A FAST CONVENIENT METHOD TO PREPARE HYBRID SOL-GEL MATERIALS WITH LOWVOLUME-SHRINKAGES

We present a simple and fast method for the synthesis of polyacrylates -silica hybrid materials with significantly low volume shrinkages thro ugh the sol-gel reactions of tetraethyl orthosilicate and 2-hydroxyeth yl methacrylate along with the free-radical polymerization of the acry late monomer. The volume shrinkage from the processible sol to the fin al product was about 6-20% for the hybrid materials having the silica contents up to about 50 wt-%. As a result of the low shrinkage, crack- free, transparent and monolithic hybrid materials of relatively large sizes can be prepared within a short period of 6 to 12 hours. The form ation of covalent bonding between the organic and the silica component s in the hybrid materials was demonstrated. Thermal stability of the p olyacrylate component in the hybrid materials were found to be higher than that of the bulk polymer. Other vinyl polymers such as poly(methy l methacrylate) and polyacrylonitrile have also been incorporated into the inorganic silica sol-gel matrix by using this method.