Catalytic Synthesis of Polymethylsilsesquioxanes

摘要

Dimethyltitanocene can be used to promote the redistribution of -(MeHSiO)x(-)cyclomers and linear oligomers to produce a polymethylsilsesquioxane copolymer. A mechanism for this redistribution is suggested, that involves sigma-bond metathesis promoted by a Titanium(IV) species. The structural evolution of the polymethylsilsesquioxane copolymer as it is heated to 1000 deg C is followed using solid state (29 Silicon Nuclear Magnetic Resonance). Thermogravimetric Analysis experiments and chemical analysis support the NMR results which indicate that most of the starting monomer is either volatilized or undergoes further redistribution, so that by 400 deg C only polymethylsilsesquioxane remains. Keywords: Polymers, Catalysis, Synthesis, Silicon compounds, Hydrogen, Alcoholysis, Alkoxy derivates, Polysilazane oligomers, Ceramic materials, Polysiloxane, Cage structures. (JG)