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

✍ Scribed by Sheng-Huei Hsiao; Liang-Ru Dai; Ming-Hsiang He

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 246 KB
• Volume: 37
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(19990415)37:8<1169::aid-pola13>3.0.co;2-x

✦ Synopsis

4,4Ј-(1,4-Phenylenedioxy)dibenzoic acid as well as the 2-methyl-, 2-tertbutyl-, 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 T g s in the range of 167-237°C and could be thermally cyclodehydrated into the corresponding poly(1,3,4-oxadiazole)s and poly(amide-1,3,4oxadiazole)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 T g s in the range of 208 -243°C and did not show significant weight loss before 450°C either in nitrogen or in air.