LC-Polyimides. 22. Thermotropic Poly(Amide-Imide)s Derived from New Bisimide Spacers and Biphenyl-4,4′-dicarboxylic Acids

Abstract

A new class of diamine spacers was synthesized from α,ω-diaminoalkanes and 4-nitrophthalic anhydride. The resulting α,ω-bis(4-aminophthalimido)alkanes were polycondensed with terephthaloylchloride, 2-phenylthioterephthaloylchloride, naphthalene-2,6-dicarboxylic acid dichloride, and 4,4′-biphenyl dicarboxylic acid dichloride. Most poly(amide-imide)s proved to be semicrystalline, forming a smectic layer structure in the solid state. Yet only the poly(amide-imide)s derived from 4,4′-biphenyl dicarboxylic acid are thermotropic and form a smectic and a nematic LC-phase. Due to the high temperatures employed, the reversibility of the phase transitions suffers from thermal degradation.