Siloxane bond formation by heterofunctional condensation of alkoxysilane and halogenosilane. Application to the preparation of copoly(tetramethyl- p-silphenylenesiloxane-dimethylsiloxane)

Abstract

Siloxane linkages are formed non-hydrolytically by the reaction of dihalogenosilanes with either dibenzylether, or dibenzyloxysilanes and dibenzhydryloxysilanes. The heterocondensation reaction is activated in the presence of NaI (in acetonitrile) or fluoride anions. This offers an alternative copolymerization route to the usual dehydrocondensation of SiOH-terminated species. Thus, the title copolymer was prepared by reaction of equimolar amounts of Me 2Si(OCHPh 2) 2 and 1,4-bis(chlorodimethylsilyl)benzene at 100°C. The 29Si NMR spectrum supports a quasi-random sequence in the copolymer. Thermal stability is similar to that reported for an alternating microstructure, as inferred from thermogravimetric analysis.