FULLY AROMATIC THERMOTROPIC LIQUID-CRYSTALLINE POLYESTERS OF 3,4'-DIHYDROXYBENZOPHENONE

A series of fully aromatic, thermotropic polyesters, derived from 3,4' -dihydroxybenzophenone and various aromatic dicarboxylic acids, was pr epared by the high-temperature solution polycondensation method and ex amined for thermotropic behavior by a variety of experimental techniqu es. The aromatic dicarboxylic acids used in this study were 2,6-naphth alenedicarboxylic acid, 4,4'-bibenzoic acid, and terephthalic acid. Th e two homopolymers of 3,4'-DHB with either 2,6-NDA or 4,4'-BBA formed nematic LC phases at 285 degrees C and 255 degrees C and also exhibite d isotropization transitions (T-i) at 317 degrees C and 339 degrees C, respectively. The copolymer of 3,4'-DHB with 50% TA and 50% 2,6-NDA a lso formed a nematic LC phase and had a broader range of LC phase than that of its respective homopolymers. Two other copolymers of 3,4'-DHB , both containing 50% 4,4'-BBA, also formed nematic LC phases at low T -f values. All of the thermotropic polyesters had high thermal stabili ties. (C) 1994 John Wiley & Sons, Inc.