Polymers in Ionic Liquids

Ionic liquids have generated considerable excitement for their varied potential applications and their interesting physical properties. The viability of ionic liquids (ILs) in materials applications is limited by their lack of mechanical integrity, which may be provided by mixing them with a polymeric material. Recent experiments on polymers in ILs have unearthed a wealth of interesting phenomena that raise fundamental questions. This talk focuses on computational studies of PEO in imidazolium ILs. We develop a physically motivated first principles force field; this force field is in quantitative agreement with experiment with no adjustable parameters. The calculations emphasize the importance of polarization but show little evidence for charge transfer. Based on the same quantum calculations we develop a hierarchy of united atom models with decreasing resolution and increasing computational efficiency. Atomistic simulations show a lower critical solution temperature in the PEO in [BMIM] [BF₄] system and provide physical insight into the mechanism based on entropic effects.