A new method for preparation of polystyrene nanoparticles by using a method of RAFT living polymerization was studied.Firstly,small molecular reversible addition⁃fragmentation chain transfer agent,three thiocarbonate (DBTTC),was synthesized for active polymerization.Then the emulsifier free emulsion polymerization method was used to prepare styrene polystyrene latex with narrow particle size distribution using itaconic acid as the monomer and ammonium persulfate as initiator.Effects of the molar ratio of St/IA,molar ratio of acetone/water,reaction temperature and amount of DBTTC on the latex particle size were studied respectively.The latices were characterized by Malvern nanosizer,TEM,GPC,surface tension and conductometric titration.The results show that when the temperature is 78 ℃,the molar ratio of St/IA is 10,and the molar ratio of DBTTC/St is 0.064,the molar ratio of acetone/water is 4∶6,the polystyrene nanometer latex particles with average particle size of 98 nm can be obtained.

Using a mixture of water and ethanol as medium, acrylamide (AM) as monomer, polymethylacrylic acid trithiocarbonates (PMAA-TTC) as chain transfer agent and AIBA as initiator, the polyacrylamide (PAM) was synthesized by dispersion polymerization. The effect of reaction media, monomer, initiator, reaction temperature and solid content on polymerization were investigated. The optimum reaction conditions were that the mass ratio of ethanol and water was 7∶3, the molar ratio of AM/Macro-CTA/AIBA was 6 000∶5∶1, the temperature was 50 ℃and the solid content was 10%.