Macromolecular design of alkoxyamine-containing radically reactive polymers based on dynamic covalent chemistry

In the last decades, dynamic covalent chemistry attracts much attention for creating novel molecules and macromolecules, which are stable under mild conditions and are responsive to external stimuli such as heating, light irradiation and catalyst addition. Alkoxyamine derivatives derived from 2,2,6,6-tetramethylpiperidine-l-oxy (TEMPO, a stable free radical) have weak C-ON bonds and they reversibly cleave and reform upon heating involving a radical. A mixture of alkoxyamine derivatives is able to equilibrate thermally, meaning that the alkoxyamine derivatives are considered dynamic covalent linkages during heating. In this paper, the recent progress in the macromolecular design and radical reactions of main-chain type, side-chain type, cross-linked, and star-shaped polymers with alkoxyamine units is comprehensively introduced. Unlike conventional polymers, the structures and constituents of alkoxyamine-based dynamic covalent polymers can be reorganized during heating and they are applicable to create a new class of reactive polymeric materials.