Radical polymerization of polyoxyethylene macromonomers in disperse systems

Polymerization in disperse systems is a technique which allows one to prep are ultrafine and microsize latex particles, as well, and random, comb-like , comb-like, star-like, and graft copolymers. This article presents a revie w of the current literature in the field of the surfactant-free dispersion or emulsifier-free emulsion polymerization and copolymerization of the poly oxyethylene unsaturated macromonomers. The key factor for the preparation o f 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 ar ises with the use of reactive surfactants which contain a polymerizable gro up. The reactive surfactants are incorporated into the polymer matrix or th e particle surface layer which prevents them from subsequent migration. Tog ether with a short introduction into some kinetic aspects of radical polyme rization of traditional monomers in dispersion, emulsion, miniemulsion and microemulsion, we focus mainly on the organized aggregation of amphiphilic polyoxyethylene macromonomers and radical copolymerization of polyoxyethyle ne macromonomers with styrene and alkyl (meth)acrylates. We discuss mechani sms of particle growth, particle nucleation, the growth and termination pol ymer chains, and colloidal stability. Effects of initiator, macromonomer, d iluent, 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 polymerizat ion and particle size are evaluated. Variation of molecular weight with the reaction conditions is also discussed.