Photocrosslinkable polymers

A polymer of the general formula I:

• in which
• M1 and M1′denote a recurring monomer unit from the group:
• acrylate, methacrylate, 2-chloroacrylate, 2-phenylacrylate;
• acrylamide, methacrylamide, 2-chloroacrylamide and 2-phenylacrylamide which are optionally N-substituted by lower alkyl;
• vinyl ethers, vinyl esters, styrene derivatives, siloxanes;
• M2 denotes a recurring monomer unit from the group:
• acrylate, methacrylate, 2-chloroacrylate, 2-phenylacrylate, acrylamide, methacrylamide, 2-chloroacrylamide and 2-phenylacrylamide which are optionally N-substituted by lower alkyl;
• vinyl ethers, vinyl esters;
• straight-chain or branched alkyl esters of acrylic or methacrylic acid, allyl esters of acrylic or methacrylic acid, alkyl vinyl ethers or esters, phenoxyalkyl acrylates or phenoxyalkyl methacrylates or hydroxyalkyl acrylates or hydroxyalkyl methacrylates, phenylalkyl acrylates or phenylalkyl methacrylates, the alkyl radicals having 1 to 20 carbon atoms;
• acrylonitrile, methacrylonitrile, styrene, 4-methylstyrene or siloxanes;
• w, w1 and w2 are molar fractions of the comonomers with 0<w≦1, 0≦w1<1 and 0≦w2≦0.5;
• S1 and S1′, independently of one another, denote a spacer unit, wherein each spacer unit, independently, is a straight-chain or branched alkylene group —(CH2)r— which is optionally monosubstituted or polysubstituted by fluorine, chlorine or cyano, or a chain of the formula —(CH2)r—L—(CH2)s—, in which L denotes a single bond or a linking functional group, and r and s each represent an integer from 1 to 20 with the proviso that r+s is ≦24;
• D, D′, independently of one another, denote —O— or —NR2—;
• in which R2 denotes hydrogen or lower alkyl;
• X, X′, Y and Y′, independently of one another, denote hydrogen, fluorine, chlorine, cyano, alkyl having 1 to 12 carbon atoms which is optionally substituted by fluorine and in which a CH2 group or a plurality of non-neighboring CH2 groups may optionally be replaced by O, —COO—, —OOC— and/or —CH═CH—;
• A and A′, independently of one another, denote phenylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, cyclohexane-1,4-diyl, piperidine-1,4-diyl or piperazine-1,4-diyl which is unsubstituted or optionally substituted by fluorine, chlorine, cyano, alkyl, alkoxy or fluoroalkoxy;
• B and B′, independently of another, denote phenylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, 1,4- or 2,6-naphthylene, 1,3-dioxane-2,5-diyl or cyclohexane-1,4-diyl which is unsubstituted or optionally substituted by fluorine, chlorine, cyano, alkyl, alkoxy or fluoroalkoxy;
• C and C′, independently of one another, denote phenylene which is unsubstituted or optionally substituted by fluorine, chlorine, cyano, alkyl, alkoxy or fluoroalkoxy, or pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,5-thiophenylene, 2,5-furanylene or 1,4- or 2,6-naphthylene;
• K and K′, independently of one another, denote hydrogen, fluorine, chlorine, cyano, nitro or a straight-chain or branched alkyl, alkoxy, alkyl-COO, alkyl-CO—NR3 or alkyl-OCO group having 1 to 20 carbon atoms which is optionally substituted by fluorine, chlorine, cyano or nitro and in which one CH2 group or a plurality of non-neighboring CH2 groups may optionally be replaced by —O—, —CH═CH— or —C|C— and in which R3 denotes hydrogen or lower alkyl;
• with the proviso that at least one of the rings A, B and C and/or at least one of the rings A′, B′ and C′ represents a phenylene radical which is substituted in the ortho or meta position to one of the linkage points by at least one alkoxy group or fluoroalkoxy group, and, if K denotes alkoxy or fluoroalkoxy, at least one of the rings A, B and C and/or at least one of the rings A′, B′ and C′ represents a phenylene radical which is substituted by at least one further alkoxy group or fluoroalkoxy group;
• Z, Z′, Z1 and Z1′, independently of one another, denote a single covalent bond, —(CH2)t—, —O—, —CO—, —CO—O—, —O—OC—, —NR4—, —CO—NR4—, —R4N—CO—, —(CH2)u—O—, —O—(CH2)u—, —(CH2)u—NR4— or —NR4—(CH2)u—;
• in which R4 denotes hydrogen or lower alkyl;
• t denotes an integer from 1 to 4;
• u denotes an integer from 1 to 3;
• and
• p, p′, n and n′, independently of one another, denote 0 or 1 excluding compounds wherein, simultaneously,
• n=p=0;
• w=1;
• M1=acrylate, acrylamide, methacrylate or methacrylamide;
• S1=straight chain alkylene;
• D=O or NH;
• X=Y=H;
• and
• C=dimethoxy-substituted phenylene.