Synthesis of amphiphilic A 2 B star‐shaped copolymers of polystyrene‐ b ‐[poly(ethylene oxide)] 2 via atom transfer nitroxide radical coupling

The amphiphilic A 2 B star‐shaped copolymers of polystyrene‐ b ‐[poly(ethylene oxide)] 2 (PS‐ b ‐PEO 2 ) were synthesized via the combination of atom transfer nitroxide radical coupling (ATNRC) with ring‐opening polymerization (ROP) and atom transfer radical polymerization (ATRP) mechanisms. First, a novel V‐shaped 2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐PEO 2 (TEMPO‐PEO 2 ) with a TEMPO group at middle chain was obtained by ROP of ethylene oxdie monomers using 4‐(2,3‐dihydroxypropoxy)‐TEMPO and diphenylmethyl potassium as coinitiator. Then, the linear PS with a bromine end group (PS‐Br) was obtained by ATRP of styrene monomers using ethyl 2‐bromoisobutyrate as initiator. Finally, the copolymers of PS‐ b ‐PEO 2 were obtained by ATNRC between the TEMPO and bromide groups on TEMPO‐PEO 2 and PS‐Br, respectively. The structures of target copolymers and their precursors were all well‐defined by gel permeation chromatographic and nuclear magnetic resonance ( 1 H NMR). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012