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

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