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

Abstract

Abstract A novel amphiphilic A 3 B 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‐Br 3 ) as the initiator and Cu(0)/PMDETA as a catalyst system. Secondly, the target amphiphilic A 3 B 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 A 3 B miktoarm star copolymers were characterized by GPC, 1 H‐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