WO2014051418A1

WO2014051418A1 - Graft copolymer, method for producing such graft copolymer and composition comprising such graft copolymer

Info

Publication number: WO2014051418A1
Application number: PCT/NL2013/000046
Authority: WO
Inventors: Rob DUCHATEAU; Johan Pieter Anna Heuts; Theodorus Hoeks; Gemma Claire SANDERS
Original assignee: Stichting Dutch Polymer Institute
Priority date: 2012-09-27
Filing date: 2013-09-25
Publication date: 2014-04-03
Also published as: NL1039825C2

Abstract

The invention relates to a quaternized graft copolymer, comprising a graft copolymer having a main chain comprising N,N-dialkylamino groups, wherein the nitrogen atom of one or more of the N,N-dialkylamino groups is a quaternized nitrogen atom, wherein the quaternized nitrogen atom is part of a tri-alkyl-aryl ammonium group or a tetra-alkyl ammonium group.

Description

Graft copolymer, method for producing such graft copolymer and composition comprising such graft copolymer

The invention relates to a graft copolymer, to a quaternized graft copolymer, to a composition comprising such quaternized graft copolymer and to a method for the manufacturing of such quaternized graft copolymer.

The improvement of the properties of polymeric materials is usually focused on the bulk properties rather than on the surface properties. For example, it is now possible to prepare polycarbonate materials that have excellent bulk properties such as a high thermal stability, an excellent impact resistance and a high optical clarity, which makes polycarbonates suitable for a wide range of applications. However, polycarbonate materials are capable of building up static charge that create dirt-attracting forces. Also,

polycarbonates have the tendency to "fog" when exposed to humid

conditions, which means that the condensation of water on the surface of a polycarbonate material severely reduces the transparency of the material. This is undesirable in applications such as e.g. greenhouses, sports equipment such as diving goggles and ski masks, analytical equipment, for example microscopes, spectacle lenses, and supermarket freezer doors.

In order to improve the surface properties of polycarbonates, it is known to use so-called anti-static and anti-fogging additives, e.g. by adding them to the polycarbonate during the extrusion process or by providing them as a coating at the surface of the polycarbonate. A possible mechanism of these amphiphilic additives is accumulation and organization at the surface of the hydrophobic polycarbonate, while simultaneously the polarity of the surface is changed. The resulting surface attracts water and facilitates the dissipation of any built-up charge. Also, the surface allows a better spreading of water across the surface. A water droplet on the surface spreads out over the surface to form a continuous layer rather than discreet droplets that give the appearance of fog.

Currently, most anti-static and anti-fog additives for polycarbonate are based on small molecules comprising ammonium or phosphonium salts. However, these additives have a limited lifetime since they can easily be removed from the polymer surface. The use of polymeric anti-static and anti- fog additives has also been demonstrated. For example, Howarter er a/, have grafted fluorinated oligomers to silica surfaces using isocyanate chemistry (Adv. Mater., 2007, 19, 3838-3843 and Macromol. Rapid Commun., 2008, 29, 455-466). However, a disadvantage of these additives is that they do not withstand temperatures of 300 °C, which is a common processing

temperature for polycarbonates. When the materials are being used as an additive in polycarbonate resins, they are subject to severe degradation.

Alternatively, Tajitsu has used highly conductive butadiene rubber particles doped with Li⁺ or K⁺ dispersed in a poly(methyl methacrylate) matrix as anti-static polymer films (J. Mater. Sci. Lett. 1999, 18, 1287 and J.

Electrost. 2002, 55, 299-310). However, a disadvantage of these additives is that the rubber clusters have a negative effect on the transparency and haze. When being used, the haze will increase while transparency will decrease.

It is therefore an object of the present invention to provide an additive for polymeric substrates that provides the surface of the substrate with antistatic and/or anti-fogging properties and results in a transparent article. It is in particular an object of the present invention to provide an additive with improved anti-static and/or anti-fogging properties compared to known additives.

It is also an object of the present invention to provide an additive that has a good adhesion to the polymeric substrates and/or that has a high chemical stability, so that a more robust material and/or a material with an increased life-time is obtained. It is in particular an object of the present invention to provide an additive for polymeric substrates that gives the surface of the substrate a high impact resistance and a high scratch resistance.

It is also an object of the present invention to provide an additive that is environmentally friendly, and/or that can be produced an applied in an environmentally friendly manner.

It has now been found that this objective can be reached by using a specific polymer as an additive to a polymeric material.

Accordingly, the invention relates to a graft copolymer comprising a main chain and at least one graft linked to the main chain, wherein - the main chain comprises a polymer selected from the group of poly((/V,/V- dialkylamino)alkyl acrylate), poly((/V,A/-dialkylamino)alkyl methacrylate), poly((A/,A/-dialkylaminoalkyl)styrene) and copolymers comprising two or more different monomers selected from the group of (/V,/V-dialkylamino)alkyl acrylates, (A/,A/-dialkylamino)alkyl methacrylates and (N,N- dialkylaminoalkyl)styrene; and wherein

- the at least one graft comprises a polymer selected from the group of

poly(acrylate ester), poly(methacrylate ester), polyacrylamide,

poly(methacrylamide), polystyrene, polyalkylene, and copolymers

comprising two or more different monomers selected from the group of acrylate esters, methacrylate esters, acrylamides, methacrylamides, styrenes and alkylenes.

For the purpose of the invention, with a copolymer is meant a

polymer of two or more different monomers. Thus, a graft copolymer of the invention is made from at least two different monomers, viz. at least a first monomer that forms the main chain and a second monomer that forms the at least one graft. A graft copolymer of the invention is in particular a copolymer of at least a first monomer selected from the group of (A/,/V-dialkylamino)alkyl acrylate, (A/,A/-dialkylamino)alkyl methacrylate and {N,N- dialkylaminoalkyl)styrene and a second monomer comprising (1) a carbon- carbon double bond that is capable of participating in a polymerization

reaction with other carbon-carbon double bonds and (2) a polymer of at least one monomer selected from the group of acrylate ester, methacrylate ester, acrylamide, methacrylamide, styrene and alkylene. A third, fourth or further monomer may in principle be any suitable monomer comprising a carbon- carbon double bond that is capable of participating in a polymerization

reaction with other carbon-carbon double bonds. In particular, a third, fourth or further monomer is selected from the group of the first and second

monomer as defined hereinabove.

The poly((N,/V-dialkylamino)alkyl acrylate), if present in the main chain, may in principle be any poly((/V,/V-dialkylamino)alkyl acrylate). This means that it may be a polymer of any (A/,/V-dialkylamino)alkyl acrylate.

Analogously, the poly((A/,A/-dialkylamino)alkyl methacrylate), if present in the main chain, may in principle be any poly((/\/,/V-dialkylamino)alkyl

methacrylate). This means that it may be a polymer of any (N,N- dialkylamino)alkyl methacrylate.

The poly((A/,A/-dialkylamino)alkyl acrylate) may also be a polymer of two or more different (N,/V-dialkylamino)alkyl acrylate monomers, i.e. a copolymer. The two or more different (A/,/V-dialkylamino)alkyl acrylate monomers may be present in the copolymer in a regular fashion or in a random fashion.

The poly((/V,A/-dialkylamino)alkyl methacrylate) may also be a polymer of two or more different (A/,A/-dialkylamino)alkyl methacrylate monomers, i.e. a copolymer. The two or more different

(/V,/V-dialkylamino)alkyl methacrylate monomers may be present in the copolymer in a regular fashion or in a random fashion.

The alkyi ester group of the poly((/V,/V-dialkylamino)alkyl acrylate) and/or poly((/V,A/-dialkylamino)alkyl methacrylate) and the respective monomers thereof (i.e. (/V,/V-dialkylamino)alkyl acrylate and (N,N- dialkylamino)alkyl methacrylate)) usually comprise 2-10 carbon atoms.

Preferably it is selected from the group of ethyl, propyl, butyl and pentyl. In particular it is an alkyi group wherein the carbon that is connected to the oxygen of the ester moiety is a primary carbon atom, such as e.g. ethyl,

1 -propyl, 1 -butyl and 1 -pentyl. More in particular, the alkyi group is a linear alkyi group.

The two alkyi groups of the Λ/,/V-dialkylamino moiety of the (N,N- dialkylamino)alkyl acrylate and/or (N,/V-dialkylamino)alkyl methacrylate) are usually independently chosen from the group of methyl, ethyl and propyl. More preferably the alkyi groups are both methyl groups.

The connection of the nitrogen atom of the A/,A/-dialkylamino moiety to the alkyi group of the alkyi acrylate ester usually occurs at a primary carbon atom of that alkyi group, e.g. the terminal carbon in case that alkyi group is a linear alkyi group.

In case a poly((/v /V-dialkylamino)alkyl acrylate) is present, it is preferably a polymer of a monomer selected from the group of

A/,/V-dialkylamino)ethyl acrylate, (A/,/V-dialkylamino)propyl acrylate and (/V,/V-dialkylamino)butyl acrylate (i.e. it is a polymer selected from the group of poly((N,/V-dialkylamino)ethyl acrylate), poly((/V,/V-dialkylamino)propyl acrylate) and poly((A/,A/-dialkylamino)butyl acrylate)).

More preferably it is a polymer of a monomer selected from the group of 2-(/V,A/-dimethylamino)ethyl acrylate, 3-(A/,/V-dimethylamino)n-propyl acrylate and 4-(N,/V-dimethylamino)n-butyl acrylate (i.e. it is a polymer selected from the group of poly(2-(A/,N-dimethylamino)ethyl acrylate), poly(3- (A/,A/-dimethylamino)n-propyl acrylate) and poly(4-(A/,A/-dimethylamino)A7-butyl acrylate).

In case a copolymer of two or more different (A/,A/-dialkylamino)alkyl acrylate monomers is present, the monomers are preferably selected from the group of (A/,A/-dialkylamino)ethyl acrylate, (A/,/V-dialkylamino)propyl acrylate and (A/,/V-dialkylamino)butyl acrylate. More preferably, the monomers are selected from the group of 2-(N,N-dimethylamino)ethyl acrylate,

3-(N,N-dimethylamino)n-propyl acrylate, 4-(A/,N-dimethylamino)/7-butyl acrylate.

In case a poly((A/,A/-dialkylamino)alkyl methacrylate) is present, it is preferably a polymer of a monomer selected from the group of

A/,/\/-dialkylamino)ethyl methacrylate, (/V,/V-dialkylamino)propyl methacrylate and (A/,A/-dialkylamino)butyl methacrylate (i.e. it is a polymer selected from the group of poly((N,/V-dialkylamino)ethyl methacrylate),

poly((N,/V-dialkylamino)propyl methacrylate) and poly((/V,/V-dialkylamino)butyl methacrylate)).

More preferably it is a polymer of a monomer selected from the group of 2-(N,A/-dimethylamino)ethyl methacrylate, 3-(/V,A/-dimethylamino)n-propyl methacrylate and 4-(/V,/V-dimethylamino)n-butyl methacrylate (i.e. it is a polymer selected from the group of poly(2-(/V,A/-dimethylamino)ethyl methacrylate), poly(3-(A/,A/-dimethylamino)n-propyl methacrylate) and poly(4- (A/,N-dimethylamino)n-butyl methacrylate).

In case a copolymer of two or more different (A/,A/-dialkylamino)alkyl methacrylate monomers is present, the monomers are preferably selected from the group of (A/,A/-dialkylamino)ethyl methacrylate,

(/ /,/\/-dialkylamino)propyl methacrylate and (A/,/V-dialkylamino)butyl methacrylate. More preferably, the monomers are selected from the group of 2-(/V,A/-dimethylamino)ethyl methacrylate, 3-(A/,N-dimethylamino)n-propyl methacrylate, 4-(N,N-dimethylamino)n-butyl methacrylate.

The poly((A/,N-dialkylaminoalkyl)styrene), if present in the main chain, may in principle be any poly((/V,/V-dialkylaminoalkyl)styrene). This means that it may be a polymer of any (/V,/V-dialkylaminoalkyl)styrene. In particular, the monomer is 4-(A/,A/-dialkylaminoalkyl)styrene), i.e. styrene wherein the aromatic ring is substituted with a Λ/,/V-dialkylaminoalkyl group at the 4-position.

The poly((/V,A/-dialkylaminoalkyl)styrene) may also be a polymer of two or more different (/V,/V-dialkylaminoalkyl)styrene monomers, i.e. a copolymer. The two or more different (A/,A/-dialkylaminoalkyl)styrene monomers may be present in the copolymer in a regular fashion or in a random fashion.

The alkyl group connecting the (A/,A/-dialkylamino) group with the aromatic ring of the styrene usually comprises 2-10 carbon atoms. Preferably it is selected from the group of ethyl, propyl, butyl and pentyl. In particular it is an alkyl group wherein the carbon that is connected to the aromatic ring is a primary carbon atom, such as e.g. ethyl, 1 -propyl, 1 -butyl and 1 -pentyl. More in particular, the alkyl group is a linear alkyl group.

The two alkyl groups of the (A/./V-dialkylamino) group are usually independently chosen from the group of methyl, ethyl and propyl. More preferably the alkyl groups are both methyl groups.

The connection of the nitrogen atom of the (A/./V-dialkylamino) group to the alkyl group on the aromatic ring usually occurs at a primary carbon atom of that alkyl group, e.g. the terminal carbon in case that alkyl group is a linear alkyl group.

In case a poly((A/,/V-dialkylaminoalkyl)styrene) is present, it is preferably a polymer of a monomer selected from the group of (N,N- dialkylaminoethyl)styrene, (A/,/V-dialkylaminopropyl)styrene and (N,N- dialkylaminobutyl)styrene (i.e. it is a polymer selected from the group of poly((/V,A/-dialkylaminoethyl)styrene), poly((/V,A/-dialkylaminopropyl)styrene) and poly((A/,/V-dialkylaminobutyl)styrene). More preferably it is a polymer of a monomer selected from the group of (2-(A/,A/-dimethylamino)ethyl)styrene, (3-(N,N- dimethylamino)/7-propyl)styrene and (4-(A/,/V-dimethylamino)n-butyl)styrene (i.e. it is a polymer selected from the group of poly((2-(A/,/V- dimethylamino)ethyl)styrene), poly((3-(/V,A/-dimethylamino)n-propyl)styrene) and poly((4-(/V,/V-dimethylamino)n-butyl)styrene).

Even more preferably it is a polymer of a styrene monomer having an A/./V-dialkylaminoalkyl group at the 4-position of the aromatic ring, such as a styrene monomer selected from the group of 4-(2-(Λ/,Λ/- dimethylamino)ethyl)styrene, 4-(3-(/V,/V-dimethylamino)n-propyl)styrene and 4-(4-(/V,/S/-dimethylamino)n-butyl)styrene (i.e. it is a polymer selected from the group of poly(4-(2-(A/,A/-dimethylamino)ethyl)styrene), poly(4-(3-(/V,/V- dimethylamino)n-propyl)styrene) and poly(4-(4-(A/,/V-dimethylamino)n- butyl)styrene).

In case a copolymer of two or more different

(N,/V-dialkylaminoalkyl)styrene monomers is present, the monomers are preferably selected from the group of (A/,A/-dialkylaminoethyl)styrene, (N,N- dialkylaminopropyl)styrene and (A/,/V-dialkylaminobutyl)styrene. More preferably, the monomers are selected from the group of 4-(2-(/V,/V- dimethylamino)ethyl)styrene, 4-(3-(A/,/V-dimethylamino)n-propyl)styrene and 4-(4-(A/,N-dimethylamino)n-butyl)styrene.

The polymer in the main chain may be a copolymer comprising two or more different monomers selected from the group of (N,N- dialkylamino)alkyl acrylates, (A/,/V-dialkylamino)alkyl methacrylates and (N,N- dialkylaminoalkyl)styrenes. This means, for example and as exemplified hereinabove, that the polymer is a copolymer of two different (N,N- dialkylamino)alkyl acrylates or that it is a copolymer of two different (N,N- dialkylamino)alkyl methacrylates. It may however also mean that the polymer is a copolymer of an (A/,A/-dialkylamino)alkyl acrylate and an (N,N- dialkylamino)alkyl methacrylate, or that it is a copolymer of an (N,N- dialkylamino)alkyl acrylate and an (N,/V-dialkylaminoalkyl)styrene, or that it is a copolymer of an (A/,/V-dialkylamino)alkyl methacrylate and an (N,N- dialkylaminoalkyl)styrene. A graft of a graft copolymer of the invention comprises a polymer selected from the group as defined in claim . Such graft may therefore also comprise other moieties than those defined in claim 1. However, a graft may also consist of a polymer selected from the group as defined in claim 1. This means that no other moieties than those defined in claim 1 are present in the graft.

A graft may be linked to the main chain by for example a carbon- carbon linkage, an ether linkage or an ester linkage.

In case a graft comprises poly(acrylate ester), it may in principle be any poly(acrylate ester). In case the ester is an alkyl ester, the alkyl group of the poly(alkyl acrylate) usually comprises 1-20 or 1 -10 carbon atoms. It may be a cyclic alkyl group having a ring of 4-8 carbon atoms such as cyclopentyl, cyclohexyl or methylcyclohexyl. It may also be an acyclic alkyl group such as methyl, ethyl, propyl, butyl, pentyl or hexyl. As an acyclic alkyl group, in particular lauryl and stearyl may be used. In case the ester is an aryl ester, the aryl group of the poly(aryl acrylate) usually comprises 3-20 or 3-10 carbon atoms. The aryl group may comprise a phenyl group (with or without substituents on the ring) or a naphtyl group (with or without substituents on one or both rings).

The poly(acrylate ester) may also be a polymer of two or more different acrylate estermonomers, i.e. a copolymer. The two or more different acrylate estermonomers may be present in the copolymer in a regular fashion or in a random fashion.

In case a graft comprises poly(methacrylate ester), it may in principle be any poly(methacrylate ester). In case the ester is an alkyl ester, the alkyl group of the poly(alkyl methacrylate) usually comprises 1-20 or 1 -10 carbon atoms. It may be a cyclic alkyl group having a ring of 4-8 carbon atoms such as cyclopentyl, cyclohexyl or methylcyclohexyl. It may also be an acyclic alkyl group such as methyl, ethyl, propyl, butyl, pentyl or hexyl. As an acyclic alkyl group, in particular lauryl and stearyl may be used. In case the ester is an aryl ester, the aryl group of the poly(aryl acrylate) usually comprises 3-20 or 3-10 carbon atoms. The aryl group may comprise a phenyl group (with or without substituents on the ring) or a naphtyl group (with or without substituents on one or both rings).

The poly(methacrylate ester) may also be a polymer of two or more different methacrylate estermonomers, i.e. a copolymer. The two or more different methacrylate estermonomers may be present in the copolymer in a regular fashion or in a random fashion. For example, the polymer may be a copolymer of cyclohexyl methacrylate comonomer and methyl methacrylate comonomer.

The use of a graft copolymer of the invention as an anti-static and/or an anti-fog additive into a polymer requires - among others - a good compatibility of the additive with the polymer. This in particular means that the grafts of a graft copolymer of the invention reveal a useful degree of miscibility with the polymer. Experiments showed that a useful degree of miscibility with a polycarbonate, in particular with an aromatic polycarbonate based on bisphenol A (which is commercially available under the trade name Lexan GLX 43), can be obtained when the poly(methacrylate ester) in a graft is a copolymer of cyclohexyl methacrylate comonomer and methyl

methacrylate comonomer. The ratio wherein these monomers are present in the graft may be in the range of 10 : 90 to 90 : 10. Preferably, the ratio of cyclohexyl methacrylate : methyl methacrylate is in the range of 20 : 80 to 50 : 50. More preferably it is 25 : 75.

In case a graft comprises polystyrene, the polystyrene may be a polymer of normal styrene monomer or a substituted styrene monomer. In case styrene is one of the different monomers in a copolymer, the styrene may also be normal styrene monomer or a substituted styrene monomer. In case a graft comprises a copolymer wherein styrene (or a substituted styrene) is one of the two different monomers, the other monomer may in particular be maleic anhydride. An advantage of these monomers is that these monomers are almost perfectly alternating, making it an essentially alternating copolymer of a well-defined structure. Also, the maleic groups are reactive towards amines.

In case a graft comprises polyalkylene, it may in principle be any polyalkylene. The alkylene monomer usually comprises 2-10 carbon atoms, preferably 2-6 carbon atoms. The polyalkylene is usually a poly(alpha-olefin). The polyalkylene may for example be polyethylene, polypropylene or polybutylene. It may also be a copolymer such as poly(ethylene-co-hexene).

A graft of a graft copolymer of the invention may also comprise a polymer that is formed from two or more different types of monomers, such that the polymer comprises two or more different monomers selected from the group of acrylate ester, methacrylate ester, acrylamide, methacrylamide, styrene and alkylene.

In case a graft comprises a polymer of an acrylamide or a

methacrylamide, it may in principle be any acrylamide or any methacrylamide. Usually, the unsubstituted acrylamide or unsubstituted methacrylamide is used, but /V-alkylated acrylamide or /V-alkylated methacrylamide may also be used. A particular /V-alkylated acrylamide is (/V-/^'so-propyl)acrylamide, and a particular /V-alkylated methacrylamide is (/V-/so-propyl)methacrylamide.

The molar mass of a graft of a graft copolymer of the invention (and also the number average molar mass Mn of all grafts of graft copolymer of the invention) is usually in the range of 750-20,000 g/mol, preferably it is in the range of 1 ,000-10,000 g/mol, more preferably it is in the range of 1 ,500- 6,000 g/mol. For a graft comprising poly(acrylate ester), the molar mass of the graft (and also the number average molar mass Mn of all grafts) is in the range of 1 ,000-10,000 g/mol, preferably in the range of 1 ,500-3,000 g/mol.

A graft copolymer of the invention comprises one or more grafts. This means that the main chain of each polymer molecule has at least one graft attached to it. Usually, the average number of grafts per main chain is in the range of 1-25, preferably in the range of 1 -10, more preferably in the range of 1-3.

The grafts on a chain are not necessarily the same. They may differ in terms of degree of polymerization, in terms of the type of monomer that is present, and - in case more than one type of monomer is present in the grafts - in terms of the types of monomers that are present and/or in terms of their relative abundances in the polymeric graft. A graft copolymer of the invention usually has a number average molar mass (M_n) in the range of 4,000 to 40,000 g/mol, preferably in the range of 8,000 to 20,000 g/mol.

The invention further relates to a quaternized graft copolymer, comprising a graft copolymer of the invention wherein the nitrogen atom of one or more of the A/./V-dialkylamino groups is a quaternized nitrogen atom, wherein the quaternized nitrogen atom is part of a tri-alkyl-aryl ammonium group or of a tetra-alkyl ammonium group. Herein, it is understood that one of the alkyl groups of the tri-alkyl-aryl and tetra-alkyl moieties is the alkyl group that connects the nitrogen atom of the ammonium group to its monomer residue in the main chain, such as an alkyl acrylate ester residue, an alkyl methacrylate ester residue or a styrene residue.

The quaternization is usually carried out with a halide compound, such as an aliphatic halide or an aromatic halide. An aliphatic halide may for example comprise an alkyl or a cycloalkyl group. An alkyl group may have 1- 8 carbon atoms (e.g. methyl, ethyl, propyl, butyl, pentyl, hexyl,

perfluorohexyl), and a cycloalkyl group may have 4-10 carbon atoms (e.g. cyclopentyl, cyclohexyl, methylcyclohexyl). An aromatic halide usually comprises an aryl of 3-20 or 3-10 carbon atoms. The aryl group may comprise a phenyl group (with or without substituents on the ring) or a naphtyl group (with or without substituents on one or both rings).

The halide is in particular selected from the group of chloride, bromide and iodide, preferably the halide is iodide. Preferably, the halide compound is methyl iodide or perfluorohexyl iodide. This means that a quaternized nitrogen atom in a quaternized graft copolymer is preferably part of a methyl-trialkyl-ammonium iodide group or a perfluorohexyl-trialkyl- ammonium iodide group.

It is not necessary that the nitrogen atom of all A/,A/-dialkylamino groups is a quaternized nitrogen atom. Accordingly, a polymer of the invention may have a certain degree of quaternization. The degree of quaternization is defined as the percentage of quaternizable nitrogen atoms in the graft copolymer that is actually quaternized. The degree of quaternization is usually in the range of 20-100%. Preferably the degree of quaternization is in the range of 50-100%, more preferably it is in the range of 80-100%. A high degree of quaternization is advantageous not only for reaching effective anti- fogging and/or anti-static properties, but also for reaching a stable material. Some polymers, in particular polycarbonates, are sensitive to degradation due to the presence of free amines in the polymers (i.e. amines that are not quaternized).

The invention further relates to a composition comprising a polymer and a quaternized graft copolymer as described hereinabove.

The polymer may in principle be any polymer that may suffer from the built-up of static charge and/or from fogging. Preferably, the polymer is selected from the group of polycarbonates such as poly(bisphenol A carbonate); polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT); polyvinyl alcohol (PVA); polyvinyl chloride (PVC); polyolefins such as polyethylene (PE), high-performance polyethylene (HPPE) and polypropylene (PP). Preferably, the polymer is a polycarbonate.

The composition may be a mixture of the polymer and the

quaternized graft copolymer. This means that the composition is a single substance that is a mixture of both compounds. In such mixture, both compounds are preferably mixed at the molecular level. More preferably, both compounds are dissolved in each other. The mixture may be a homogeneous mixture, and may also contain a gradient of the quaternized graft copolymer towards the surface of the polymer, wherein the concentration of the graft copolymer increased towards the surface. Such mixture can be obtained by extruding a mixture of the polymeric substrate and a copolymer of the invention.

In the case of a mixture, the amount of quaternized graft copolymer present in and/or on the polymer depends on the thickness of the polymeric substrate, in particular on the surface to volume ratio. The amount of quaternized graft copolymer that needs to be present in and/or on the polymer for obtaining one or more advantageous effects of the invention can be determined by the skilled person via routine experimentation.

The composition may also be a layered structure, wherein a layer of the quaternized graft copolymer is present on a surface of the polymer. Such layer can be applied by conventional methods, e.g. by using a bar applicator, by using a coil applicator or by spraying the material on the surface.

In the case of a layered structure, the layer of quaternized graft copolymer is usually in the range of 10-40,000 nm, preferably in the range of 50-10,000 nm, more preferably in the range of 100 to 3,000 nm.

It is contemplated that the grafts of a quaternized graft copolymer of the invention interact with the polymeric substrate so as to provide a good adhesion, while the main chain provides the actual anti-static and/or anti- fogging functionality. Accordingly, and as already mentioned hereinabove, it is necessary that there is a good compatibility of the additive with the polymer, in particular with the grafts. This means that the grafts interact or even mix with the polymeric substrate so as to achieve the desired adhesion, while the main chains remain at the surface of the substrate providing it with the antistatic and/or anti-fogging properties. Achieving such an arrangement of a copolymer of the invention at the surface of a substrate preferably occurs in a self-structuring manner, for example when the copolymer is added during extrusion of the polymeric substrate and then migrates to the surface. A more passive arrangement of a copolymer of the invention can also occur, for example when the copolymer is provided as layer that adheres to the surface of the substrate.

Given the properties of a certain polymeric substrate, a copolymer of the invention can thus in principle be designed to be compatible with that polymeric substrate, e.g. by tuning the polarity of the grafts by substituting some or all of the monomers from which the grafts are prepared for other monomers, by changing the Mn of the grafts or by changing the number of grafts per main chain.

The invention further relates to a method for preparing a graft copolymer of the invention, comprising

- preparing a macromonomer comprising (1 ) a carbon-carbon

double bond that is capable of participating in a polymerization reaction with other carbon-carbon double bonds and (2) a polymer of at least one monomer selected from the group of alkyl acrylate, alkyl methacrylate, acrylamide, methacrylamide, styrene and alkylene; then

- copolymerizing the macromonomer with a monomer selected from the group of (Λ/,/V-dialkylamino) acrylate ester, {N,N- dialkylamino) methacrylate ester and (N,N- dialkylaminoalkyl)styrene to form a graft copolymer.

Macromonomers may prepared by catalytic chain transfer

polymerization (CCTP). CCTP is a radical polymerisation process, wherein the chain length can be controlled by allowing catalytic chain transfer of growing chains to take place, and wherein the produced polymer contains a polymerisable end-group. This is usually achieved by adding a catalytic chain transfer agent to the reaction mixture of the monomer and the radical initiator. For the preparation of methacrylic macromonomers, it is preferred to use CCTP. Also macromonomers comprising an alternating copolymer of maleic anhydride and styrene may be prepared by CCTP. When the macromonomer is prepared by CCTP, it is preferred to perform its copolymerization with a monomer selected from the group of (A/./V-dialkylamino) acrylate ester and (A/,A/-dialkylaminoalkyl)styrene.

Macromonomers may also be prepared by high-temperature acrylate polymerization, which is also a radical polymerisation process. For the preparation of acrylic macromonomers, it is preferred to use the high- temperature acrylate polymerization.

Macromonomers may also be prepared by connecting (1 ) an ethylenic compound selected from the group of acrylic acid or an ester forming derivative thereof, methacrylic ester or an ester forming derivative thereof and a styrene derivative having a halide substituent on the aromatic ring, with (2) a polymer of at least one monomer selected from the group of acrylate ester, methacrylate ester, acrylamide, methacrylamide, styrene and alkylene, which polymer is functionalized with an hydroxy end-group.

For example, a methacrylic macromonomer with a reactive

methacrylic end-group may be prepared by reacting methacryloyl chloride with the OH-group of a methacrylic polymer functionalized with an OH end-group. In this way, an ester of methacrylic acid is obtained. Analgously, a methacrylic macromonomer with a reactive styrene end-group may be prepared by reacting a styrene monomer having an alkyl halide substituent on the phenyl ring (e.g. para-chloromethylstyrene) with the OH-group of a methacrylic polymer functionalized with an OH end-group. In this way, the polymeric part is connected to the styrene moiety via an ether bond .

The invention further relates to a graft copolymer obtainable by a method of the invention.

The invention further relates to a method for preparing a quaternized graft copolymer, comprising quaternizing the nitrogen atom of one or more of the /V,/V-dialkylamino groups of a graft copolymer of the invention.

The invention further relates to a quaternized graft copolymer obtainable by this method.

The quaternizing is usually performed with a halide compound such as an aliphatic halide or an aromatic halide, as described hereinabove.

However, the preparation of a quaternized graft polymer of the invention does not necessarily have to be performed by the quaternization of nitrogen atoms of an intermediate graft polymer. Thus, the graft polymer as claimed in claim 1 is only one of the possible intermediate prodcuts from which a quaternized graft polymer of the invention can be prepared.

Another method to obtain a quaternized graft copolymer comprises functionalizing a residue in the backbone of an intermediate graft polymer with a tetra-alkyl-ammonium group or a tri-alkyl-aryl-ammonium group. In this method, the nitrogen atom of the ammonium group is not present in the intermediate, but it is introduced in the final stage.

In the copolymerization reaction to form the intermediate graft copolymer, this requires the use of a monomer that is capable of being functionalized with such ammonium group when it is present as a residue in the main chain. Such monomer may for example be a styrene-based monomer, containing on the phenyl ring a haloalkylsubstituent that is capable of being substituted by a trialkylamine or a dialkyl-arylamine to form a tetra- alkyl-ammonium group or a tri-alkyl-aryl-ammonium group, respectively, on the phenyl ring. In particular, such monomer is 4-chloromethyl styrene. Thus, when this monomer is one of the comonomers applied in the copolymerization with the macromonomer, the resulting main chain of the graft copolymer

comprises 4-chloromethyl styrene groups. Subsequent reaction of the copolymer with a trialkylamine or a dialkyl-arylamine results in a quaternized copolymer having a methyl-trialkyl-ammonium chloride group or a methyl- dialkyl-aryl-ammonium chloride group. In the event that (N,N- dialkylamino)alkyl acrylate and/or (A/,/V-dialkylamino)alkyl methacrylate monomers are also present during the copolymerization, their quaternisation may be performed according to the method of the invention, e.g. by the reaction with an alkyl or aryl halide.

Thus, the invention also relates to a graft copolymer comprising a main chain and at least one graft linked to the main chain, wherein

- the main chain comprises a polymer of styrene monomer having an

haloalkyl substituent on the phenyl ring or a copolymer of a styrene monomer having an haloalkyl sustituent on the phenyl ring and one or more different monomers selected from the group of (/V,/V-dialkylamino)alkyl acrylates and (A/,/V-dialkylamino)alkyl methacrylates; and wherein

- the at least one graft comprises a polymer selected from the group of

poly(acrylate ester), poly(methacrylate ester), polyacrylamide,

poly(methacrylamide), polystyrene, polyalkylene, and copolymers comprising two or more different monomers selected from the group of acrylate ester, methacrylate ester, acrylamides, methacrylamides, styrenes and alkylenes.

The haloalkyl substituent usually comprises 1-10, preferably 1-4 carbon atoms. The alkyl group of the haloalkyl substituent is usually a linear alky having the halogen at the terminal carbon atom. The haloalkyl

substituent usually comprises one halogen. In case it contains one halogen, it is usually bromine or chlorine.

Thus, the invention also relates to a method for preparing a graft copolymer of the invention, comprising

- preparing a macromonomer comprising (1 ) a carbon-carbon

- copolymerizing the macromonomer with a styrene monomer having an haloalkyi substituent on the phenyl ring to form a graft copolymer.

The invention further relates to a graft copolymer obtainable by this method.

The invention further relates to a method for preparing a quaternized graft copolymer, comprising reacting the haloalkyi substituent on the phenyl ring of the styrene residues in a graft copolymer of the invention with a trialkylamine.

EXAMPLES

Materials and methods General considerations. All syntheses and manipulations of air- and moisture-sensitive materials were carried out in oven-dried Schlenk-type glassware on a dual manifold Schlenk line.

Materials. Methyl metharylate (MMA, 99%, Sigma-Aldrich), cyclohexyl methacryate (CHMA, 97%, Alfa Aesar) and 2-(N,N- dimethylamino)ethyl acrylate (DMAEA, 98%, Alfa Aesar) were passed over a column of activated basic alumina to remove the inhibitor.

Azobis(isobutryonitrile) (AIBN) was purchased from Sigma-Aldrich and recrystallized twice from methanol. The bis(methanol) complex of

bis[(difluoroboryl)-dimethylglyoximate]cobalt II (COBF), was prepared as described in Inorg. Chem., 1986, 25, 4108-4 14 and in Macromolecules, 1996, 29, 8083-8091. The chain transfer activity of the complex was determined in methyl methacrylate (MMA) bulk polymerisation at 60 °C and found to be equal to 30 χ 10³. For all experiments, a single batch of catalyst was used. Toluene, pentane, tetrahydrofuran (THF), Hexafluoroisopropanol (HFIP) and ethanol (AR, Biosolve) were used as received. Lexan GLX143 polycarbonate (PC) was provided by Sabic IP.

Synthesis of p(CHMA-co-MMA) via CCTP. COBF (1.0 mg, 2.5 μιτιοΙ) and AIBN (42 mg, 254 pmol) were weighed into a round bottom flask equipped with a magnetic stirrer bar. The flask was then evacuated and refilled 3 times. Argon was bubbled through toluene and a stock solution of cyclohexyl methacrylate (CHMA, 25 mol%) and methyl methacrylate (MMA, 75 mol%) for 30 minutes prior to use. Toluene (50 mL) and MMA/CHMA stock solution (50 mL) were added to the flask. The reaction was carried out at 60 °C for 18 hours with continuous stirring, after which it was quenched by cooling in ice and the addition of hydroquinone. The residual solvent and MMA was removed via rotary evaporation. The polymer was then redissolved in toluene and precipitated in pentane to remove residual catalyst and monomer and dried under vacuum for 24 hours.

Synthesis of p(DMAEA-g-(CHMA-co-MMA)) via free radical polymerisation. Macromonomer (35g, 16 mmol), AIBN (0.5 wt % based on DMAEA and macromonomer), DMAEA (23 g, 0.16 mol) and 100 g toluene were placed in a vial. N2 was bubbled through for 30 minutes and then the reaction mixture heated to 60 °C and stirred for 72 hours. Additional shots of AIBN (0.5 wt %) were added after each 24 hours. Quenching of the reaction was achieved by cooling in ice followed by the addition of hydroquinone. The polymer mixture was then precipitated into pentane, re-dissolved in THF and then re-precipitated into pentane and dried overnight in a vacuum oven.

Quaternization of polymers with methyl iodide. p(DMAEA-g- (CHMA-co-MMA)) (20 g, 67 wt% DMAEA) was dissolved in 3 L THF. Methyl iodide (Mel, 11 mL, 0.18mol) was then added and the reaction mixture stirred at room temperature. After a few minutes the polymer began to precipitate out of solution however the reaction was left to stir overnight in order to reach completion. Residual Mel and THF were evaporated from the precipitated polymer. The polymer was then dried in a vacuum oven at 40 °C overnight.

Quaternization of polymers with perfluorohexyl iodide.

p(DMAEA-g-(CHMA-co-MMA)) (6.4 g, 67% DMAEA) was dissolved in 150 mL DMF and heated to 85 °C. Perfluorohexyl iodide (FHI, 6.5 mL, 30 mmol) was then added and the reaction mixture stirred at 85 °C for 7 days. The polymer was then dialyzed (1 ,000 Da) against water to remove residual FHI and DMF. The polymer was then isolated by removing the water using a freeze-drier.

Application of quaternized polymer coatings. The quaternized polymers were dissolved in water/ethanol mixtures and applied to a

polycarbonate substrate using a coil applicator. Coating thicknesses were varied by using different applicators and different solution concentrations. Once applied, the coatings were left to dry then placed in a vacuum oven at 20 °C overnight.

Measurements. Size exclusion chromatography (SEC) was measured on a system equipped with a Waters 1515 Isocratic HPLC pump, a Waters 2414 refractive index detector (40 °C), a Waters 2707 autosampler and a PSS PFG guard column followed by 2 PFG-linear-XL (7 pm, 8 * 300 mm) columns in series at 40 °C. HFIP with potassium trifluoroacetate (3 g/L) was used as eluent at a flow rate of 0.8 mL/min. The molecular weights were calculated against poly(methyl methacrylate) standards (Polymer

Laboratories, Mp = 580 Da up to Mp = 7.1 10⁶ Da). Data acquisition and processing were performed using WATERS Empower 2 software. ¹H, ¹³C and gHMQC NMR spectra were recorded on a Varian Mercury Vx (400 MHz) spectrometer at 400 MHz. D2O, DMSO-cfe or chloroform-cfe and

tetramethylsilane were used as solvents and internal standard, respectively. Surface resistivity measurements were carried out on a Keithley 8009

Resistivity Test Fixture and measured using a 6517A electrometer/high resistance meter. The measuring time was 600 seconds with an alternative voltage of 500 V. The measurements were carried out according to the 6517 HiR Test. Static decay measurements were carried out on a Static

Honestmeter Type S-5109 (Shishido Electrostatic Ltd.) using a voltage of 10 kV. Measurements carried out at 23°C and 50% relative humidity. Static contact angles were measured using a Kruss Drop Shape Analysis System DSA 10 MK2 instrument at room temperature. 1 pL deionized water was used and contact angles recorded for up to 160 seconds. Dynamic advancing and receding contact angles were recorded using a Dataphysics OCA30 instrument at room temperature. A drop of deionized water was swollen with a further 2 pL at 0.1 pL/s and then retracting the same amount at the same speed. There was a 1s delay period between injection and retraction. All data are the average of at least 3 measurements. Results

Synthesis of p(CHMA-co-MMA). Macromonomers of cyclohexyl methacrylate (CHMA) and methyl methacrylate (MMA) containing 25 wt% of CHMA were synthesized via catalytic chain transfer polymerization (Table 1) using ppm amounts of COBF as the chain transfer catalyst and AIBN as the radical source. Macromonomers of two different lengths were synthesized (MMi and MM2) and found to have a CHMA content of 17-20 wt%,

determined via H NMR.

Table 1. Properties of p(CHMA-co-MMA) copolymers made via CCTP.

„^a/g

Entry COBF/ppm Conversion PDF DPn^b FMMA^b mol ¹

MMi 6.1 0.53 1,580 1.4 20 83 MM₂ 2.6 0.67 2,900 1.7 41 80

Determined using SEC based on polystyrene standards in THF; ^b

Determined using Ή NMR based on the integral of the vinylic protons (6.2 and 5.5 ppm), CH (CHMA, 4.7 ppm) and OCH₃ (MMA, 3.6 ppm).

Synthesis of p(DMAEA-g-(CHMA-co-MMA)) The CHMA-MMA macromonomers were then copolymerized with 2-(/V,/V-dimethylamino)ethyl acrylate (DMAEA) in the presence of AIBN as the radical initiator. The consumption of the vinylic bonds of both the monomer and macromonomer was followed using ¹H NMR, and additional initiator was added until full conversion of both the monomer and macromonomer had been reached. The resultant four graft copolymers have been analyzed using ¹H NMR and SEC. The four graft copolymers are the combinations of two different starting macromonomers (MMi and MM2) and two different grafting densities for each macromonomer (Table 2). The ratio of macromonomer to monomer (DMAEA) was shown to be similar when determined experimentally from NMR and when calculated based on monomer feed and DMAEA conversion. Table 2. Properties of p(DMAEA-g-(CHMA-co-MMA)). G and Gib are synthesised using MMi, and G_2a and G₂b from MM₂.

Entry Target ratio of Ratio Z/gmol^"1 PDF Grafts per

MM:M^a MM:M^a'^b chain^d

G_la l^a:35 1 :33 19,200 1.8 3

Gib :10 1 : 10 8,900 1.6 2.5

G₂ l^b:35 1 :32 13,200 1.5 1.5

G₂b l^b:15 1 :16 10,700 1.4 1.5 a Molar ratio; ^b Determined using ^lH NMR based on the ratio of integrals of CH (CHMA, 4.7 ppm), OCH₃ (MMA, 3.6 ppm) and CH₂N (DMAEA, 4.1 pm); ^c Determined via SEC, measured against poly(methyl methacrylate) standards in HFIP; ^d Approximate, calculated based on: grafts per chain = Mn, graft copolymer

(SEC)/Mn, macromonomer (NMR) + (DMAEA units per MM ^χ molar mass of DMAEA).

Quaternization of the polymers. The amine groups of the graft copolymers were quaternized using two different quaternizing agents: methyl iodide (Me!) and perfluorohexyl iodide (FHI). As can be seen in Table 3, a range of graft copolymers of CHMA, MMA and DMAEA have been

quaternized to varying degrees using Mel or FHI. These polymers were subsequently tested for their anti-static and anti-fogging properties.

Table 3. Overview of synthesized polymers

Macro- Graft Quaternized „ monom Copoly Graft Description⁸ ydro hⁱhc

. monomer er mer Copolymer p[(DMAEA₃₃-g-(MMAi₈- 0.68 MMi Gia Gia-m97 co-CHMA2))]₃ quaternized

with Mel (97%)

p[(DMAEA₃₃-g-(MMAi₈- ^{0 9} Gia-m6o co-CHMA₂))]₃ quaternized

with Mel (60%)

p[(DMAEA₃₃-g-(MMAi₈- 0.26 Gia-m₄o co-CHMA₂))]₃ quaternized

with Mel (40%)

p[(DMAEA₃₃-g-(MMA₁₈- 0.07 Gia-fio co-CHMA₂))]₃ quaternized

with HFI (10%)

p[(DMAEA₃₃-g-(MMA₁₈- 0.68 G_la-fioo co-CHMA₂))]₃ quaternized

with HFI (100%)

p[(DMAEAio-g-(MMA₁₈- 0.39 Gib Gib-m₉9 co-CHMA2))]2.₅ quaternized

with Mel (99%)

p[(DMAEAi₀-g-(MMA₁₈- 0-10 Gib-f₂₆ c -CHMA₂))]_{2 5} quaternized

with HFI (26%)

p[(DMAEA₃₂-g-(MMA₃₅- 0.52 MM₂ G_2a G_2a-m9₄ CO-CHMA6))]!.5 quaternized

with Mel (94%)

p[(DMAEA₃₂-g-(MMA₃₅- 0.23 G_2a-f42 co-CHMA₆))] i.₅ quaternized

with HFI (42%)

p[(DMAEAi₆-g-(MMA₃₅- 0.38 G2b G2b-m₁oo co-CHMA₆))]i.₅ quaternized

with Mel (100%)

p[(DMAEA₁₆-g-(MMA₃₅- 0.08 G2b-f2i co-CHMA₆))]_{1 5} quaternized

with HFI (21%)

a Degree of quatemization determined from the ratio of unquatemized (2.65 ppm) and quaternized (3.40 ppm) a-amino methyl proton integrals (Mel) in D2019, 26 or integral of unquatemized (2.13 ppm) and quaternized (3.04 ppm) a-amino methyl proton integrals (FHI) in DMSO-<¾24, 25 ^b Based on mole fraction of DMAEA in graft copolymer and degree of quatemization. Application of quaternized polymer coatings. The polymers of Table 3 were applied directly to polycarbonate substrates using a bar applicator to a standard polycarbonate substrate at a range of different thicknesses from a water/ethanol solvent mixture. These coatings were then dried overnight at 20 °C in a vacuum oven. The properties of these coatings were investigated in terms of their anti-static and anti-fogging properties.

Anti-static and Anti-dust Properties. In order for a material to be deemed 'anti-static' or 'anti-dust', it must be able to dissipate charge. This can be measured using surface resistivity or static decay measurements. The surface resistivity of a material is defined as the resistance to the flow of electrical current across the surface of the material. Insulators, such as polycarbonate, have surface resistivities in the realm of 10¹⁶-10¹⁸ Ohms/sq, whereas a conducting material has a lower resistivity of 10⁴-10⁶ Ohms/sq. Materials with anti-static or anti-dust properties tend to have surface resistivities between 10⁹-10¹² and 10¹²-10¹⁴ Ohms/sq respectively.

The surface resistivity of a range of coated polycarbonates (Table 4) were tested for selected coatings as a technique to determine the viability of these coatings to act as anti-static or anti-dust agents. As a reference point, uncoated PC has a surface resistivity of 10¹⁸ Ohms/sq. The measured coatings all have a much lower surface resistivity than that of uncoated PC (Table 4), demonstrating an improvement of the anti-static and anti-dust properties. The suitability of the coatings for use as anti-static and anti-dust additives can also be measured by determining the static decay half- life of the material, i.e. the time it takes for half an applied static charge to be dissipated over the surface of the material. Polycarbonate is an insulator, and therefore untreated polycarbonate has a very long static decay half-life (ti/2). Measurement of ti/2 after application of a coating from a polymer synthesized in Table 3, clearly shows that the surface of the PC has been modified (Table 4). For a surface of a material to be considered an 'anti-dust', a ti/2 < 60 seconds is suggested. Almost all of the coatings fall in a region considered suitable for anti-dust applications, which is in agreement with surface resistivity measurements. Table 4. Anti-static properties of quaternized polymers.

Gla-m97^b 10 1.60x10" 1 1 ✓

100 9.72xl0⁹ <1 ✓

680 8.79xl0¹⁰ <1 ✓

2000 5.24xl0¹⁰ <1 ✓ ✓

7000 5.80xl0¹⁰ <1 ✓ ✓

10000 5.47xl0¹⁰ <1 ✓ ✓

Gia-nW 100 1.60xlO^u <1 ✓ ✓

Gia-nW 100 4.26x10" <1 ✓ ✓

Gib-nW 100 1.43xl0¹⁰ <1 ✓ ✓

2000 9.89xl0¹⁰ <1 ✓ ✓

7000^f - 3.0 - ✓

10000^f - 2.0 - ✓

G_2a-m9₄ ^c 100 1.42xl0¹⁰ <1 ✓

2000 1.29x10" <1 ✓ ✓

7000 - <1 - ✓

10000 - <1 - ✓

G₂b-mioo^c 100 1.61xl0¹⁰ <1 ✓ ✓

2000 3.1 1x10" <1 ✓ ✓

7000 - 1.6 - ✓

10000 - 2.0 - ✓

Gia-fio^d 1800 8.01xl 0¹² 1 1.5 X ✓

6300^g 1.30xl0¹³ 9.1 X ✓

9000^g 6.64xl0¹² 9.8 X ✓

Gla-fl00^d 100 6.79x10° 18 X ✓

Gib-f₂₆ ^d 1800^f 8.23xl0¹³ 35.2 X ✓

6300^f - 28 - ✓

9000^f - 20 - ✓

G_2a-f₄2^e 1800 3.80xl0¹³ 19 X ✓

6300 - 24 - ✓

9000 - 22 - ✓

G₂b- 2i^e 1800^h 2.03xl0¹⁴ 1 17 X X

6300^h 3.63xl0¹⁵ 2893 X X

9000^h - 1419 X X a Theoretical fdm thickness based on applicator size and solid content; ^b 1 g polymer dissolved in 6 g water and 3 g ethanol; ⁰ 1 g polymer dissolved in 3 g ethanol and 6 g water; ^d lg polymer dissolved in 5 g water and 5 g ethanol; ^e 1 g polymer dissolved in 2.5 g water and 7.5 g ethanol; ^f Minor cracking of film; ^s patchy coverage of coating; ^h hazy film. The degree and type of quaternization was also investigated. In order for a material to be considered suitable for anti-dust applications, a surface resistivity of 10¹² - 10¹⁴ Ohms/sq is required. The polymers (partially) quaternized with FHI all fall within this range, barring G2t>-f2i . The polymers (fully) quaternized with Mel, on the other hand, show even lower surface resistivities (10¹⁰ - 10¹¹ Ohms/sq) which classifies them as anti-static materials. Again these results are confirmed by static decay measurement which show that in fact the polymers quaternized with Mel all show very short ti/2, with many dissipating the charge in less than a second. On the other hand, polymers quaternized with FHI show longer decay half-lives (> 9 seconds) but are still considered acceptable for anti-dust applications.

Higher degrees of quaternization with FHI (Gia-fioo) show a slight improvement in the surface resistivity behaviour with values reaching 6.79 ^χ 10¹³ Ohms/sq, however it does not approach the low values obtained using Mel as a quaternizing agent with similar degrees of quaternization (Table 4). There is a distinct trend in surface resistivity depending on the degree of quaternization: that with higher degrees of quaternization lower surface resistivities are measured.

Anti-fogging Properties. The coated plaques, described in the previous section, were tested for their anti-fogging properties using a simple test. By breathing on the coated plaques and comparing to untreated polycarbonate it was very clear that the coated substrates show anti-fogging properties; the coated polycarbonate remained transparent whereas uncoated polycarbonate showed signs of 'fog', turning opaque. In order to provide quantitative evidence of the anti-fog properties, the contact angle of water on the substrate surface was measured.

Firstly, the contact angle was measured over time using a sessile drop method. An initial contact angle of < 40° is desired for anti-fogging applications, although a contact angle of < 20° is preferred. A list of the contact angles for many of the coatings is shown in Table 5; the contact angle at the start of the measurement (t=0), as well as the time until the contact angle reaches 40° and 20° are also displayed in the table. For reference, PC is decidedly hydrophobic with an initial contact angle of 88° which does not fall below 40° even in excess of 160 seconds (at which point evaporation can start to influence the measurement).

Table 5. Anti-fogging properties of quaternized polymers.

Time until Time until

Dry Film Contact Dynamic

Contact Contact

Thickness angle at Contact angle angle angle

/nm t=0/° (Adv./Rec.)/°

<40 sec <20 sec

PC - 88 >160 >160 84/70

G_la-ni9₇ ^a 10 34 1 10 45/28

100 52 0.3 5 <20/<20

680 63 1 21 52/28

2000 48 9 80 100/58

10000 58 76 >160 85/53

Gia-m₆o^a 100 81 0.5 5 71/52

Gia-m₄₀ ^a 100 78 0.5 5 98/66

Gib-m99^a 100 46 0.1 1 1 33/23

2000 57 5 67 49/34

G_2a-ni9₄ ^b 100 44 0.1 2.5 <20/<20

2000 52 7 66 60/32

7000 51 6 90 67/30

10000 45 7 79 63/33

G₂b-mioo 100 43 0.1 2 24/19

2000 45 2 40 45/25

7000 42 1 70 42/24

10000 53 1 145 51/28

Gla-fl0° 1800 1 14 >160 >160 137/120

6300^f 117 >160 >160 115/97

Gla-flOO^C 100 95 >160 >160 88/72

Gib-f26^c 1800^e 83 49 90 91/56

G_2a-f42^d 1800 85 32 >160 109/75

G_2b-f₂i^d 1800^g 93 >160 >160 90/58

a 1 g polymer dissolved in 6 g water and 3 g ethanol; ^b 1 g polymer dissolved in 3 g ethanol and 6 g water; ^c lg polymer dissolved in 5 g water and 5 g ethanol; ^d 1 g polymer dissolved in 2.5 g water and 7.5 g ethanol; ^e Minor cracking of film; ^f patchy coverage of coating; ^g hazy film.

Initially, thicker coatings (20 - 100 pm) were made and tested. At all film thicknesses, a contact angle of > 40° is observed directly after the droplet has been placed on the coated substrate, although in all cases the contact angle is less than that of uncoated PC. However, unlike PC which remains at 88° over time (disregarding the effects of evaporation), the contact angle of water on the coated substrates decreases over time as the droplet spreads out over the substrate surface. In fact, at a dry film thickness of 20 μητι, the contact angle of PC coated in Gia-17197 decreases rapidly from 48° to 40° in 9 seconds, then falls further to 20° within 80 seconds.

Claims

A graft copolymer comprising a main chain and at least one graft linked to the main chain, wherein

- the main chain comprises a polymer selected from the group of poly((A/,/V- dialkylamino)alkyl acrylate), poly((/V,A/-dialkylamino)alkyl methacrylate), poly((/V,/V-dialkylaminoalkyl)styrene) and copolymers comprising two or more different monomers selected from the group of (A/,A/-dialkylamino)alkyl acrylates, (/V,/V-dialkylamino)alkyl methacrylates and (Λ/,Λ/- dialkylaminoalkyl)styrene; and wherein

- the at least one graft comprises a polymer selected from the group of

poly(acrylate ester), poly(methacrylate ester), polyacrylamide,

poly(methacrylamide), polystyrene, polyalkylene, and copolymers

comprising two or more different monomers selected from the group of acrylate ester, methacrylate ester, acrylamides, methacrylamides, styrenes and alkylenes.

A graft copolymer according to claim 1 , wherein the

poly((A/,/V-dialkylamino)alkyl acrylate) is selected from the group of

poly((/V,A/-dialkylamino)ethyl acrylate), poly((A/,/V-dialkylamino)propyl acrylate) and poly((/V,A/-dialkylamino)butyl acrylate), in particular from the group of poly(2-(A/,A/-dimethylamino)ethyl acrylate), poly(3-(/V,A/-dimethylamino)n- propyl acrylate) and poly(4-(/V,/V-dimethylamino)n-butyl acrylate).

A graft copolymer according to claim 1 or 2, wherein the poly(alkyl acrylate) in the at least one graft is a copolymer, in particular a copolymer of cyclohexyl methacrylate and methyl methacrylate.

A graft copolymer according to any one of claims 1-3, wherein the molar mass of the poly(alkyl acrylate) in the at least one graft is in the range of 1 ,000- 10,000 g/mol, preferably in the range of 1 ,500-3,000 g/mol.

A graft copolymer according to any one of claims 1-4, wherein the average number of grafts per main chain is in the range of 1-10, preferably in the range of 1-3.

A graft copolymer according to any one of claims 1-5 having a number average molar mass (Mn) in the range of 4,000 to 40,000 g/mol, preferably in the range of 8,000 to 20,000 g/mol. / . quaiermzea gran copolymer, comprising a gran copolymer according to any one of claims 1-6, wherein the nitrogen atom of one or more of the N,N- dialkylamino groups is a quaternized nitrogen atom, wherein the quaternized nitrogen atom is part of a tri-alkyl-aryl ammonium group or a tetra-alkyl ammonium group, in particular a methyl-trialkyl-ammonium iodide group or a perfluorohexyl-trialkyl-ammonium iodide group.

8. A quaternized graft copolymer according to claim 7, wherein the degree of quaternization is in the range of 20-100%, preferably in the range of 50-100%.

9. A composition comprising a polymer and a quaternized graft copolymer

according to claim 7 or 8.

10. A composition according to claim 9, wherein the polymer is a polycarbonate, in particular an aromatic polycarbonate based on bisphenol A, more in particular a polycarbonate known as Lexan GLX143.

1 1. A method for preparing a graft copolymer, comprising

- preparing a macromonomer comprising (1) a carbon-carbon double bond that is capable of participating in a polymerization reaction with other carbon-carbon double bonds and (2) a

polymer of at least one monomer selected from the group of acrylate ester, methacrylate ester, acrylamide, methacrylamide, styrene and alkylene; then

- copolymerizing the macromonomer with a monomer selected

from the group of (A/,A/-dialkylamino)alkyl acrylate, (N,N- dialkylamino)alkyl methacrylate and (N,N- dialkylaminoalkyl)styrene to form a graft copolymer.

12. A method according to claim 11 , wherein the macromonomer is prepared by catalytic chain transfer polymerization.

13. A method according to claim 11 , wherein the macromonomer is prepared by connecting (1) an ethylenic compound selected from the group of acrylic acid or an ester forming derivative thereof, methacrylic ester or an ester forming derivative thereof and a styrene derivative having a halide substituent on the aromatic ring, with (2) a polymer of at least one monomer selected from the group of acrylate ester, methacrylate ester, acrylamide, methacrylamide, styrene and alkylene, which polymer is functionalized with an hydroxy end- group.

14. A method for preparing a quaternized graft copolymer, comprising

quaternizing the nitrogen atom of one or more of the /V,/V-dialkylamino groups of a graft copolymer according to any one of claims 1-6.

15. A method according to claim 14, wherein the quaternizing is performed with an aliphatic halide or an aromatic halide.