Simultaneous Dual End-Functionalization of PEG via the Passerini Three-Component Reaction for the Synthesis of ABC Miktoarm Terpolymers

In this article, we demonstrate the Passerini three-component reaction as a simple, effective method for the synthesis of polymers with double functional end groups, which are key precursors for the preparation of ABC miktoarm terpolymers. Thus, via the one-step Passerini reaction of monomethoxy poly(ethylene glycol)-propionaldehyde (PEG-CHO) with 2-bromo-2-methylpropionic acid and propargyl isocyanoacetamide, the PEG chain end was simultaneously functionalized with one atom transfer radical polymerization (ATRP) initiating site and one alkynyl group. The resulting PEG(-alkynyl)-Br was then used for the synthesis of three types of miktoarm ABC terpolymers via two approaches. First, we conducted ATRP of N-isopropylacrylamide (NIPAM), then click reaction with azido-terminated polystyrene (PS-N-3) or poly(tert-butyl acrylate) (PtBA-N-3) and obtained two ABC miktoarm terpolymers PEG(b-PNIPAM)-b-PS and PEG(-b-PNIPAM)-b-PtBA. Alternatively, we conducted single electron transfer living radical polymerization of tBA and click reaction with PS-N-3 simultaneously to give PEG(-b-PtBA)-b-PS. All the polymer precursors and miktoarm terpolymers have been characterized by H-1 NMR, Fourier transform infrared, gel permeation chromatography, demonstrating that both approaches provided well-defined ABC miktoarm terpolymers. (C) 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 865-873