Living Anionic Copolymerization of 1‑(Alkylsulfonyl)aziridines to Form Poly(sulfonylaziridine) and Linear Poly(ethylenimine)

The anionic ring-opening copolymerization of 1-(methylsulfonyl)­aziridine (MsAz) and 1-(sec-butylsulfonyl)­aziridine (^sBsAz) produces a soluble random copolymer P­(MsAz-r-^sBsAz), which can subsequently be converted to linear poly­(ethylenimine) (lPEI). The copolymerization of MsAz and ^sBsAz is living and allows for the synthesis of copolymers with low molecular weight distributions. Sequential anionic polymerization of MsAz and ^sBsAz with 2-methyl-1-(methylsulfonyl)­aziridine (MsMAz) creates P­(MsAz-r-^sBsAz)-b-P­(MeMsAz). Removal of the sulfonyl groups from P­(MsAz-r-^sBsAz)-b-P­(MsMAz) gives lPEI-b-poly­(propylenimine). For the first time, lPEI can be synthesized by a controlled anionic polymerization.