3-miktoarm star terpolymers using triple click reactions: Diels–Alder, copper-catalyzed azide-alkyne cycloaddition, and nitroxide radical coupling reactions



Well-defined linear furan-protected maleimide-terminated poly(ethylene glycol) (PEG-MI), tetramethylpiperidine-1-oxyl-terminated poly(ε-caprolactone) (PCL-TEMPO), and azide-terminated polystyrene (PS-N3) or -poly(N-butyl oxanorbornene imide) (PONB-N3) were ligated to an orthogonally functionalized core (1) in a two-step reaction mode through triple click reactions. In a first step, Diels–Alder click reaction of PEG-MI with 1 was performed in toluene at 110 °C for 24 h to afford α-alkyne-α-bromide-terminated PEG (PEG-alkyne/Br). As a second step, this precursor was subsequently ligated with the PCL-TEMPO and PS-N3 or PONB-N3 in N,N-dimethylformamide at room temperature for 12 h catalyzed by Cu(0)/Cu(I) through copper-catalyzed azide-alkyne cycloaddition and nitroxide radical coupling click reactions, yield resulting ABC miktoarm star polymers in a one-pot mode. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012