LC-polyimides 26. Photoreactive,nematic or cholesteric poly(ester-imide)s derived from 4-aminocinnamic acid trimellitimide,isosorbide and various diphenols

Abstract

A photoreactive and mesogenic dicarboxylic acid was prepared from 4-aminocinnamic acid and trimellitic anhydride. Its dichloride was polyeondensed with isosorbide and methylhydroquinone, phenylhydroquinone, 4,4'-dihydroxydilhenylether or 1.644'-dihy-droxyphenoxy)hexan. The copolyesters containing < 50 mol% of isosorbide form a cholesteric melt and the homopolyesters of the diphenols are nematie. WAXD powder patterns and DSC measurements agree in that all four homopoly(ester-imide)s are semicrystalline. Incorporation of isosorbide reduces and finally eliminates the crystallinity. The solid state of these copoly(ester-imide)s is a cholesteric glass. Copolyesters containing phenylhydroquinone and 5-10 mol% of isosorbide exhibit a Grandjean texture above 250C. The poly(ester-imide)s of unsubstituted diphenols undergo thermal cross-linking above 350C and all poly(ester-imide)s are sensitive to photocross-linking upon irradiation at wavelengths <360 nm.