Synthesis and properties of new aromatic poly(ether benzoxazole)s from 2,2′-bis(4-amino-3-hydroxyphenoxy)biphenyl and aromatic dicarboxylic acid chlorides

A new bis(o-aminophenol) with a crank and twisted noncoplanar structure and ether linkages, 2,2'-bis(4-amino-3-hydroxyphenoxy)biphenyl, was synthesized by the reaction of 2-benzyloxy-4-fluoronitrobenzene with biphenyl-2,2'-diol, followed by reduction. Biphenyl-2,2'-diyl-containing aromatic poly(ether benzoxazole)s with inherent viscosities of 0.52-1.01 dL/g were obtained by a conventional two-step procedure involving the polycondensation of the bis(o-aminophenol) monomer with various aromatic dicarboxylic acid chlorides, yielding precursor poly(ether o-hydroxyamide)s, and subsequent thermal cyclodehydration. These new aromatic poly(ether benzoxazole)s were soluble in methanesulfonic acid, and some of them dissolved in m-cresol. The aromatic poly(ether benzoxazole)s had glass-transition temperatures of 190-251 degreesC and were stable up to 380 degreesC in nitrogen, with 10% weight losses being recorded above 520 degreesC. (C) 2002 Wiley Periodicals, Inc.