Thermo-responsive fluorescent micelles from amphiphilic A3B miktoarm star copolymers prepared via a combination of SET-LRP and RAFT polymerization

Abstract

A novel amphiphilic A3B miktoarm star copolymer poly(N-isopropylacrylamide)3-poly(N-vinylcarbazole) ((PNIPAAM)3(PVK)) was successfully synthesized by a combination of single-electron transfer living radical polymerization (SET-LRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. First, the well-defined three-armed poly(N-isopropylacrylamide) (PNIPAAM)3 was prepared via SET-LRP of N-isopropylacrylamide in acetone at 25 °C using a tetrafunctional bromoxanthate iniferter (Xanthate-Br3) as the initiator and Cu(0)/PMDETA as a catalyst system. Secondly, the target amphiphilic A3B miktoarm star copolymer ((PNIPAAM)3(PVK)) was prepared via RAFT polymerization of N-vinylcarbazole (NVC) employing (PNIPAAM)3 as the macro-RAFT agent. The architecture of the amphiphilic A3B miktoarm star copolymers were characterized by GPC, 1H-NMR spectra. Furthermore, the fluorescence intensity of micelle increased with the temperature and had a good temperature reversibility, which was investigated by dynamic light scattering (DLS), fluorescent and UV-vis spectra. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4268–4278, 2010