Wholly aromatic thermotropic liquid crystalline polyesters of 4,4′‐biphenol, substituted biphenols, and 1,1′‐binaphthyl‐4,4′‐diol with 3,4′‐benzophenone dicarboxylic acid

Abstract

AbstractWholly aromatic, thermotropic homopolyesters, derived from 4,4′‐biphenol, substituted biphenols, or 1,1′‐binaphthyl‐4,4′‐diol and 3,4′‐benzophenone dicarboxylic acid, and two copolyesters, each of which contained 30 mol % of 6‐hydroxy‐2‐naphthoic acid, were prepared by acidolysis polycondensation reactions and characterized for their liquid crystalline properties. The solubility behavior of these polymers has also been investigated. The two homopolymers of phenyl‐substituted biphenols with 3,4′‐benzophenone dicarboxylic acid were soluble in many common organic solvents. All of the homopolymers had lower Tm/Tf values than those with terephthalic acid, which was attributed to the incorporation of the asymmetric 3,4′‐benzophenone dicarboxylate units in a head‐to‐head and head‐to‐tail fashion along the polyester chain. Two copolymers had lower Tm values than those of the respective homopolymers, as expected. They formed nematic phases which persisted up to 400°C, except those of phenyl‐substituted biphenols with 3,4′‐benzophenone dicarboxylic acid. Each of these two polymers also exhibited an accessible Ti transition, and had a broad range of LC phase. They had glass transition temperatures, Tg, in the range of 139‐209°C and high thermal stabilities in the temperature range of 465‐511°C. © 1995 John Wiley & Sons, Inc.