Anionic Ring-Opening Polymerizations of N-Sulfonylaziridines in Ionic Liquids

The anionic ring-opening polymerization (AROP) of sulfonylaziridines in ionic liquids (ILs) is reported. In imidazolium ILs, the polymerization of 2-methyl-N-tosylaziridine (TsMAz) is not controlled due to poor solubility at higher degrees of polymerization and apparent solventtransfer reactions. In the phosphonium IL [P-6,P-6,P-6,P-14][Tf2N], the polymerization of TsMAz is controlled and living, and capable of sequential block copolymer synthesis. The polymerization of TsMAz is first-order with respect to monomer in ILs, with rates slower than observed in traditional aprotic polar solvents (e.g., DMF). Molecular dynamics simulations were used to compare DMF vs IL solutions consisting of BuN(K)Ts (as a model for the propagating chain end). The molecular dynamics simulations suggest better monomer/anion organization in DMF and poorer mobilities in the ILs; both are consistent with observed reduction in polymerization rates in the ILs compared to DMF.

Automated summary

The study explores the anionic ring-opening polymerization of sulfonylaziridines in ionic liquids. In imidazolium ILs, the polymerization is not controlled due to poor solubility and solvent-transfer reactions, while in phosphonium ILs, it is controlled and living, allowing for sequential block copolymer synthesis. The slower polymerization rates in ILs compared to traditional polar solvents like DMF may be attributed to better monomer/anion organization in DMF and poorer mobilities in ILs.