PREPARATION OF SOLUBLE POLYCARBOSILANE POLYMERS USING GROUP-4 METALLOCENE CATALYSTS

The preparation of a series of carbosilane monomers of the form H3Si-R -SiH3 (primary carbosilane) and H(2)PhSi-R'-SiPhH(2) (secondary carbos ilane) (R = -CH2CH2-, --CH(2)CH(2)SiPh(2)CH(2)CH(2)-, -CH(2)CH(2)CH(2) SiPh(2)CH(2)CH(2)CH(2)-; R' = (CH2)(n) (n = 1-3), -CH(2)CH(2)SiMe(2)CH (2)CH(2)-) is reported. Polymerization of the primary carbosilanes res ulted in the formation of insoluble polycarbosilanes in less than 1 h. The secondary carbosilanes, however, yielded polymers that were solub le in common solvents (e.g., CHCl3, C6H6, and THF). GPC analyses of th e polymers indicated molecular weights as high as 12 000. The molecula r weights were highly dependent on the structure of the monomer and th e reaction conditions (temperature, solvent, catalyst concentration, a nd catalyst nature).