One-Pot Preparation of ABA-Type Block-Graft Copolymers via a Combination of Click Chemistry with Atom Transfer Nitroxide Radical Coupling Reaction

A new strategy for the one-pot preparation of ABA-type block-graft copolymers via a combination of Cu-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry with atom transfer nitroxide radical coupling (ATNRC) reaction was reported. First, sequential ring-opening polymerization of 4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (GTEMPO) and 1-ethoxyethyl glycidyl ether provided a backbone with pendant TEMPO and ethoxyethyl-protected hydroxyl groups, the hydroxyl groups could be recovered by hydrolysis and then esterified with 2-bromoisobutyryl bromide, the bromide groups were converted into azide groups via treatment with NaN(3). Subsequently, bromine-containing poly(tert-butyl acrylate) (PtBA-Br) was synthesized by atom transfer radical polymerization. Alkyne-containing polystyrene (PS-alkyne) was prepared by capping polystyryl-lithium with ethylene oxide and subsequent modification by propargyl bromide. Finally, the CuAAC and ATNRC reaction proceeded simultaneously between backbone and PtBA-Br, PS-alkyne. The effects of catalyst systems on one-pot reaction were discussed. The block-graft copolymers and intermediates were characterized by size-exclusion chromatography, (1)H NMR, and FT-IR in detail. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5430-5438, 2010