Synthesis and properties of novel aromatic polyhydrazides and poly(amide-hydrazide)s based on the bis(ether benzoic acid)s from hydroquinone and substituted hydroquinones

4,4'-(1,4-Phenylenedioxy)dibenzoic acid as well as the 2-methyl-, 2-tert-bu tyl-, or 2-phenyl-substituted derivatives of this dicarboxylic acid were sy nthesized in two main steps from p-fluorobenzonitrile and hydroquinone or i ts methyl-, tert-butyl-, or phenyl-substituted derivatives. Polyhydrazides and poly(amide-hydrazide)s were prepared from these bis(ether benzoic acid) s or their diacyl chlorides with terephthalic dihydrazide, isophthalic dihy draside, or p-aminobenzoyl hydrazide by means of the phosphorylation reacti on or low-temperature solution polycondensation. Most of the hydrazide poly mers and copolymers are amorphous and readily soluble in various polar solv ents such as N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide. They coul d be solution-cast into transparent, flexible, and tough films. These polyh ydrazides and poly(amide-hydrazide)s had T(g)s in the range of 167-237 degr ees C and could be thermally cyclodehydrated into the corresponding poly(1, 3,4-oxadliazole)s and poly(amide-1,3,4-oxadiazole)s approximately in the re gion of 250-350 degrees C, as evidenced by the DSC thermograms. All the ter t-butyl-substituted oxadiazole polymers and those derived from isophthalic dihydrazide were organic soluble. The thermally converted oxadiazole polyme rs exhibited T(g)s in the range of 208-243 degrees C and did not show signi ficant weight loss before 450 degrees C either in nitrogen or in air. (C) 1 999 John Wiley C Sons, Inc.