Electroreductive Synthesis and Characterization of Polycarbosilanes Containing Oligosilane Units

Abstract

Electroreductive copolymerization of 1,4‐bis(chloromethylphenylsilyl)benzene with dichlorodimethylsilane was carried out under constant current conditions, using Mg electrodes, to give the corresponding copolymers having (disilanylene)phenylenes and dimethylsilylene units in 40–71% yield. The resulting copolymers having dimethylsilylene units showed solubility in common organic solvents. The (disilanylene)phenylene units were predominantly included in the resulting copolymers. The molecular weight determined by gel permeation chromatography (GPC) was 1740–2900 depending on the units composition, and all elution profiles showed broad monomodal molecular weight distributions. The copolymers showed characteristic strong UV absorption bands (λmax) at 250 nm. Extinction coefficients (ϵmax) per (disilanylene)phenylene or silylene units were calculated to be 12,340–13,750, and their extinction coefficients increased with an increase of (disilanylene)phenylene units. The temperatures of 10% wt loss of the copolymers were observed at 380–395°C and the weight loss at 500°C was 33.0–34.3%. The thermal properties of the copolymers were found to depend on their molecular weights and the content of (disilanylene)phenylene units.