Toward the dynamic phase transition mechanism of a thermoresponsive ionic liquid in the presence of different thermoresponsive polymers

摘要: The influence of two thermoresponsive polymers, poly(N-isopropylacrylamide) (PNIPAM) and poly(N-vinylcaprolactam) (PVCL), on the phase transition behavior a ionic liquid, tributylhexylphosphonium 3-sulfopropylmethacrylate ([P4,4,4,6][MC3S]), was investigated. An obvious distinction observed in LCSTs morphologies [P4,4,4,6][MC3S]–PNIPAM [P4,4,4,6][MC3S]–PVCL aqueous solutions, indicating their large differences dynamic processes. In general, PNIPAM can “break” water structure [P4,4,4,6][MC3S] to decrease temperature, while PVCL “make” increase it. Surprisingly, has an unusual over-hydration before dehydration experiences two-step process solution, which never been reported so far. Further studies revealed that formation strong intra-/inter-molecular hydrogen bonds CO⋯D–N is driving force for LCST phenomenon it dominates separation solution.