Syntheses of hyperbranched poly(carbosilarylenes)

New hyperbranched poly(carbosilarylenes) are described that exhibit low gla ss transition temperatures and high thermal stabilities. The incorporation of Si-O-Si linkages into the branches leads to a polymer of increased flexi bility but considerably lower thermal stability. The hyperbranched polymers are prepared via a one-pot hydrosilylation polymerization of aromatic AB(3 ) monomers. The monomers are prepared from commercially available reagents using lithium-halogen exchange reactions followed by treatment with chloros ilanes. The glass transition temperatures of the hyperbranched polymers ran ge from -45 degrees C for the siloxane-containing polymer to 12 degrees C f or the 1,4-substituted polymer. Number-average molecular weights (GPC) rang e from 2560 to 5600. The degree of branching in these polymers was determin ed by quantitative Si-29 NMR spectroscopy and found to be very close to the theoretical value of 0.44 for AB(3) systems.