Carborane polymers. I. Polyesters

Autor: Joseph Green, Murray S. Cohen, Nathan Mayes
Rok vydání: 1964
Předmět:
Zdroj: Journal of Polymer Science Part A: General Papers. 2:3113-3133
ISSN: 1542-6246
0449-2951
DOI: 10.1002/pol.1964.100020711
Popis: Polyesters containing a unique polycycloborane in the polymer structure have been prepared. The boron hydride moiety, C2B10H10, has been named carborane and approximates in size a sphere with an effective van der Waals radius of 4 A. Polyesters of 2000–3000 molecular weight were prepared by allowing carborane monomers to react with each other or with organic or fluorocarbon diols or diacids. A polyester of approximately 20,000 molecular weight was prepared and it was demonstrated that molecular weight obtainable was a function of monomer ratio and purity. It was demonstrated that polyesterification of adipic acid with a carborane diol was significantly slower than the analogous reaction with 1,4-butanediol. Reactions of carborane diols with carborane diacids were shown to occur with difficulty or not at all. Transesterification of carborane malonates also occurred with difficulty. The inhibitions of carborane materials toward polyesterification was attributed to both steric and polar influences with the former being more significant. The effect of the bulky carborane group in the polyester chain on the properties of the polymer was demonstrated by the preparation of polyadipates from 1,2-bis(hydroxymethyl)carborane, 1,4-butanediol, and 1,4-butynediol. The first product was a liquid which showed no tendency to crystallize. The noncarborane polyesters were crystalline waxes at equivalent chain length. The bulk of the carborane group apparently inhibited close packing and subsequent crystallization. A comparison of the carborane polyadipate and polysuccinate showed that the latter was a hard glass, apparently due to a decrease in chain flexibility.
Databáze: OpenAIRE
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