A new class of aromatic poly(1,3,4-oxadiazole)s and poly(amide-1,3,4-oxadiazole)s containing (naphthalenedioxy)diphenylene groups
Journal
Polymer Journal
Journal Volume
34
Journal Issue
12
Pages
917-924
Date Issued
2002
Author(s)
Hsiao, S.-H.
Abstract
Polyhydrazides and poly(amide-hydrazide)s having inherent viscosities of 0.31-1.17 dL g-1 were prepared from two ether-naphthalene-dicarboxylic acids, 4,4′-(1,5-naphthalenedioxy)dibenzoic acid (1,5-NDA) and 4,4′-(2,3-naphthalenedioxy)dibenzoic acid (2,3-NDA) with terephthalic dihydrazide, isophthalic dihydrazide, and p-aminobenzhydrazide via the phosphorylation polycondensation reaction. Except for one example, the hydrazide polymers were essentially amorphous and readily soluble in polar organic solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc). They could be cast into transparent, flexible, and tough films with good mechanical strengths from solution in DMAc. These hydrazide polymers exhibited glass-transition temperatures (Tgs) in the range 179-190°C and could be thermally cyclodehydrated into the corresponding poly(1,3,4-oxadiazole)s and poly(amide-1,3,4-oxadiazole)s in the solid state at elevated temperatures. The oxadiazole polymers had Tgs of 228-242°C (by differential scanning calorimetry) and 10% weight loss temperatures above 500°C, as revealed by thermogravimetric analysis in nitrogen or in air.
Type
journal article