| Cumyl Dithiobenzoate (CDB), 1-Phenylethyl Dithiobenzoate (PEDB)and Benzyl Dithiobenzoate (BDB),there RAFT agents,were synthesized and the structures of the products were determined by IR spectrum and 1H-NMR spectrum .The bulk polymerization of styrene using AIBN as initiator at the presence of a RAFT agent was studied in detail, including the kinetics and control over molecular weight and molecular weight distribution. The results confirmed the distinct living polymerization character of the reaction system and showed that among the three obtained RAFT agents BDB was the best for styrene bulk polymerization system. A mathematic model for the kinetics of the styrene RAFT bulk polymerization was set up and modification to the model of molecular weight reported in literatures was made.On the basis of the above bulk polymerization, further study on emulsifier-free emulsion polymerization of styrene with the presence of RAFT was made. Firstly, the RAFT BDB was used for preparation of styrene-acrylic acid RAFT oligomer by bulk polymerization,which has function a self emulsification. The so prepared RAFT copolymer was then employed in followed study on emulsion polymerization of styrene without using any extra surfactant. Polymer Emulsion products of good stability were obtained by this access.According to the experiment work, for the preparation of stable soap-free polymer emulsion, triethylamine is needed to neutralized 80~100% of the acylic acid used. The use of acetone is benifitial to the emulsification of the oligomer. At temperature of 75°C, the reaction could proceed faster and thus led to a stable product. The molecular weight of the polymer product showed a linear relationship with the monomer conversion. And the real molecular weight was higher than the theoretical calculation. With a higher monomer conversion, the molecular weight distribution became broader. In the work, the higher ratio...
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