Anionic Ring-Opening Polymerizations of N-Sulfonylaziridines in Ionic Liquids
2022
Giri, Chandan | Sisk, Sarah E. | Reisman, Louis | Kammakakam, Irshad | Bara, J. E. (Jason E.) | West, Kevin N. | Rabideau, Brooks D. | Rupar, Paul A.
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 solvent-transfer reactions. In the phosphonium IL [P₆,₆,₆,₁₄][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.
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