Heterogeneously catalysed crosslinking of polycarbosilane with divinylbenzene

Crosslinking of polycarbosilane (PCS) with divinylbenzene (DVB) is readily accomplished using heterogeneous catalysis with platinum chloride in heptane to provide a silicon carbide precursor that produces a ceramic with significantly reduced oxygen content. The ceramic yield after crosslinking increased from 47% to between 72% and 78%; however, crosslinking may be influenced by dehydrogenative silylation of hydroxyl groups. Solid-state 13C NMR spectroscopy of the crosslinked PCS showed peaks assignable to the aromatic group at 144 and 126.7 ppm. Monitoring of the crosslinking reaction by 1H NMR spectroscopy indicated 40% consumption of the vinyl bonds of DVB within 10 min and complete consumption within 16 h. Infrared spectroscopy showed no increase in the peak at 3,650 cm−1 due to O–H stretching in Si–OH, demonstrating that hydrosilylation crosslinking is a highly effective non-oxidative crosslinking technique.