This work prepared the highly transparent photo-curable co-polyacrylate /silica nanocomposites by using sol-gel process. The FTIR and C-13 NMR analyses indicated that during the sol-gel process, the hybrid precursors transform into composites containing nanometer-scale silica particles and crosslinked esters/ anhydrides. Transmission electron microscopy (TEM) revealed that the silica particles within the average size of 11.5 nm uniformly distributed in the nanocomposite specimen containing about 10 wt% of Si. The nanocomposite specimens exhibited satisfactory thermal stability that they had 5% weight loss decomposition temperatures higher than 150 degrees C and coefficient of thermal expansion (CTE) less than 35 ppm/degrees C. Analysis via derivative thermogravimetry (DTG) indicated that the crosslinked esters /anhydrides might influence the thermal stability of nanocomposite samples. The UV-visible spectroscopy indicated that the nanocomposite resins possess transmittance higher than 80% in visible light region. Permeability test revealed a higher moisture permeation resistance for nanocomposite samples, which indicated that the implantation of nano-scale silica particles in polymer matrix forms effective barrier to moisture penetration. Adhesion test of nanocomposite samples on glass substrate showed at least twofold improvement of adhesion strength compared with oligomer. This evidenced that the silica and the hydrophilic segments in nanocomposite resins might form interchains hydrogen bonds with the -OH groups on the surface of glass so the substantial enhancement of adhesion strength could be achieved. (c) 2007 Wiley Periodicals, fnc.