Synthesis of polycarbonate-silica nanocomposites from copolymerizationof CO2 with allyl glycidyl ether, cyclohexene oxide, and sol-gel

The copolymerization of carbon dioxide, allyl glycidyl ether, and cyclohexene oxide catalyzed by the system consisting of Y(CF3CO2)(3) Zn(Et)(2), and pyrogallol in the solvent of 1, 3-dioxolane was performed in this study. The IR, H-1 NMR, and C-13-NMR spectra, as well as the elemental analysis, indicated that the resulting copolymer was an alternating polycarbonate possessing more than 90% of carbonate units. The molecular weight could be as high as 1.5 X 10(5), and the polydispersity index was 4.5. The resultant polycarbonate was found to effectively react with 3-(trimethoxysilyl)propyl methacrylate via a free radical reaction to result in a precursor used in the sol-gel process to synthesize a polycarbonate-silica nanocomposite. The nanocomposites were characterized by SEM, Si-29 NMR, TGA, DSC, and UV-Vis. Silica particles with size less than 100 nm were found to disperse uniformly in the nanocomposites. It was also found that the thermal properties were dependent on the content of cyclohexene carbonate units. Both the thermal and mechanical properties of the resultant nanocomposites could be adjusted with silica content, while the transparency was comparable to the base copolymer even at high silica contents. (c) 2005 Wiley Periodicals, Inc.