Video Upload Options

Nitroxide-mediated polymerization (NMP) is a reversible-deactivation radical polymerization in which a stable nitroxide radical reversibly caps the propagating carbon-centered radical as an alkoxyamine, thereby establishing a dormant–active equilibrium that controls chain growth ^[1]. The concept is bounded by three structural elements: a nitroxide persistent radical, a C–ON alkoxyamine linkage that undergoes thermally induced homolysis, and a conventional radical-propagation step that occurs only while the chain end is uncapped. Essential kinetic features are a low stationary concentration of propagating radicals, suppression of irreversible biradical termination relative to an uncontrolled radical polymerization, and a linear evolution of molecular weight with conversion when initiation is efficient ^[1]. Side reactions include N–O versus O–C cleavage of the alkoxyamine, which can divert the equilibrium away from clean reinitiation ^[2]. NMP is distinguished from atom-transfer radical polymerization and RAFT by the absence of a transition-metal catalyst and of a degenerative-transfer agent; control is exerted solely by the persistent nitroxide. The same capping equilibrium can be used to grow polymer brushes from a surface-bound alkoxyamine and to assemble block or alternating architectures after orthogonal chain-end functionalization ^[3][4].