Claims
- 1. A polyamic acid for inducing alignment of a liquid crystal medium adjacent to a surface of an optical alignment layer comprising a polyamic acid of structure I ##STR26## wherein R.sub.1 is selected from the group of C.sub.3 -C.sub.20 linear or branched hydrocarbon chain containing 1 to 4 carbon-carbon double bonds; X is a divalent moiety selected from the group --O--, --S--, and --NR--, wherein R is selected from H, R.sub.1, and C.sub.1 -C.sub.4 hydrocarbon chain; X.sub.1 is independently selected from the group H, Cl, F, and Br; m is 1 or 0; Z is selected from the group --S--, --O--. --SO.sub.2 --, --CH.sub.2 --, --C(CF.sub.3).sub.2 --, --C(O)--. --CH.sub.2 CH.sub.2 --, --NR.sub.2 -- and a covalent bond wherein R.sub.2 is selected from H and C.sub.1 -C.sub.4 hydrocarbon chain; and the carboxylic acid groups are ortho to the amide linkages.
- 2. A polyamic acid of claim 1 wherein R.sub.1 is a C.sub.10 -C.sub.20 linear or branched hydrocarbon chain with containing 2 to 4 carbon-carbon double bonds.
- 3. A polyamic acid of claim 2 wherein R.sub.1 is selected from the group of geranyl, citronellyl and farnesyl.
- 4. A polyamic acid of claim 1 wherein X is --NR--.
- 5. A polyamic acid of claim 1 wherein m is 0 and X.sub.1 is H or Cl.
- 6. A polyamic acid of claim 1 that is a copolymer additionally comprising structure II ##STR27## wherein X.sub.2 is selected from the group H, C.sub.1 -C.sub.4 hydrocarbon, --CN, --CF.sub.3, F, Cl, Br, I, --NO.sub.2, --OR.sub.2, --CO.sub.2 R.sub.2, and --CO.sub.2 N(R.sub.2).sub.2, wherein R.sub.2 is H or a C.sub.1 -C.sub.4 hydrocarbon.
- 7. An optical alignment layer comprising a polyimide derived from the polyamic acid of claim 1.
- 8. A liquid crystal display element comprising the optical alignment layer of claim 7.
Government Interests
This invention was made with United States Government support under Agreement No. MDA972-93-2-0014 awarded by ARPA. The United States Government has certain rights in the invention.
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