(214l) Using Monte Carlo Simulations to Study Bulk and Interfacial Properties of Ionic Liquids

Rane, K. S., University at Buffalo, The State University of New York
Errington, J. R., University at Buffalo

Ionic liquids show interesting thermo-physical properties due to their unique chemical nature which is characterized by comparative strengths of coulombic and dispersion interactions. In this poster we discuss how molecular simulations are used to study wetting properties of these fluids on solid substrates over a range of conditions. We study wetting phenomena at liquid-vapor saturation conditions and therefore understanding the phase coexistence properties of these fluids is also important. Wetting properties are computed using a free energy based approach that involves performing Monte Carlo simulations to grow a liquid or vapor film on the solid surface of interest. The properties computed from these simulations include interfacial tensions, surface excess energies, and entropies. Expanded ensemble simulations are used to scan a broad range of temperatures and substrate strengths, which enables us to study systems in different wetting regimes. Results are presented for the wetting behavior of different models of ionic liquids on solid substrates. To calculate liquid-vapor saturation properties of ionic liquids over a broad temperature range we use a combination of direct grand canonical and isothermal-isobaric temperature expanded ensemble Monte Carlo simulations. We also show how advanced simulation tools are used to address the challenges generally encountered in simulating complex molecules like those of ionic liquids. We present results for homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][NTf2]) from room temperatures to temperatures close to the estimated critical points.