THE SYNTHESIS AND THERMOTROPIC LIQUID-CRYSTALLINE BEHAVIOR OF NOVEL MAIN-CHAIN POLY(ARYL ETHER KETONE)S CONTAINING A LATERAL PHENYL GROUP

Novel main chain poly(aryl ether ketone)s containing a lateral phenyl group were synthesized by nucleophilic substitution reactions of 4,4'- biphenol and phenylhydroquinone with either 4,4'-difluorobenzophenone or 1,4-bis(4-fluorobenzoyl)benzene and their thermotropic liquid cryst alline properties were characterized by a variety of experimental tech niques. Thermotropic liquid crystalline behaviour was observed in the copolymers containing 50 and 70mol% biphenol. Melting (T-m) and isotro pization (T-i) transitions both appeared on the DSC thermograms. A ban ded texture was formed after shearing the sample in the liquid crystal line nematic state. As expected, each of the copolymers had a relative ly lower melting transition than the biphenol-based homopoly(aryl ethe r ketone)s because of the copolymerization effect of the crystal-disru pting monomer phenylhydroquinone.