Synthesis, characterization and thermal properties of SiH and SiOH terminated hybrid polysiloxanes

Abstract

Silalkylene polysiloxanes, also called 'hybrid' polysiloxanes, are polysiloxanes including an alkyl spacer between two silicon atoms. So far, several studies had been performed on hybrid polysiloxanes with perfluoroalkyl spacers. The present study focuses on hybrid polysiloxanes with alkyl spacers -C n H 2n -(called SiOHT PSX). Their synthesis is described, and the influence of the size of the spacer on the thermal behavior of these SrOHT PSX has been evaluated. The synthesis of SiH terminated hybrid oligosiloxanes (SiHT PSX) with different sizes was performed via a new route: polyhydrosilylation of octadiene with tetramethyldisiloxane (TMDS). The theoretical control of the average number molecular weights (M n ) was achieved by adding an excess of one of the difunctional compounds (TMDS in this case). These M n are discussed and compared to the experimental M n determinted by 1 H NMR. The influence of the size of the SiHT PSX on its thermal behavior was studied and considered in parallel with the homologue SiOHT PSX. The SiOHT PSXs synthesized may be considered as choice elastomers once they exhibe a low glass transition temperature (T g ) and excellent thermal resistance. The SiHT PSXs exhibit lower T g but they show a lower thermal resistance. However, they may be used as performing precursors for the synthesis of block copolymers.