Novel diacetylinic aryloxysilane polymers: A new thermally cross-linkable high temperature polymer system

Abstract

A new diacetylinic polymer was prepared through polycondensation of 4,4′-buta-1,3-diyne-1,4-diyldiphenol and dichlorodiphenylsilane. This aromatically substituted siloxane polymer contained thermally cross-linkable diacetylene links in the mainchain. FTIR, Raman, and 13C NMR analysis confirmed the diethynyl group was present in the polymer. DSC analysis showed the polymer had a Tg of 130 C, and a strong exothermic cure peak at 260 C. Parallel plate rheological testing through monitoring of changes in viscosity confirmed the polymer cross-linked during heating. After curing above 260 C, the polymer vitrified, with no detectable Tg observed on subsequent reheating. The activation energy of thermally initiated curing of the diacetylene groups was estimated to be 120 ± 17 kJ/mol from DSC data using the Ozawa Flynn Wall method. TGA analysis in nitrogen starting from uncured polymer showed a 5% weight loss temperature of 541 C and a pyrolysis yield of 82% at 800 C. © 2013 American Chemical Society.