Preparation of nano-sized poly(ethylene oxide) star microgels via reversible addition-fragmentation transfer polymerization in selective solvents

Abstract

Poly(ethylene oxide) (PEO) star microgels with a cross-linked polystyrene core were successfully prepared by reversible addition-fragmentation transfer polymerization of styrene (St) and divinylbenzene (DVB) with dithiobenzoate-terminated PEO monomethyl ether (DTB-MPEO) as macro chain transfer agent in mixtures of ethanol and tetrahydrofuran (THF). The formation of star polymers was affected by polymerization time, solvents and St:DVB:DTB-MPEO molar ratios. Narrow polydispersed star microgels with high molecular weight were obtained under appropriate polymerization conditions. Transmission electron micrographs suggest that PEO star polymers could form nano-size spherical micelles in mixtures of water and THF, which further demonstrates the amphiphilic nature of the star polymers. © 2006 Society of Chemical Industry.