Acrylic polymer/silica organic-inorganic hybrid emulsions were synthesized by a simple method, that is, a conventional emulsion polymerization and subsequent sol-gel process, to provide water-based coating materials. The acrylic polymer emulsions contained a silane coupling agent monomer, such as methacryloxypropyl-triethoxysilane, to form highly solvent-resistant hybrid films. On the other hand, the hybrid films from the surface-modified polymer emulsions, in which the silane coupling agent was located only on the surface of the polymer particles and the particle core was not crosslinked, did not exhibit high solvent resistance. A honeycomblike array structure, which was derived from the polymer particles (diameter approximate to 50 nm) and the silica domain, on the hybrid film surfaces was observed by atomic force microscopy. The crosslinked core part and silane coupling agent containing the shell part of the polymer particles played important roles in attaining high solvent resistance. (c) 2006 Wiley Periodicals, Inc.