Microstructural and morphological characteristics of PS-SiO2 nanocomposites

A series of organic-inorganic hybrid materials have been prepared by copoly merizing styrene and alkoxysilane-methacrylate via the sol-gel process. The alkoxysilane-containing copolymer precursors were synthesized by free-radi cal copolymerization of styrene with an alkoxysilane-containing monomer, me thacrylic acid 3-(trimethoxysilyl)propyl ester (MAMSE), at several feeds. T he copolymer precursors were then hydrolyzed and condensed to generate PS-S iO2 hybrid sol-gel materials. The hybrid copolymers possess excellent optic al transparency and a nanoscale microphase separation. The copolymer precur sors and their hybrid copolymers were characterized by FT-IR spectra, H-1 N MR spectra, DSC, and TGA thermograms. Chemical structural effect on the mor phology and thermal properties was investigated with SEM, mapping photograp hs, and high-resolution solid state C-13 and Si-29 NMR spectra. It was foun d that compatibility between copolymer and silica mainly comes from incorpo rating the polymer with silica covalently. Moreover, MAMSE could be hydroly zed to methacrylic acid and ester-interchanged to silyl methacrylate during heat treatment. This also enhances the compatibility between the copolymer and silica, The thermal properties of the PS-SiO2 hybrid copolymers are im proved as silica content increase. However, the presence of silyl ester gro ups, which were formed during heat treatment, would reduce the thermal stab ility of the hybrid copolymers. (C) 2000 Elsevier Science Ltd. All rights r eserved.