THE SYNTHESIS AND CHARACTERIZATION OF NOVEL THERMOTROPIC LIQUID-CRYSTALLINE POLY(ARYL ETHER KETONE)S

The synthesis and characterization of novel thermotropic liquid crysta lline poly(aryl ether ketone)s based on the reaction of a liquid cryst alline mesogen containing monomer, biphenol, and a crystal-disrupting substituted monomer, t-butyl- or phenyl-, hydroquinone with 4,4'-diflu orobenzophenone are described. Two families of copolymers-a biphenol/t -butylhydroquinone series of 90, 75, 50, 25, and 0% biphenol, and a bi phenol/phenylhydroquinone series of 75, 50, 25, and 0%-are evaluated. Thermotropic liquid crystalline behavior was observed in the copolymer s containing 50 and 75% biphenol. The first order and second order tra nsitions associated with melting, crystallization, thermotropic liquid crystalline mesophases, and glass transition temperatures (Tgs) of ea ch copolymer are investigated. The thermal transitions are correlated with optical microscopy and X-ray and/or electron diffraction characte ristics. It was observed that the Tg increases and end group concentra tion decreased after isothermal heat treatment indicative of further p olymerization. These materials are believed to be the first known ther motropic liquid crystalline poly(aryl ether ketone)s.