Thermotropic copolyesters of a series of aromatic diols with phenylterephthalic acid and 4,4′‐oxybisbenzoic acid

Wholly aromatic, liquid crystalline, main chain copolyesters derived from various linearly substituted aromatic diols with mixtures of 2‐phenylterephthalic acid and a nonlinear aromatic dicarboxylic acid, 4,4′‐oxybisbenzoic acid, were prepared by acidolysis condensation polymerization reactions and characterized for their liquid crystalline properties. The formation of a liquid crystalline phase at elevated temperatures was not prevented by the introduction of up to 50 mol % of the nonlinear diacid in the copolymers, and all of those copolyesters exhibited nematic liquid crystalline phases. Furthermore, the inclusion of a nonlinear monomer was not as effective as was the presence of a phenyl substituent in decreasing the melting transition of these copolymers. All of the copolymers had high glass transition temperatures and high thermal stabilities.