Post-polymerization modification by nitroxide radical coupling

Post-polymerization modification is an attractive approach to extend applications and convert commodity plastics into products with new, desirable and tunable properties. Among the post-polymerization modification methods, the nitroxide radical coupling (NRC) reaction has shown to be a convenient and versatile way to graft specific functionalities onto polymer chains and to control the onset and yield of polymer crosslinking during peroxide-initiated processes. The use of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its derivatives as controllers of scorch in crosslinking and as functionalizers in functionalization reactions is thoroughly described. Examples are also given about graft polymerization from macroalkoxyamines generated by NRC and grafting of nitroxides by irradiation processes. In addition, this review attempts to demonstrate the broad applications of NRC reaction on the preparation of polymers with a multitudinous of functionalities and elaborate architectures. The examples discussed herein concern the use of atom transfer and single electron transfer nitroxide radical coupling (ATNRC and SETNRC) reactions to design a variety of polymers with asymmetrical structure and of the radical crossover reaction, based on the alkoxyamine dynamic covalent bond, to generate reversible polymer structures and switchable functional polymers.