• density;
  • hydrosilylation;
  • hyperbranched polymer;
  • polycarbosilane;
  • refractive index;
  • thermal properties;
  • thin film


Polycarbosilanes were synthesized by hydrosilylation reaction of A2 monomer containing bis Si[BOND]H moieties and Bn (n = 2, 3, and 4) monomers containing di-, tri-, and tetra-vinyl groups in the presence of Karstedt's catalyst. The corresponding linear polycarbosilanes (LPC) and hyperbranched polycarbosilanes (HBPC) having Mn 2200–51,500 were obtained in 34–94% yield, without any gel product. The values of refractive index (nD) of the synthesized LPC and HBPC were in the range from 1.460 to 1.711, and were consistent with the structures of the synthesized products. In the case of HBPC, the values of nD increased with increase of number-average molecular weight (Mn), molecular weight distribution (Mw/Mn), and glass transition temperature (Tg), apparently because of increased density due to the presence of microgels, that is, high refractive index hyperbranched carbosilanes could be synthesized by A2 + Bn (n = 3 and 4) method. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010