History of nitroxide mediated polymerization in Canada

Abstract

AbstractNitroxide mediated polymerization (NMP), sometimes known as stable free radical polymerization (SFRP), is considered one of the main types of reversible deactivation radical polymerization (RDRP) that have emerged as a major advance in polymer synthesis in the past 30 years. This review examines NMP's development from a uniquely Canadian perspective. Inspired by reports of a reversible equilibrium between the TEMPO persistent radical and a growing polymeric radical chain, researchers at the Xerox Research Centre of Canada (XRCC) reported radical polymerizations of styrene with hallmarks typically associated with living polymerizations: linear degree of polymerization of with conversion, narrow molecular weight distributions, and ability to re‐initiate the chain end with additional monomer. This effort expanded to polymerizations in dispersed aqueous media (eg, miniemulsion) and to polymerizations directed for various architectures (block, graft, star), but NMP was ultimately generally limited to styrenic monomers. Consequently, NMP trailed other RDRP methods, such as atom transfer radical polymerization (ATRP) and reversible addition fragmentation transfer polymerization (RAFT), due to its limited monomer choice. With the advent of second‐generation alkoxyamine initiators, however, the range of monomers polymerizable in a controlled manner greatly expanded to include acrylates, acrylamides, and eventually methacrylates (under certain conditions), providing renewed impetus towards using NMP. Consequently, Canadian researchers applied these new alkoxyamines for more versatile polymers, resulting in products such as stimuli‐responsive polymers, CO2‐switchable latexes, bio‐hybrid composites, organic photovoltaic materials, and photolithographic materials. The chronological progression of the developments in NMP from various Canadian laboratories highlights these achievements in new polymeric materials.