Kinetics study of living microemulsion polymerization mediated by reversible addition-fragmentation chain transfer

Reversible addition-fragmentation chain transfer (RAFT) polymerization is usually carried out in emulsion or miniemulsion, often encounters problems of rate retardation, phase separation, and loss of activity in these systems. Compared with emulsion or miniemulsion, microemulsion remains stable during polymerization because of presence of large amount surfactant that promotes formation of large number of monomer swollen micelles. Therefore, microemulsion typically shows fast polymerization rate and produces latex nanoparticles composed of high molecular weights polymers. Until now, only few RAFT polymerizations have been successfully conducted in microemulsion and related kinetics studies are very limited. Here, kinetics studies on RAFT microemulsion polymerization were carried out and the factors that affected kinetics were detailedly investigated. Kinetic parameters, theoretical molecular weights, chain transfer constant, propagate rate constant, half reaction time and polymerization rate constant were all calculated. Experimental results indicated temperature and concentration of chain transfer agent were important factors which influenced polymerization kinetics. In addition, the chemical structure of chain transfer agent, molecular weights and its distribution, and the morphologies structure of polymers were characterized by ¹H NMR, FT-IR, GPC and TEM, respectively.