Silicone secondary cross-linked IPN based on poly(vinylacetate-co-hydroxyethyl methacrylate) and SiO2

Silicone secondary cross-linked interpenetrating polymer networks (IPNs) of poly(vinylacetate-co-hydroxyethyl methacrylate) (PVAc-HEMA) and SiO2 were prepared by free radical polymerization and condensation methods. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy (FTIR). Thermal properties of the copolymers were studied by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology of copolymers was also investigated by optical microscopy (OM) and then the effects of silicone concentrations, the reflux time, and composition on the phase morphology of the IPNs of PVAc-HEMA/SiO2 were discussed. The broadening of the transition region was observed with the increase of the prolongation of the reflux time and the tendency of the aggregation of silicon in the surface was also observed with Teflon as a substrate plate. However, an optically transparent film was easily achieved at higher temperature due to the chemical cross-link and physical entanglement between the two phases of PVAc-HEMA and SiO2.