Platinum Metals Rev., 2000, 44, (4), 172
Polysiloxanes are polymers with an alternating chain of silicon and oxygen atoms. Polysiloxanes have a range of very valuable properties which are utilised commercially: inertness, resistances to water and oxidation, and high thermal stabilities. However, little work has been done to develop dehydrocoupling polymerisation to give polysiloxanes. A team of scientists at the University of Cincinnati have now developed a general method of dehydrocoupling polymerisation to give alternating copolymers of silphenylenesiloxanes from bis-silanes and disilanols, under mild conditions, using Wilkinson’s catalyst, RhCl(Ph3P)3, (R. Zhang, J. E. Mark and A. R. Pinhas, Macmmolecules, 2000, 33, (10), 3508–3510).
Silphenylenesilane polymers with controllable microstructures and average molecular weight of 10,100 g mol−1 were produced. The best polymerisation occurred between p -bis(dimethylsiryl)benzene and p -bis(dimethylhydroxysilyl)benzene. Among other alternating copolymers produced were poly-(tetramethyl-p -silphenylenesiloxane) (poly-TMPS) and a combination of tetramethyl-m -silphenylenesiloxane and TMPS. The rhodium catalyst was very efficient and robust under the reaction conditions.