Synthesis, characterization, and pyrolytic conversion of a novel liquid polycarbosilane

Yunhui Fang, Muhe Huang, Zhaoju Yu, Haiping Xia, Lifu Chen, Ying Zhang, Litong Zhang

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

Partially ethynyl-substituted ethynylhydridopolycarbosilane (EHPCS) is prepared by Grignard coupling of chloromethyltrichlorosilane, chloromethylmethyldichlorosilane, and ethynylmagnesium bromide, followed by reduction with lithium aluminum hydride. The as-synthesized EHPCS, with a hyperbranched structure and an approximate formula of [SiH 1.35(CH3)0.37(C≡CH)0.28CH 2]n, has been characterized by GPC, FT-IR, and 1H, 13C, and 29Si NMR. The EHPCS can be cured readily in an inert atmosphere at 140°C for 6 h. Pyrolysis behavior and structure evolution of the cured EHPCS were studied by means of thermal gravimetric analysis-differential scanning calormetry, FT-IR, X-ray diffraction, and elemental analysis. It is suggested that hydrosilylation, ethynyl group polymerization, dehydrocoupling, and demethanation are involved in the cross-linking of EHPCS. The polymer-ceramic conversion is complete at 900°C, and it gives a stoichiometric and amorphous silicon carbide (SiC) with a yield of 78%. Further heating at 1200°C induces partial crystallization, forming locally ordered SiC4. The characteristic peaks of β-SiC are observable above 1600°C.

Original languageEnglish
Pages (from-to)3298-3302
Number of pages5
JournalJournal of the American Ceramic Society
Volume91
Issue number10
DOIs
StatePublished - Oct 2008
Externally publishedYes

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