Study of the process of formation of poly- p, p′-terephthaloyl-N-methyl hydrazide-1,3,4-oxadiazoles

• Published in: Polymer science USSR 1985, Vol.27 (6), p.1283-1290
• Main Authors: Korshak, V.V, Byerestneva, G.L, Bibileishvili, D.V, Petrovskii, P.V, Volokhina, A.V, Raskina, A.B
• Format: Article
• Language: English
• ISSN: 0032-3950; 1878-268X
• DOI: 10.1016/0032-3950(85)90268-0

The authors have studied the process of formation of macromolecules of poly- p, p′-terephthloyl-N-methyl hydrazide-1,3,4-oxadiazoles in conditions of high-temperature polycondensation in oleum. The investigation using 13C-{ 1H} NMR spectroscopy established that the process of formation of these copolymers is multistage and made up of the following stages: saponification of dimethylterephthalate, formation of oligo-1,3,4-oxadiazole with terminal reactive carboxyl and hydrazide groups, subsequent cyclocondensation ensuring the growth of the chains of the macromolecules, methylation of the 1,3,4-oxadiazole fragments of the macromolecules by methyl sulphuric acid forming as a result of saponification of dimethylterephthalate and opening of the 1,3,4-N-methyl oxadiazole cycle on extrusion of the polymer into aqueous sulphuric acid leading to the formation of N-methylhydrazide fragments in the chains of the macromolecules. Methods are worked out for the quantitative evaluation of the content of different types of units in the chains of the copolymers at different stages of formation of the polymer.