Phase behavior of polymer/ionic liquids mixture: a molecular dynamics study

The phase behavior of polymers in ionic liquids is of practical importance for use in polymer solid state batteries and temperature sensors, where the ionic liquid allows a tuning of the solution properties. There are fundamental questions regarding the LCST phase behavior: The critical point is at high polymer concentrations, and the critical temperature is insensitive to molecular weight. In this work, we study the phase behavior a mixture of poly(ethylene oxide) (PEO) and imidazolium-based ionic liquids using a new molecular simulation method we have recently developed. We explore the influence of PEO molecular weight and the C2 methylation of [BMIM] (1-butyl-3-methylimidazolium) cation, [BMMIM] (ternary 1-butyl-2,3-dimethylimidazolium) on the phase diagram. The simulations provide molecular insight into the mechanism of phase separation in these mixtures.