Patent ID: 7022809

Claim:
Polyimides for producing low-energy anchoring layers in nematic liquid-crystal cells, according to the following types: polyimide derived from 2,2′-bis (3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and from 3,3′-dihydroxy-4, 4′ diaminobiphenyl of formula I: in which the radicals R 1 and R 2 , which are identical or different, represent an alkyl, arylalkyl, heteroarylalkyl, (cycloalkyl)alkyl, fluoroalkyl or siloxane radical and n is between 1 and 20; polyimide derived from pyromellitic anhydride (PMDA) and from 2,2-bis (3-amino-4-hydroxyphenyl)hexafluoropropane (Bis-AP-AF) of formula II. in which the radicals R 3 and R 4 , which are identical or different, have the same meaning as R 1 and R 2 and n is between 1 and 20; and copolymers of polyimide (I) and of polyimide (II).