Pyrolysis—gas chromatography—mass spectrometry of poly(dialkylsilylenes)

Abstract

A series of silylene copolymers with di- n-alkyl substituent groups varying from dimethyl to di- n-hexyl were pyrolysed in an analytical pyrolyser coupled to a capillary GC—MS system. The thermal decomposition of the silylene copolymers begins at about 200°C and proceeds via cyclic oligomer formation. The pyrolysis at 300°C of those copolymers which contain dimethylsilylene units lead to tetracycles and pentacycles, but those which have ethyl or longer alkyl substituents decompose exclusively to tetracycles. The copolymer composition and structure were evaluated from the pyrolysis product distribution data. Mass spectra and GC retention indices were obtained on several di- n-alkylsilylene cyclotetramers and cyclopentamers.