Process and materials for inducing pre-tilt in liquid crystals and liquid crystal displays

A liquid crystal display element made from a polyimide composition which is the reaction product of at least one diaryl ketone tetracarboxylic dianhydride, at least one hydrophobic diamine and at least one, diaminobenzophenone, which comprises at least two structural elements of the formulas IV and VII ##STR46## wherein Y is a divalent radical selected from the formulas II and III ##STR47## wherein Z is selected, independently, from the group consisting of --S--, --O--, --SO.sub.2 --, --CH.sub.2 --, --C(CF).sub.2 --, --C(O)--, --CH.sub.2 CH.sub.2 --, --NR-- and a covalent bond wherein R is C.sub.1 -C.sub.4 hydrocarbon chain;

• X is independently selected from R.sub.1, --O--R.sub.1, --S--R.sub.1, --N(R.sub.2)--R.sub.1 ;
• wherein R.sub.1 is independently selected from C.sub.3 -C.sub.20 perfluorinated alkyl chain, C.sub.4 -C.sub.20 partially fluorinated alkyl chain, and C.sub.10 -C.sub.20 hydrocarbon chain;
• X.sub.1 is independently selected from X and H;
• R.sub.2 is selected, independently, from H, C.sub.1 -C.sub.9 hydrocarbon chain and R.sub.1 ;
• X.sub.2 is independently selected from the group consisting of H, CL, F, Br, R.sub.3 and R.sub.3 O--, wherein R.sub.3 is independently selected from C.sub.1 -C.sub.3 perfluorinated alkyl chain, C.sub.1 -C.sub.3 partially fluorinated alkyl chain and C.sub.1 -C.sub.8 hydrocarbon chain;
• and m is 1 or 0.

A liquid crystal display element made from a polyimide composition, derived from a diamine component and a dianhydride component, for generating pre-tilt in alignment of a liquid crystal medium comprising a copolyimide derived from least one alicyclic tetracarboxylic dianhydride, at least one hydrophobic diamine and at least one diaminodibenzophenone, which comprises at least two structural elements of the formulas V and VIII ##STR48## herein Y is a divalent radical selected from the formulas II and III ##STR49## wherein Z is selected from the group consisting of --S--, --O--, --SO.sub.2 --, --CH.sub.2 --, --C(CF.sub.3).sub.2 --, --C(O)--, --CH.sub.2 CH.sub.2 --, --NR-- and a covalent bond wherein R is a C.sub.1 -C.sub.4 hydrocarbon chain;

• X is independently selected from R.sub.1, --O--R.sub.1, --S--R.sub.1, --N(R.sub.2)--R.sub.1 ;
• wherein R.sub.1 is independently selected from C.sub.4 -C.sub.20 perfluorinated alkyl chain, C.sub.4 -C.sub.20 partially fluorinated alkyl chain, and C.sub.10 -C.sub.20 hydrocarbon chain;
• X.sub.1 is independently selected from X and H;
• R.sub.2 is selected, independently, from H, C.sub.1 -C.sub.9 hydrocarbon chain and R.sub.1 ;
• X.sub.2 is independently selected from the group consisting of H, CL, F, Br, R.sub.3 and R.sub.3 O--, wherein R.sub.3 is independently selected from C.sub.1 -C.sub.3 perfluorinated alkyl chain, C.sub.1 -C.sub.3 partially fluorinated alkyl chain and C.sub.1 -C.sub.8 hydrocarbon chain;
• and P is a tetravalent organic radical derived from said alicyclic tetracarboxylic dianhydride containing at least four carbon atoms, no more than one carbonyl group of the dianhydride being attached to any one carbon atom of the tetravalent radical.

A liquid crystal display element made from a polyimide composition which is the reaction product of at least one diaryl ketone tetracarboxylic dianhydride, at least one hydrophobic diamine and at least one diamine derived from a radical Y.sub.2, comprising at least one structural element of the formulas IV and IVa ##STR50## wherein Y is a divalent radical selected from the formulas II and III ##STR51## wherein Z is selected, independently, from the group consisting of --S--, --O--, --SO.sub.2 --, --CH.sub.2 --, --C(CF.sub.3).sub.2 --, --C(O)--, --CH.sub.2 CH.sub.2 --, --NR-- and a covalent bond wherein R is a C.sub.1 -C.sub.4 hydrocarbon chain;

• X is independently selected from R.sub.1, --O--R.sub.1, --S--R.sub.1, --N(R.sub.2)--R.sub.1 ;
• wherein R.sub.1 is independently selected from C.sub.4 -C.sub.20 perflourinated alkyl chain, C.sub.4 -C.sub.20 partially fluorinated alkyl chain, and C.sub.10 -C.sub.20 hydrocarbon chain;
• X.sub.1 is independently selected from X and H;
• R.sub.2 is selected, independently, from H, C.sub.1 -C.sub.9 hydrocarbon chain and R.sub.1 ;
• X.sub.2 is independently selected from the group consisting of H, CL, F, Br, R.sub.3 and R.sub.3 O--, wherein R.sub.3 is independently selected from C.sub.1 -C.sub.3 perfluorinated alkyl chain, C.sub.1 -C.sub.3 partially fluorinated alkyl chain and C.sub.1 -C.sub.8 hydrocarbon chain;
• m is 1 or 0;
• and Y.sub.2 is a divalent radical selected from the formulas IIa and IIIa ##STR52## wherein X.sub.3 is independently selected from C.sub.1 -C.sub.3 perfluorinated alkyl chain, partially fluorinated alkyl chain or --OCF.sub.3 ;
• and X.sub.4 is independently selected from X.sub.3 and H.