English Abstract

Synthesis of Monodisperse Polymer Particles in Soap-free Emulsion Polymerization Mikio KONNO Department of Chemical Engineering, Graduate School of Engineering, Tohoku University, Sendai, JAPAN Nippon Gomu Kyokaishi,(2006),79(2),61-66 General Review in Japanese Abstract Current research on soap-free emulsion polymerization is described together with fundamental aspects concerning the mechanism of this polymerization. Conventional methods of soap-free emulsion polymerization were only applicable to the synthesis of monodisperse submicron-sized polymer particles. Previous work, however, pointed out that resultant particle size distributions are strongly dependent on particle coagulation that can be controlled by electrostatic interaction between particles. This basic concept for the particle formation has led to development of a new type of soap-free emulsion polymerization that employs an amphoteric initiator in combination with pH control. This method has enabled the production of highly monodisperse polystyrene particles up to 3ƒÊm in a single stage polymerization. Larger particles can be produced with a simple method of monomer addition to polymerization system after the formation of particles. The soap-free emulsion polymerization is also applicable to the polymerization of methyl methacrylate. Currently, soap-free polymerization methods are widely applied to the synthesis of monodisperse composite particles. The examples given are magnetic polymer latex, silica/polystyrene core-shell particles, bell-shaped hollow core-shell particles and multilayered gold/silica/polystyrene core-shell particles. Keywords: Soap-free emulsion polymerization, Monodisperse particle, Amphoteric initiator, Monomer addition method, Composite particle

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