PHOTOACTIVE POLYIMIDES POLYAMIDE ACIDS OR ESTERS THEREOF WITH SPECIFIC SIDE CHAIN PHOTOCROSSLINABLE GROUPS AS ORIENTATION LAYERS FOR LIQUID CRYSTALS

摘要

A photoactive polymer from the class of polyimides, poiyamide acids and esters thereof, characterised in that it comprises as a side-chain a photocrosslinkable group of the general formula I: Qv Y wherein the broken line indicates the point of linkage to the polyimide main chain and wherein: A represents pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,5-thiophenylene, 2,5-furanylene, 1,4- or 2,6-naphthylene, or phenylene; optionally substituted by a group selected from fluorine, chlorine, cyano or by a Ci-18 cyclic, straight-chain or branched alkyl residue, which is optionally substituted by a single cyano group or by one or more halogen atoms and in which one or more non-adjacent alkyl -CHr- groups are optionally replaced by a group Q; B is a straight-chain or branched alkyl residue which is unsubstituted, mono-substituted by cyano or halogeno, or poly-substituted by halogeno, having 3 to 18 carbon atoms, wherein one or more non-adjacent CB.2 groups may independently be replaced by a group Q; C1 and C2 each independently of the other represents an aromatic or alicyclic group which is unsubstituted or substituted by fluorine, chlorine, cyano, or by a cyclic, straight-chain or branched alkyl residue which is unsubstituted, mono-substituted by cyano or halogeno, or poly-substituted by halogeno, having 1 to 18 carbon atoms and wherein one or more non-adjacent CH? groups may independently be replaced by a group Q; 5 D represents an oxygen atom or -NR1- wherein R1 represents a hydrogen atom or lower alkyl; S1 and S2 each independently of the other represent a single covalent bond or a spacer unit; S3 represents a spacer unit: Q represents a group selected from -0-, -CO-, -CO-0-, -0-CO-, -Si(CH3)2-0-Si(CH3)2- -NR1-, -NR'-CO-, -CO-NR1--N^-CO-O-, -O-CO-NR1-, -NR'-CO-NR1-, -CH=CH-, -C=C-and -0-CO-O-, wherein R1 represents a hydrogen atom or lower alkyl; n1 and n2 are each independently 0 or 1; and X, Y each independently of the other represents hydrogen, fluorine, chlorine, cyano, alkyl optionally substituted by fluorine having from 1 to 12 carbon atoms in which optionally one or more non-adjacent CEb groups are replaced by -0-, -CO-0-, -O-CO- and/or -CH=CH-