Radical polymerization of polyoxyethylene macromonomers in disperse systems

Abstract

Polymerization in disperse systems is a technique which allows one to prepare ultrafine and microsize latex particles, as well, and random, comb-like, comb-like, star-like, and graft copolymers. This article presents a review of the current literature in the field of the surfactant-free dispersion or emulsifier-free emulsion polymerization and copolymerization of the polyoxyethylene unsaturated macromonomers. The key factor for the preparation of polymer dispersion is the type of emulsifier and its concentration. When conventional surfactants are used, the high amount of stabilizer is needed to prepare a fine polymer dispersion. Conventional surfactants are held on the particle surface by the physical factors. An interesting alternative arises with the use of reactive surfactants which contain a polymerizable group. The reactive surfactants are incorporated into the polymer matrix or the particle surface layer which prevents them from subsequent migration. Together with a short introduction into some kinetic aspects of radical polymerization of traditional monomers in dispersion, emulsion, miniemulsion and microemulsion, we focus mainly on the organized aggregation of amphiphilic polyoxyethylene macromonomers and radical copolymerization of polyoxyethylene macromonomers with styrene and alkyl (meth)acrylates. We discuss mechanisms of particle growth, particle nucleation, the growth and termination polymer chains, and colloidal stability. Effects of initiator, macromonomer, diluent, continuous phase type and concentration of initiator, macromonomer and additives, the surface activity of macromonomer, the type of organized association of macromonomer or graft copolymer molecules on the polymerization and particle size are evaluated. Variation of molecular weight with the reaction conditions is also discussed. © Springer-Verlag Berlin Heidelberg 1999.