Crack- and Shrinkage-Free Ethylene-Bridged Polysilsesquioxane Film Prepared by a Hydrosilylation Reaction.With the aim of developing an improved strategy for the preparation of ethylene-bridged polysilsesquioxanes as thermal insulator materials, this paper describes the synthesis of a crack- and shrinkage-free ethylene-bridged polysilsesquioxane film by the hydrosilylation reaction of hydrodimethyl-silylated oligomethylsilsesquioxane (MSQ-SiH) and dimethylvinyl-silylated oligomethylsilsesquioxane (MSQ-SiVi) in the presence of Karstedt's catalyst.  The obtained ethylene-bridged polysilsesquioxane film showed lower density and thermal diffusivity (1.13 g/cm3 and 1.15 × 10-7 m2/s, respectively) than a polymethylsilsesquioxane film (1.34 g/cm3 and 1.36 × 10-7 m2/s, respectively).  As a result of the introduction of the SiCCSi ethylene bridge, the thermal insulation property of the polysilsesquioxane film was enhanced.
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