γ-Ray Curing of Poly(methylsilane) and Poly(methylsilane−dimethylsilane) for Improved Ceramic Yields

Poly(methylsilane) (PMS) and poly(methylsilane−dimethylsilane) copolymers (P(MS−DMS)) were synthesized by Wurtz type polycondensation reactions of methyldichlorosilane or methyldichlorosilane−dimethyldichlorosilane mixtures in toluene. The obtained polymers were sealed in Pyrex tubes under vacuum and cured with γ-rays. Hydrogen, methane, and silane gases formed in the tubes were analyzed by GC-MS spectroscopy. IR, UV, and NMR spectra of the cured precursor suggest the formation of Si−Si cross-links with small amounts of Si−CH 2 −Si bridges during irradiation. Ceramic yields of the cured polymers increased as the irradiation dose increased. The pyrolysis of the precursor polymers at 1473 K yielded amorphous products with an almost stoichiometric composition. The precise C/Si ratio in the pyrolysis product depended on the starting polymer composition and the curing conditions.