Preparation of low density TiO2/poly (methyl methacrylate) composite particles by emulsifier-free emulsion polymerization

► Low density TiO2/PMMA composite particles were prepared by polymerization. ► The polymerization is emulsifier-free emulsion polymerization in water. ► The composite particles were characterized by FTIR, FESEM, TEM, TGA and DLS. ► Composite particles density was evaluated by a facile floating-sinking method.