Alcohol- and Water-Tolerant Living Anionic Polymerization of Aziridines

Living anionic polymerization gives access to well-defined polymers, but it demands strict purification of reagents and solvents. This work presents the azaanionic polymerization (AAROP) of aziridines as a robust living polymerization technique, with the ease of controlled radical polymerizations. AAROP does not require inert atmosphere and remains living in the presence of large amounts of water or alcohols. Mesyl-, tosyl-, or brosyl-activated aziridines were polymerized with up to 100-fold excess of a protic impurity with respect to the initiator and still being active for chain extension. This allowed the preparation of polyols by anionic polymerization without protective groups, as only minor initiation occurred from the alcohols. The tolerance toward protic additives lies in the electron-withdrawing effect of the activating groups, decreasing the basicity of the propagating species, while maintaining a strong nucleophilic character. In this way, competing alcohols and water are only slightly involved in the polymerization, making living anionic polymerization an easy-to-conduct technique to well-defined polyamides and -amines.