A versatile approach for the preparation of end-functional polymers and block copolymers by stable radical exchange reactions

A versatile strategy for the preparation of end-functional polymers and block copolymers by radical exchange reactions is described. For this purpose, first polystyrene with 2,2,6,6-tetramethylpiperidine-1-oxyl end group (PS-TEMPO) is prepared by nitroxide-mediated radical polymerization (NMRP). In the subsequent step, these polymers are heated to 130 °C in the presence of independently prepared TEMPO derivatives bearing hydroxyl, azide and carboxylic acid functionalities, and polymers such as poly(ethylene glycol) (TEMPO-PEG) and poly(ε-caprolactone) (TEMPO-PCL). Due to the simultaneous radical generation and reversible termination of the polymer radical, TEMPO moiety on polystyrene is replaced to form the corresponding end-functional polymers and block copolymers. The intermediates and final polymers are characterized by ¹H NMR, UV, IR, and GPC measurements.