| Abstract: | A trifunctional initiator, 2‐phenyl‐2‐(2,2,6,6‐tetramethyl)‐1‐piperidinyloxy] ethyl 2,2‐bismethyl(2‐bromopropionato)] propionate, was synthesized and used for the synthesis of miktoarm star AB2 and miktoarm star block AB2C2 copolymers via a combination of stable free‐radical polymerization (SFRP) and atom transfer radical polymerization (ATRP) in a two‐step or three‐step reaction sequence, respectively. In the first step, a polystyrene (PSt) macroinitiator with dual ω‐bromo functionality was obtained by SFRP of styrene (St) in bulk at 125 °C. Next, this PSt precursor was used as a macroinitiator for ATRP of tert‐butyl acrylate (tBA) in the presence of Cu(I)Br and pentamethyldiethylenetriamine at 80 °C, affording miktoarm star (PSt)(PtBA)2 where PtBA is poly(tert‐butyl acrylate)]. In the third step, the obtained St(tBA)2 macroinitiator with two terminal bromine groups was further polymerized with methyl methacrylate by ATRP, and this resulted in (PSt)(PtBA)2(PMMA)2‐type miktoarm star block copolymer where PMMA is poly(methyl methacrylate)] with a controlled molecular weight and a moderate polydispersity (weight‐average molecular weight/number‐average molecular weight < 1.38). All polymers were characterized by gel permeation chromatography and 1H NMR. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2542–2548, 2003 |
