Waterborne raspberry—like PMMA／SiO2 composite microspheres were synthesized by a soapless one-step method in the presence of aqueous silica sols and cationic monomer 2-(methacryloyy)ethyhrimethylammonium chloride(MTC)．MTC was eopolymerized with MMA via radical polymerization and then nanosilica particles were deposited onto the surfaces PMMA particles in the aqueous medium thransh electrostatic interaction between negatively charged nanosiliea particles and positively charged MTC．The whole process neither required surface treatment for nanosiliea particles nor additional surfactant or stabilizer．TEM indicated that electrostatic interaction between silica and MTC was strong enough for the formation of long-stable nanocomposite microspheres with raspbetry-like morphology．The average particle sizes of the obtained composite microspheres ranged from 180—300 nm

depending on the precise formulation．Thermogravimetric analysis indicated silica content in the nanocomposite microspheres ranged from 16．4％～40．8％．Some influencing parameters such as initial silica amount and MTC amount on the diameter

silica contents and morphologies of the composite microspheres were investigated in detail.A possible formation mechanism of the raspberry—like composite microspheres was proposed．