Preparation and characterization of styrene/styryl-polyhedral oligomeric silsesquioxane hybrid copolymers

Background: Organic-inorganic nanocomposites were prepared by copolymerization of various monomers and polyhedral oligomeric silsesquioxane (POSS) derivatives. Preliminary results showed that styrene/styryl-POSS copolymers could be obtained using CpTiCl₃ catalyst. In the work reported here, the copolymerization of styrene and styryl-substituted POSS was studied in detail for a more effective catalyst, Cp*TiCl₃. Results: The glass transition temperature (T_g) of the copolymers prepared increased with increasing POSS content. The degradation temperature (T_d) of the copolymerswas 60°C higher than that of syndiotactic polystyrene under nitrogen. Although the thermal properties were improved by incorporation of POSS, the catalytic activity decreased with POSS content. The racemic triad and syndiotactic index of the copolymers decreased with increasing POSS content. Gel permeation chromatograms of the copolymers exhibited multimodal distribution due to the presence of multi-active centres, which were formed by interaction of Ti with the POSS siloxane linkage. Conclusion: With the incorporation of POSS, the thermal properties of polystyrene were improved. The styrene/styryl-POSS copolymers are formed through the various active sites arising from the interactions of Ti with POSS.