The free radical emulsion polymerization of chloroprene (CP) is carried out at 9°C using different amounts of iodoform as the chain transfer agent. The molecular weight of polychloroprene (PCP) can be regulated effectively by CHI3. PCP suitable for use as an adhesive is obtained with 0.22–0.28 wt % CHI3 and reaches even higher monomer conversion than when mercaptan is used as the chain transfer agent. The emulsion polymerization of CP with high amounts of CHI3 (1.0–3.0 wt %) proceeds in a living polymerization manner. The molecular weight increases in proportion to the monomer conversion in the range of the whole polymerization process even up to very high monomer conversion. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The emulsion polymerization of styrene with three different chain transfer agents (CTAs) based on irreversible addition-fragmentation chain transfer (AFCT) mechanism was first reported in this work. The influences of these irreversible AFCT agents on the rate of polymerization, particle size, and molecular weight were investigated. It was found that the intrinsic activity and desorption behaviors of the CTAs determined the efficiency for molecular weight control, rate of polymerization, and particle size in the emulsion polymerization. It has been demonstrated that the rate of polymerization and particle size decreased dramatically in the presence of the irreversible AFCT agents with high chain transfer constant (ethyl α-ptoluenesulfonyl-methacrylate), meanwhile, the molecular weight of the polystyrene could not be controlled well, whereas the irreversible AFCT agents with low chain transfer constant (butyl(2-phenylallyl)sulfane and 2,3-dichloropropene) had a slight effect on the polymerization rate, particle size, and were fairly well for molecular weight control over the whole conversion range in the emulsion polymerization of styrene. The average number of radicals per particle and the number-average molecular weight were calculated by classical radical emulsion polymerization theory, and the experimental results were in good agreement with the results of model calculations, when the irreversible AFCT agents were used as CTAs. The effect of chain transfer agents on the kinetics and nucleation in the emulsion polymerization of styrene can be attributed to desorption of chain-transferred radicals from the polymer particles.The results of this work show that butyl(2-phenylallyl)sulfane as CTA in emulsion polymerization of styrene provides the best balance between the rate of polymerization and the efficiency for molecular weight control conflicting tendencies.

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A novel multidentate amine grafted on silica gel and magnetic microsphere was prepared. Its chemical structure was confirmed by C 13 NMR, XPS and FTIR, and the nitrogen content was determined by elemental analysis. It was also used as a ligand for CuCl and successfully catalyzed the atom transfer radical addition of both carbon tetrachloride (CCl 4 ) to methyl methacrylate and methyl trichloroacetate to styrene, repeatedly. The conversion and purity of the product were determined through gas chromatography and 1 H NMR, respectively. The immobilized copper catalyst complex was also used in atom transfer radical polymerization of styrene initiated by 1,1,1,3-tetrachloro-3-phenylpropane and methyl methacrylate initiated by methyl 2-methyl-2,4,4,4-tetrachlorobutyrate, respectively. Although the polymerization took place successfully, it did not proceed in a controlled fashion.

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