Structural fine-tuning of zwitterionic salts for the discovery of LCST-type thermoresponsive materials

Abstract

In our current work, we discovered N-triflimide (NTf)-based zwitterionic ionic liquids (ZILs) exhibiting LCST phase transitions in water and showed an ability to further fine tune their structure to afford N-pentafluoroethylsulfonimide (NPf)-based ZILs displaying T_c values attractive for potential applications. This report is, to the best of our knowledge, the first one on both NTf- and NPf-based ZILs as small-molecule thermoresponsive materials for which their mixing with and separation from water triggered by changes in temperature were shown to be fully reversible.