Sulfanion-initiated open-vessel anionic ring-opening polymerization (AROP) of N-sulfonyl aziridines

Anionic ring-opening polymerization (AROP) of N-sulfonyl aziridines is an important synthetic route to linear polyethyleneimine (PEI) and its derivatives. In most cases, inert atmosphere and dry solvent were needed because of the oxygen- and water-sensitive initiators/catalysts used. Therefore, the AROP of N-sulfonyl aziridines that can be entirely operated in air atmosphere is still a challenging task. Herein, we report a series of sulfanions, including xanthates, dithiocarbamates, dithiobenzoates, thioacetates, and thiolates, as the initiators for the AROP of N-sulfonyl aziridines. Due to their good stability, open-vessel polymerization was achieved with high livingness, affording a range of well-defined α-, ω-telechelic poly(N-sulfonyl aziridine) homopolymers and block copolymers with narrow dispersities and tunable molecular weights. The α-end group of these polyaziridines was readily converted to thiol group, which enabled further post-polymerization functionalization with benzyl acrylate and poly(ethylene glycol) via thiol-ene click chemistry. The establishment of open-vessel sulfanion-initiated AROP of N-sulfonyl aziridines thus lays a solid foundation for the bulk preparation and application of poly(N-sulfonyl aziridine)s and PEI derivatives.