S. Hsiao, Liang-Ru Dai, M. He
Apr 15, 1999
Citations
0
Influential Citations
25
Citations
Journal
Journal of Polymer Science Part A
Abstract
4,4′-(1,4-Phenylenedioxy)dibenzoic acid as well as the 2-methyl-, 2-tert-butyl-, or 2-phenyl-substituted derivatives of this dicarboxylic acid were synthesized in two main steps from p-fluorobenzonitrile and hydroquinone or its 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 dihydrazide, or p-aminobenzoyl hydrazide by means of the phosphorylation reaction or low-temperature solution polycondensation. Most of the hydrazide polymers and copolymers are amorphous and readily soluble in various polar solvents such as N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide. They could be solution-cast into transparent, flexible, and tough films. These polyhydrazides and poly(amide–hydrazide)s had Tgs in the range of 167–237°C and could be thermally cyclodehydrated into the corresponding poly(1,3,4-oxadiazole)s and poly(amide–1,3,4-oxadiazole)s approximately in the region of 250–350°C, as evidenced by the DSC thermograms. All the tert-butyl-substituted oxadiazole polymers and those derived from isophthalic dihydrazide were organic soluble. The thermally converted oxadiazole polymers exhibited Tgs in the range of 208–243°C and did not show significant weight loss before 450°C either in nitrogen or in air. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1169–1181, 1999