigma-Aldrich) was added dropwise to this solution. The reaction mixture was left stirring overnight at room temperature.

Part C: Synthesis of a Copolymer Containing Styrene and Reversible Addition- Fragmentation Chain Transfer Agent Moieties (RAFT Copolymer).

The copolymer sample produced in Part A (3.5g) was added to the butyltrithiocarbamate salt solution formed in Part B. The reaction mixture was stirred at room temperature for two hours before being transferred to a dialysis membrane (Spectrum SpectraPor 1, molecular weight cut off 6-8 kDa) and dialysed against chloroform for 4 days with multiple changes of chloroform. The polymer solution inside the dialysis tubing was yellow in colour. The colour was maintained over the period of dialysis. A sample of this polymer solution was removed for quantitative ¹³ C NMR (DMFH ₇ /DMFD ₇ , 500 MHz; 612.97, 18.25, 30.76-31.23, 36.30, 40.16-41.15, 57.95, 125.51-128.71 (C=C), 145.01 (C=C), 162.35, 206.80, 223.5-223.6 (C=S)). The relative proportions of butyl 4- vinylbenzyl trithiocarbonate to styrene were obtained by integrating the aromatic peaks at 145.01 ppm (C=C, from butyl 4-vinylbenzyl trithiocarbonate and styrene) and 223.5-223.6 ppm (C=S, from butyl 4-vinylbenzyl trithiocarbonate). This procedure gave a ratio of 1.0:6.71 which corresponded to a polymer containing 13: 87 mol% butyl 4-vinylbenzyl trithiocarbonate :styrene .

Part D: Electrospinning of the Polystyrene Blended with a Copolymer Containing Styrene and RAFT Moieties.

The polymer solution produced in Part C (in chloroform solvent) was blended with neat polystyrene (MW 230,000) in a 5:4 ratio to achieve 12%wt. solids, then transferred to a plastic syringe fitted with a copper electrode, which was connected to a high voltage generator of a custom built electrospinning unit. The syringe was kept at a distance of 10 cm from the aluminium collector plate maintained at -5 kV. Electrospinning of the solution under a voltage of 25 kV produced a highly porous and fibrous membrane. The average fibre diameter determined using a SEM S570 (Hitachi) was 250 ± 20 nm.

Part E: Graft Polymerisation of Acrylamide and Poly(ethylene glycol) methyl ether methacrylate Monomer from Electrospun Polystyrene Blended with a Copolymer Containing Styrene and RAFT moieties

A 0.42 M acrylamide monomer solution (Sigma- Aldrich), and a 8.9x10 ^'2 M poly(ethylene glycol) methyl ether methacrylate (PEGMA) monomer solution (Sigma- Aldrich, Mw -475 Da) were prepared in Milli-Q™ water for later use. Membranes were cut into ~lcm ² pieces and wetted with a few drops of ethanol (Merck), then rinsed at least 4 times with Milli-Q™ water. Excess water was removed until the membranes were just wetted, and membranes were placed in individual wells of a 24-well plate (Nunc). The assembly was placed in a custom built stainless steel cell fitted with a glass top and taps for gas purging. The cell and monomer solutions were transferred to a nitrogen purged glove box for oxygen removal for 30 minutes, after which the monomer solutions were gently purged with nitrogen for 10 minutes. Thermal initiator 2,2'- azobis(2-amidino-propane) dihydrochloride (Wako) was added to the solution to a concentration of 0.5mg/mL, and ImL of monomer solution was dispensed to each well. The cell was sealed to be air tight within the glovebox, then removed and placed in a vacuum oven. The reaction was left at 50°C for 72 hours while maintaining a nitrogen atmosphere in the oven. Subsequently the membranes were removed from the cell and rinsed four times with Milli-Q™ water and soaked overnight. Membranes were washed another two times with Milli-Q™ water and dried for XPS analysis. Presented in Table 14 is an XPS elemental analysis of the membrane surfaces. Here it may be observed that the RAFT-mediated grafting of acrylamide had increased the nitrogen content. Likewise, grafting of PEGMA on the membranes had resulted in increased oxygen content. Table 14: Elemental composition of electrospun membranes determined via XPS analysis of membrane composed of polystyrene blended with a copolymer containing styrene and RAFT moieties before and after RAFT-mediated grafting with acrylamide and PEGMA.

Sample C% 0% N% S%

Polystyrene blended with copolymer containing styrene 98.88 0.70 - 0.42 and RAFT moiety

Polystyrene blended with copolymer containing styrene 86.0 7.00 6.62 0.35 and RAFT moiety grafted with polyacrylamide

Polystyrene blended with copolymer containing styrene 88.7 10.86 - 0.41 and RAFT moiety grafted with polyPEGMA

Further evidence that the grafting reactions were successful was obtained from high resolution XPS analysis in Figure 9. Samples with RAFT moieties demonstrated a distinct component in high resolution CIs spectra due to additional C-N or C-O components compared to controls.

Example 7 - Demonstration of Low Protein Adsorption of Polyacrylamide and Poly(ethylene glycol) methyl ether methacrylate Graft Coatings on Electrospun poly(styrene-co-butyl 4-vinylbenzyl trithiocarbonate) Membranes via Europium- tagged protein adsorption assay.

Part A: Preparation of Grafted Polyacrylamide and polyPEGMA Membranes.

An electrospun poly(styrene-co-butyl 4-vinylbenzyl trithiocarbonate) membrane was prepared as per procedures outlined in parts A to D of Example 6 and cut into round discs using a 6mm diameter biopsy punch (Stiefel Laboratories). The dry mass of each sample was noted. A coating of polyacrylamide and polyPEGMA was then prepared on the samples as outlined in part E of Example 6. Instead of drying, membranes were left wet in Milli-Q water. Part B: Lanthanide Labelling of Human Serum Albumin.

Human Serum Albumin (HSA, Sigma-Aldrich) was purified with fast protein liquid chromatography (FPLC). The protein was tagged with a Eu ³⁺ chelating cage reagent at available amine sites using a commercially available europium labelling kit (Perkin Elmer

Eu-Nl ITC kit). The concentration of labelled HSA in solution was determined by total amino acid analysis. The labelling ratio of labels to molecules was established by making serial dilutions of the tagged protein, of which the number of counts were measured using time resolved fluorescence. Counts were referenced to a standard calibration curve to assess the quantity of labels present, and this was then divided by the actual number of

HSA molecules present.

Part C: Preparation of protein adsorption experiment on grafted membranes.

The moist membranes were transferred to individual wells of a 96 well "Non protein binding" plate (Corning). Solutions of Europium-labelled HSA were diluted with non europium labelled HSA at a ratio of 1 :3000. The total HSA concentration was made up to O.Olmg/mL (1.5 x 10 ^"7 M) in PBS using low protein binding centrifuge tubes (Eppendorf) and aliquot at lOOuL per well to samples with "Low protein binding" tips (Lab Advantage). Samples were covered in foil and left at room temperature overnight.

The HSA solution was carefully extracted from wells and membranes were washed with PBS 8 times with 5 minutes between each wash. The europium tag was dissociated from the chelation cage and re-complexed using the commercially available enhancement solution (Perkin Elmer). The solution was allowed to incubate for 45 minutes, then 100 μL of the solution was removed to a low auto luminescence plate (Greiner Bio-One) for counting using a time resolved fluorescence plate reader (PHERAstar) at 337 and 620 nm. Counts were compared against a standard calibration curve to quantify the amount of protein adsorbed on each of the membranes. The reported mass of adsorbed protein was scaled by substrate weight to account for differences in amount of scaffold available to graft. Replicate conditions were then averaged with outliers discarded. Results are shown in Figure 10, demonstrating that the RAFT-mediated coatings were able to reduce the amount of proteins adsorbed on the surface compared to the fibre without the graft coating.

Example 8 — Preparation of polyacrylamide, polyacrylic acid, poly(ethyleneglycomethacrylate) and polyNIPAAm. Graft coatings on an electrospun blend of polystyrene and a copolymer containing styrene and fluorinated RAFT moieties.

Part A: Synthesis of the fluorinated RAFT moiety (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10- heptadecafluorodecyl 5-vinylbenzyl trithiocarbonate).

A fluorinated RAFT moiety was synthesised in house, the chemical structure of which is shown below:

lH,l#,2H,2ff-Perfiuoro-l-decane-thiol (Aldrich, l.OOg, 0.00208mol) and carbondisulfide (Sigma- Aldrich, 0.316g, 0.25ml, 0.00416mol) were added to chloroform (Merck, 25 ml) under nitrogen at room temperature. Triethylamine (Merck, 0.63 Ig, 0.87ml, 0.00624 mol) was then added dropwise at room temperature. The reaction was stirred for 1 h at room temperature, then chloromethylstyrene (Aldrich, 90% purity, 0.002288 mol, 0.389g, 0.36 ml) in chloroform (5 ml) was added dropwise and the reaction was stirred overnight at room temperature. The reaction was washed with water (2 x 30 ml) and diluted HCl (50 ml), then dried using sodium sulphate and evaporated to dryness to give the crude product. Petroleum spirit 40-60 (Merck, 40 ml) was then added and the resulting mixture stirred. Impurities dissolved in the petroleum spirit layer were decanted out. This process of adding petroleum spirit to dissolve the impurities was repeated twice. The pure product remains at the bottom of the flask as a pale yellow powder, 700 mg, 50% yield. The product was confirmed by ¹ H NMR (CDCl ₃ , 200 MHz) 2.40-2.66 (m, 2H ₃ -CH ₂ F ₂ -), 3.56- 3.64 (m, 2H ₅ -CSSCH ₂ -), 4.61 (br.s, 2H, CH ₂ -aromatic), 5.25 (d, J=10.8 Hz, IH, CH ₂ =), 5.74 (d, J=17.6Ηz, IH, CH ₂ =), 6.62-6.76 (m, 1Η, CH=), 7.27-7.39 (m, 4Η, aromatic) ppm. ¹⁹ F nmr (CDCl ₃ , 188.29MHz) -126,68 to -126.36 (m, 2F), -123.89 to -123.55 (m, 2F), - 123.32 to -122.93(m, 2F), -122.95 to -121.90 (m, 6F), -114.82 to -114.56 (m, 2F) ₃ -81.23 (t, J=IOOHz, 3F) ppm.

Part B: Synthesis of a Copolymer Containing Styrene and the Fluorinated RAFT moiety.

Deinhibited styrene monomer (99%, 2.8 Ig, 2.7 x 10 ^'2 mol, Sigma-Aldrich) and the fluorinated RAFT moiety from Part A (2.02g, 3.0 x 10 ^"3 mol) were mixed with 6.OmL of toluene (Merck) and 23mg of azobisisobutyronitrile (AIBN). The solution was stirred and shaken to dissolve the fluorinated RAFT agent, then gently vacuum degassed for 15 minutes, then purged with dry nitrogen for 10 minutes. The degassing and purging cycle was repeated once more. The solution was then stoppered by a rubber septum, purged with nitrogen gas for a further 10 minutes and stirred for 40 hours heated at 6O ⁰ C.

The solution was diluted and placed in a dropping funnel, and the polymer precipitated by adding the solution dropwise to a large excess of methanol (Merck). The polymer was dried overnight in a vacuum oven that has been degassed and nitrogen purged twice for 20 minutes at 3O ⁰ C.

Analysis of the monomer by GPC found Mn of approximately 121, 500 and Mw 219, 000 Da.

Part C: EIectrospinning of the Blend of Polystyrene and the Copolymer Containing Styrene and Fluorinated RAFT moieties.

The copolymer containing styrene and fluorinated RAFT moieties was blended with polystyrene (MW 230,000) at a 3:2 ratio by weight and dissolved in chloroform and DMF (1:1 containing lμM DTAB). The solution was transferred to a plastic syringe fitted with a copper electrode, which was connected to a high voltage generator of a custom built electrospinning unit. The syringe was kept at a distance of 15 cm from the aluminium cathode maintained at -5 kV. Electrospinning of the solution under a voltage of 25 kV ■ produced a highly porous and fibrous membrane. The average fibre diameter determined by SEM (S570 Hitachi) was 380 ± 30 nm.

Part D: Graft Polymerisation of polyacrylamide, polyacrylic acid, poly(ethyleneglycomethacrylate) and polyNIPAAm Electrospun Polystyrene Membrane Containing RAFT Moieties.

Various monomer solutions- acrylamide (Sigma-Aldrich), 1.40 M, PEGMA (MW-475, Sigma- Aldrich), 0.22 M, Acrylic Acid (distilled, Sigma-Aldrich), 1.39 M and NIPAAm (Sigma-Aldrich), O.88M were prepared in a 50%(v/v) Milli-QTM water/ DMSO for later use. A RAFT moiety, S-benzyl, S-(2-carboxy)ethyl trithiocarbonate was also dissolved in the solution at 0.5mg/ml.

Membranes were cut into ~lcm ² pieces and wetted with a few drops of ethanol (Merck), then rinsed at least 4 times with Milli-Q™ water. Excess water was removed until the membranes were just wetted, and membranes were placed in individual wells of a 24-well plate (Nunc). The assembly was placed in a custom built stainless steel cell fitted with a glass top and taps for gas purging. The cell and monomer solutions were transferred to a nitrogen purged glove box for oxygen removal for 30 minutes, after which the monomer solutions were gently purged with nitrogen for 10 minutes. Thermal initiator 2,2'- azobis(2-amidino-propane) dihydrochloride (Wako) was added to the solution to a concentration of 0.5mg/mL, and ImL of monomer solution was dispensed to each well.

The cell was sealed to be air tight within the glovebox, then removed and placed in a vacuum oven. The reaction was left at 50°C for 72 hours with continuous nitrogen flush through the oven, after which the membranes were removed from the cell, rinsed four times with Milli-Q™ water and vacuum dried for XPS analysis.

Table 15 presents the differences in elemental composition before and after RAFT- mediated grafting. It may be observed that the ungrafted sample contained no nitrogen, and a small amount of oxygen. The RAFT mediate coating had resulted in compositional changes, where grafting of acrylamide and NIPAAm had increased nitrogen content, and grafting of PEGMA and acrylic acid resulted in increased oxygen content.

Table 15: Elemental composition determined via XPS of electrospun membranes composed of a blend of polystyrene and Blend of polystyrene and a poly(styrene-co- heptadecafluorodecyl 5-vinylbenzyl trithiocarbonate) before and after RAFT-mediated grafting with acrylamide, acrylic acid, NIPAAm and PEGMA.

Additional information can be obtained from high resolution XPS spectra of the samples. Representative high resolution CIs spectra obtained from the surface of grafted polyacrylamide and polyacrylic acid are presented in Figure 11 , and grafted polyNIPAAm and polyPEGMA are presented in Figure 12. The peak shapes have all changed with respect to the untreated scaffold and demonstrated clearly a coating had formed over the underlying membrane, and that the composition of the membrane can be controlled by use of different monomers.

Example 9 - Preparation of polyethylene glycol (PEG) graft coatings from electrospun polystyrene-vinylbenzylchloride copolymer

Part A: Synthesis of a copolymer containing styrene and 4-chloromethylstyrene moieties The copolymer was synthesized under identical conditions to that described in Example 6 Part A.

Part B: Electrospinning of polystyrene-vinylbenzylchloride copolymer membranes Aluminum foil was used as a collector for the electrospun nanofibres during electrospinning. A polystyrene-vinylbenzenchloride copolymer solution (20% w/v in chloroform: DMF =1 :1 containing lμM of DTAB) was placed in a plastic syringe at a fixed distance (15 cm) from the aluminium collector. The negative terminal was attached to the aluminium collector and maintained at -5kV. The voltage was maintained at 25kV. The flow rate was at 0.48 niL/hour. Electrospinning of the solution produced a highly porous and fibrous membrane. The average fibre diameter determined using a SEM S570 (Hitachi) was 960± 280 nm.

XPS results of the resultant fibres are presented in Table 16 and the high resolution CIs spectrum of poly(styrene-co-butyl 4-vinylbenzyl chloride) electrospun fibres shown in Figure 13.

Table 16: Elemental composition of membranes electrospun at 25kV determined by XPS

Part C: Graft Polymerisation of Polyethylene glycol methacrylate (PEGMA) from an Electrospun Membrane Containing ATRP Moieties.

PEGMA (Aldrich, Mn ~ 475) with variable solution concentration (0.05 and 0.5 M, 16 samples each) were prepared with 16 control samples (water replaced monomer in reactions). The catalyst system was composed of activating and deactivating copper compounds (Cu(I)Cl (Aj ax Fine Chemicals) and Cu(II)Cl ₂ , (Merck) respectively), a chelating ligand (Aldrich, 1,1,4,7,10,10-hexamethyltriethylenetetramine, HMTETA). No sacrificial initiator was used in these experiments. The molar proportion of monomer:CuCl:CuCl ₂ :HMTETA was 200:1 :0.15:2. The reaction was scaled to 3 mL with water as the solvent.

Before use, the monomer was stirred with a deinhibition compound and bubbled with nitrogen. Water was degassed by evacuation on a high vacuum line with nitrogen backfilling, 10 times. The catalyst system was purged in a nitrogen atmosphere before use.

Reactions took place on a gently shaking platform in a nitrogen-filled glove box for 18 hours at room temperature. Post reaction, the solutions were exposed to air to quench the reaction. The solution polymer was carefully extracted and saved for further analysis. The substrates were washed with water, 50 mM Na ₂ EDTA (BDH Anal.), and 50 mM NaHSO ₃ (Sigma-Aldrich) solutions. Finally, substrates were exhaustively washed with water and dried on aluminium foil. Dry samples were cut approximately in half for XPS analysis. Control samples were treated in a similar way to the ATRP substrates with the same handling and washing protocols except that no monomer or catalyst was added.

Element composition data in Table 17 shows the compositional change of the membrane surface before and after grafting. The grafting generally has resulted in higher oxygen content. It was also noted that using a higher concentration of PEGMA had likely created a thicker coating. High resolution XPS analysis shown in Figure 14, indicates grafting of PEGMA on the poly(styrene-co-butyl 4-vinylbenzyl chloride) as indicated by the presence of the peak at 287.5 eV due to C-O.

Table 17: Elemental composition of membranes electrospun at 25kV grafted with PEGMA at 0.05 and 0.5 M determined by XPS

Part D: Protein Adsorption Studies on PEGMA grafted polystyrene-vinylbenzylchloride membranes.

Membranes from Part C which had been washed and dried were tested for protein adsorption using the Europium labelled protein prepared in Part B of Example 7. Control samples were polystyrene-vinylbenzylchloride membranes which had undergone the same handling and washing protocols except that no monomer or catalyst was used in the grafting step. Washed and dried membranes were transferred to a "Non Protein Binding" plate (Corning), wet with a small amount of ethanol, and then fully hydrated with water. Solutions of Europium-labelled HSA were diluted with non europium labelled HSA at a ratio of 1 :3000. The total HSA concentration was made up to 0.100 mg/mL (1.5 x 10 ^"6 M) in PBS using low protein binding centrifuge tubes (Eppendorf) and aliquot at lOOuL per well to samples with "Low protein binding" tips (Lab Advantage). Binding solutions were also added to empty wells to account for protein binding to the plate alone. Samples were covered in foil and left at room temperature overnight (approximately 18 hours). The HSA solutions were carefully extracted and then the substrates were washed with PBS (5 times with 20 minutes between wash) and water (3 times, with 5 minutes between each wash). The Europium tag was dissociated with 120 uL of enhancement solution (Perkin Elmer, 35 minute incubation) and 100 μL was transferred to a low auto luminescence plate (Greiner Bio-One) for counting using a time resolved fluorescence plate reader (PHERAstar) at 337 and 620 nm. Counts were compared against a standard calibration curve to quantify the amount of protein adsorbed on each of the membranes.

The reported mass of adsorbed protein was scaled by substrate weight to account for differences in amount of scaffold available to graft. Replicate conditions were then averaged with outliers discarded.

Results of the protein adsorption study are shown in Figure 15 and demonstrate reduced protein adsorption on the PEG grafted membranes.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.