Syntheses, Structures and Properties of Polycarbosilanes Formed Directly by Polymerization of Alkenylsilanes

Autor: Frances I. Hurwitz, Xin Y. Bu, Paula J. Heimann, Kassahun Beyene, Terrence A. Kacik, A. Harry Andrist, John Masnovi
Rok vydání: 1992
Předmět:
Zdroj: MRS Proceedings. 271
ISSN: 1946-4274
0272-9172
DOI: 10.1557/proc-271-771
Popis: Vinylsilane polymerizes to form predominantly a carbosilane polymer using dimethyltitanocene catalyst. This is in contrast to alkylsilanes, which afford polysilanes under the same conditions. The mechanism of polymerization of alkenylsilanes has been shown to be fundamentally different from that for the polymerization of alkylsilanes. The silyl substituent apparently activates a double bond to participate in a number of polymerization processes in this system, particularly hydrosilation. Isotopie labeling indicates the involvement of silametallocyclic intermediates, accompanied by extensive nuclear rearrangement. Polymers and copolymers derived from alkenylsilanes have relatively high char yields even for conditions which afford low molecular weight distributions. Formation of crystalline β-SiC is optimum for a copolymer of an alkylsilane and an alkenylsilane having a silane/carbosilane backbone ratio of 85/15 and a C/Si ratio of 1.3/1.
Databáze: OpenAIRE
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