Thermal weight loss of silica-poly(vinyl acetate) (PVAc) sol-gel composites

Thermogravimetric analyses of sol-gel derived silica and silica-poly(vinyl acetate) (PVAc) materials show that the loss in weight between 35 and 900°C can be attributed to three distinct reactions. Samples were prepared by dissolving the reactants tetraethyl orthosilicate (TEOS), poly(vinyl acetate) (PVAc), and water in mixtures of ethanol and formamide. The lowest temperature weight loss is due to the decomposition/removal of the solvents, while the intermediate weight loss corresponds to decomposition of the PVAc. The highest temperature weight loss is related to the dehydroxylation of the silica surface. The relative amounts of ethanol and formamide have a considerable effect on processing time, drying behavior, and the resulting thermal behavior of the gels.The financial support of the Center for Ceramic Research, a New Jersey Commission on Science and Technology Center, is greatly appreciated.