The catalyst system consisting of Y(CF3CO2)(3), Zn(Et)(2), and pyrogallol in the solvent of 1,3-dioxolane was found to be effective for the copolymerization of allyl glycidyl ether with carbon dioxide at 60 degreesC and 400 psi. The IR, H-1-NMR, and C-13-NMR spectra as well as the element analysis indicated that the resulting copolymer was an alternating polyethercarbonate with the carbonate content higher than 97.5%. The resulting polyethercarbonate could react with 3-(trimethoxysilyl)propyl methacrylate via a free radical reaction to generate the alkoxysilane-containing copolymer precursors that were used in the subsequent sol-gel process to result in the polyethercarbonate-silica nanocomposite. The generated nanocomposite was characterized by C-13-NMR, Si-29-NMR, SEM, DSC, TGA, ESCA, and UV-Vis. The mechanical properties were also measured. A good compatibility between polyethercarbonate and silica and a SiO2 network with silica particles less than 100 nm in the nanocomposite were observed. Both the thermal and mechanical properties of the resulting polyethercarbonate-silica nanocomposite were found to enhance with silica content. The optical transparency of the generated nanocomposite was comparable to that of the based polyethercarbonate. (C) 2004 Elsevier Ltd. All rights reserved.