Three new bis(ether-acyl chloride) monomers, 1,1-bis[4-(4-chloroformylphenoxy)phenyl]cyclohexane (1a), 5,5-bis[4-(4-chloroformylphenoxy)phenyl]-4,7-methanohexahydroindan (1b), and 9,9-bis[4-(4-chloroformylphenoxy)phenyl]fluorene (1c), were synthesized from readily available compounds. Aromatic polybenzoxazoles bearing ether and cardo groups were obtained by the low-temperature solution polycondensation of the bis(ether-acyl chloride)s with three bis(aminophenol)s and the subsequent thermal cyclodehydration of the resultant poly(o-hydroxy amide)s. The intermediate poly(o-hydroxy amide)s exhibited inherent viscosities in the range of 0.35-0.71 dL/g. All of the poly(o-hydroxy amide)s were amorphous and soluble in many organic polar solvents, and most of them could afford flexible and tough films by solvent casting. The poly(o-hydroxy amide)s exhibited glass-transition temperatures (T g 's) in the range of 141-169°C and could be thermally converted into the corresponding polybenzoxazoles approximately in the region of 240 -350°C, as indicated by the DSC thermograms.Flexible and tough films of polybenzoxazoles could be obtained by thermal cyclodehydration of the poly(o-hydroxy amide) films. All the polybenzoxazoles were amorphous and showed an enhanced T g but a dramatically decreased solubility as compared with their poly(o-hydroxy amide) precursors. They exhibited T g 's of 215-272°C by DSC and showed insignificant weight loss before 500°C in nitrogen or air.

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

No abstract

No abstract