Polystyrene/TiO2 nanocomposite particles were synthesized in high yield by in situ polymerizing styrene in the presence of 3-(trimethoxysilyl)propylmethacrylate (MPS) modified nano TiO2 in ethanol media. Polystyrene/TiO2 nanocomposite particles were characterized by means of FTIR spectroscopy, elemental analysis, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). FrIR investigation provided direct and clear evidence for the presence of polystyrene shell on nano TiO2 core particles, and TGA showed quantitative evidence of the presence of polystyrene shell on nano TiO2 core particles. It was demonstrated that polystyrene shell was chemically bonded to nano TiO2 core surface with a high coating efficiency. (c) 2004 Elsevier B.V. All rights reserved.