Phase-separation prevention and performance improvement of poly(vinyl acetate)/TEOS hybrid using modified sol-gel process

The formation of covalent bonds between silanols in copolymer and those in silica prevents organic-inorganic phase separation. Two series of hybrid co mposite materials, poly(vinyl acetate-co-vinyl trimethoxysilane)/TEOS and p oly[vinyl acetateco-3-(trimethoxysilyl)propyl methacrylate]/TEOS, were fabr icated using a modified sol-gel process. The hybrids were transparent. Two kinds of silane coupling agents, vinyl trimethoxysilane (VTS) and 3-(trimet hoxysilyl)propyl methacrylate (gamma -MPS), were used to prevent macrophase separation through formation of covalent bonds. Thermal analysis showed th at gamma -MPS was more effective than VTS for the formation of covalent bon ds. Enhancement of thermal stability of the hybrids was investigated by the rmogravimetric analysis. Photomicrographs of scanning electron microscopy a nd images of atomic force microscopy indicated that inorganic silica partic les were homogeneously dispersed in less than 50 nm in organic matrix. The morphological properties of hybrids were strongly dependent on the organic- inorganic composition. (C) 2001 John Wiley & Sons, Inc.