The monodispersed anionic polystyrene (PS) microspheres were synthesized via emulsifier-free emulsion polymerization with polystyrene (PS) and acrylic acid (AA) as monomers. The effect on PS microspheres structure and monodispersity was discussed. The results indicate that the copolymer has been prepared and AA comonomer makes the size of PS particles decrease and endow the particle surface electronegative. It is also observed that the polymerization activation energy is 42. 95kJ/mol and the reaction rate increases with the polymerization temperature raising. With the increasing of KPS amount

the particle size also decreases and exhibits the optimum monodispersity when the amount of KPS reaches 0. 6%. Additionally

with the increase of acetone amount

the solubility of polymer increases which induce the particle size to decrease and the size distribution to become broader.