Titanium dioxide core and polymer shell composite poly(methyl methacrylate-co-n-butyl acrylate-co-methacrylic acid) [P(MMA-BA-MAA)] particles were prepared by emulsion copolymerization. The stability of dispersions of TiO2 particles in aqueous solution was investigated. The addition of an ionic surfactant, sodium lauryl sulfate, which can be absorbed strongly at the TiO2/aqueous interface, increases the stability of the TiO2 dispersion effectively by increasing the absolute value of the potential of the TiO2 particles. The adsorption of the nonionic surfactant, Triton X-100, on the surface of TiO2 particles is less than that of the ionic surfactant. Fourier transform IR spectroscopy was used to measure the content of MAA composite particles. Dynamic light scattering characterized the composite particle size and size distribution. The field-emission scanning electron microscopy results for the composite particles showed a regular spherical shape, and no bare TiO2 was detected on the entire surface of the samples. The composite particles that were produced showed good spectral reflectance compared to bare TiO2. Thermogravimetric analysis results indicated the encapsulated TiO2 and estimated density of composite particles. There was up to 78.9% encapsulated TiO2 and the density ranged from 1.76 to 1.94 g/cm(3). The estimated density of the composite particles is suitable at 1.73 g/cm(3), which is due to density matching with the suspending fluid. The sedimentation experiment indicates that reducing the density mismatch between the composite particles and suspending fluid may enhance the stability. © 2005 Wiley Periodicals, Inc.