A magnetic poly(methyl methacrylate) (PMMA) composite latex was prepared by soapless emulsion polymerization in the presence of ferrofluid, and the ferrofluid was prepared by means of a coprecipitation method. The effects of various polymerization parameters, such as the monomer concentration, ferrofluid content, and initiator concentration, on the conversion curve and particle size of the magnetic composite latex particles were examined in detail. The results showed that two nucleation mechanisms were involved according to the polymerization conditions. In the monomer‐rich and less ferrofluid system, self‐nucleation of PMMA was dominant over the entire course of emulsion polymerization. In the ferrofluid‐rich system, seeded emulsion polymerization was the main course to form the magnetic composite latex particles. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5695–5705, 2004

Dodecylbenzenesulfonic acid, DDBSA, was chosen as a new rate‐accelerating additive for 2,2,6,6,‐teramethyl‐1‐piperidinyloxy (TEMPO)‐mediated stable free radical polymerization of n‐butyl acrylate (n‐BA) monomers with 2,2′‐azobisisobutyronitrile (AIBN). It was found that the number‐average molecular weight of polymers could reach about ten thousand with a narrow polydispersity index (PDI) of 1.4 in a few minutes, which was faster than other systems reported previously. But, at higher conversion, the molecular weight distribution of polymers became broad, and a bimodal distribution occurred. The macro‐initiators isolated from the former polymers with narrow PDI could be extended by polymerization with monomers by the addition of DDBSA. Furthermore, a proposed kinetic model demonstrated that the decay of the concentration of DDBSA would reduce the living polymer concentration and retard the growth of the polymers, which could be further propagated by the supplement of DDBSA. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 42–49, 2005

ABSTRACT:In this work, a generalized mathematical model was developed to estimate the variation of particle concentration during the entire course of soapless emulsion polymerization of methyl methacrylate with ferrofluid. Two mechanisms for the nucleation and growth of particles throughout the polymerization reaction were discussed: Mechanism I -seeded polymerization; and Mechanism IIself-nucleation polymerization. Here, the self-nucleation included homogeneous nucleation and micelle nucleation. Coagulation between particles, which came from different nucleation mechanisms during the course of polymerization, was considered and included in this model. When appropriate parameters were selected, this model could be successfully used to interpret the variation of particle concentration during the entire reaction. Under different conditions, rate of polymerization, number of radicals in each particle, average molecular weight of polymers, and rate constant of termination were also calculated. All of them explained the experimental results quite well.