Hybrid organic-inorganic polymer networks based on the copolymerization of methacryloxypropyl-silsesquioxanes and styrene

Silsesquioxanes synthesized by the condensation of (3-methacryloxypropyl)trimethoxysilane with concentrated formic acid, were copolymerized with styrene using benzoyl peroxide as initiator. When the ratio of styrene (S) to methacrylic (M) unsaturations was S/M > 1, the reaction attained an almost complete conversion as shown by the total reaction heat determined by differential scanning calorimetry. Several properties of the resulting hybrid organic-inorganic polymer networks were determined as a function of the silsesquioxane amount used in the formulation. Increasing the silsesquioxane fraction led to an increase of the glass transition temperature up to a point where devitrification was not observed prior to decomposition, an increase of the elastic modulus in the rubbery state, a decrease of the intensity of tan delta, and an increase of both Barcol hardness and thermal stability.