SYNTHESIS AND CHARACTERIZATION OF NOVEL THERMOTROPIC LIQUID-CRYSTALLINE COPOLY(ESTER IMIDE)S

Novel liquid crystalline copoly(ester imide)s were synthesized via pol yesterification of triethyleneglycol bis(4-carboxyphenyl) ether (le), diacetoxybiphenyl, and diacids with imide moieties. The effects of com position on the changes of T-g, T-m, and T-i were examined by global T SC and DSC. Thermal gravimetric analyses (TGA) found that 4a-d and 5a- g possess higher thermal stability. Strong stir opalescence phenomenon and observations from polarized optical microscopy identified that 2b -e and 3a-d possess the typical schlieren texture of an enantiotropic nematic mesophase. The birefrigent melts of 4a-d and 5a-g, however, di splayed particular liquid crystalline behavior. Copolymers with higher aromatic imide ring content (4a-d, 5a-g) farm a layered structure and an enantiotropic smectic mesophase in the melting state. The melt vis cosity of the semetic mesophase was higher than the nematic mesophase which was observed by capillary rheometer. (C) 1998 John Wiley & Sons, Inc.