A series of environmentally friendly waterborne poly(urethane acrylate) (WPUA)/silica (SiO2) hybrids were synthesized by a sol-gel process on the basis of isophorone diisocyanate, polyester polyol (GE-210), dimethylpropionic acid, butyl acrylate and methyl methacrylate monomers, tetraethoxysilane (TEOS), and 3-glycidyloxy-propyl trimethoxysilane (GLYMO) as a coupling agent. The mechanical properties of the WPUA/SiO2 hybrids were investigated through tensile and hardness tests. Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and X-ray diffraction were used to assess the fracture surface morphology and the dispersions of the WPUA/SiO2 hybrids. The strength and hardness values of the WPUA/SiO2 hybrids were improved significantly. This was attributed to the synergistic effect of WPUA, GLYMO, and TEOS. The results show that SiO2 particles of the membranes had a uniform dispersion and formed an excellent interfacial bonding layer on their surfaces. The prepared hybrids showed good thermal stability and mechanical properties in comparison with pure WPUA and showed tunable transparence with the SiO2 fraction in the film. Through suitable adjustment of the TEOS content, some thin hybrids have potential applications as specialty materials. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1683-1695, 2011