Chain mobility in bulky carbosilane modified polymeric siloxane systems

Abstract

Hydrosilylation of bulky carbosilanes [CH2=CHRC(SiMe 2R')3, R=CH2, (CH2)3 or SiMe2; R'=Me or Ph] with oligosiloxane precursors [M(D 2DH)7D2M, M(D2D 2H)11D2M, PDMSx%- PMHS100-x% (x=85, 50, 30, 0)] was carried out. The relationship between the mobility of siloxane chain and the type of carbosilane moiety, as well as the type of distribution of carbosilane group along the polymer chain, was consecutively studied. Carbosilane substituents, due to their exceptional steric requirements, have been shown to strongly affect thermal properties of siloxane oligomers, implying a substantial change of the chain flexibility and free volume of modified oligomers.