An original route to poly[silylene-co-(2,4-disilapentane-2,4-diyl)] oligomers, efficient precursors of silicon carbide-based ceramics with variable C/Si ratios

Novel oligomers possessing a backbone formed of ((TRIPLE BOND)Si(SINGLE BOND)CH2(SINGLE BOND)Si(TRIPLE BOND)) and (SINGLE BOND)Si(SINGLE BOND)n units were prepared by the copolycondensation of bis(chlorosilyl)methanes and various dichlorosilanes in the presence of sodium, in refluxing toluene. The effect of the respective molar ratios of comonomers on the yields and the structure of the copolymers was investigated. The role of substituents on silicon atoms in the ability of these materials to provide convenient ceramic precursors upon pyrolysis was examined. When (TRIPLE BOND)Si(SINGLE BOND)H bonds were present, thermal cross-linking was readily performed and ceramics possessing variable C/Si ratios were prepared.