Preceramic polysiloxane networks obtained by hydrosilylation of...

Precreamic polysiloxane networks were prepared by hydrosilylation of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (D(4)(Vi)) with a series of linear hydrogensiloxanes as well as with a cyclic hydrogensiloxane, namely 2,4,6,8-tetramethylcyclotetrasiloxane (D(4)(H)) at various hydrogensiloxane/D(4)(Vi) molar ratios in the starting reaction mixture. FTIR spectroscopic measurements conducted during the processes as well as for the reaction products allowed to reveal that the rate of D(4)(Vi) hydrosilylation as well as its efficiency are influenced by the type of hydrogensiloxane used and by the reactants molar ratio. Ceramic yields determined at 1000°C by thermogravimetric analyses were higher for D(4)(Vi)-D(4)(H) than for D(4)(Vi) - linear hydrogensiloxane networks (86-89% vs 65-76%, respectively). Preceramic polysiloxanes prepared as well as the products of their pyrolysis obtained after thermal investigations were monolithic, pore-less materials.