Synthesis and properties of liquid crystalline copolyarylates containing phenylhydroquinone

Copolycondensations of TPA, PhHQ, and several aromatic diacid and diol modi fiers were examined for which kind of the modifiers incorporated is more ef fective to reduce the transition temperatures of the resulting copolyesters and how they affect the temperatures. The acid modifiers are more effectiv e than the diol ones, significantly when they have substituents. As another type of modifier, HBA forming the ester bond of an AB structure different from the AABB structure of TPA/PhHQ polyester was also effective, and the l owering effect on the temperatures was varied by the mode of copolycondensa tions, being most remarkable when HBA was randomly introduced. The results obtained were discussed in terms of the disturbance and thereby weakening o f the interchain dipole-dipole interaction between the carbonyl groups in t he ester linkages due to the introduction of the diacid modifiers and of HB A having an ester bond of a different directionality. (C) 1999 John Wiley & Sons, Inc.