Thermodynamics of Ionic Liquid Cosolvent Mixtures Using Molecular Dynamics Simulation: 1-Ethyl-3-methylimidazolium Acetate

Abstract

Molecular dynamics (MD) simulations were conducted to calculate the binary mixture properties (excess molar heats and volumes) of 1-ethyl-3-methylimidazolium acetate [EMIM][Ac] with six polar covalent molecules (acetic acid, acetone, chloroform, dimethyl sulfoxide, isopropyl alcohol, and methanol) over the entire composition range. All of the binary mixtures of [EMIM][Ac] with cosolvents reported negative volumes of mixing over the entire composition range while releasing heat (exothermic heats of mixing), except for the acetone mixture, which had miscibility issues at higher concentrations (xacetone ≥ 0.6). These results were attributed to the nature, size, and structure of the molecules as well as the nature of the interaction between the mixture components. Further, aggregation of the ionic liquid (IL) at higher concentrations of the cosolvent added to the above observed effects, except for the acetic acid mixture. These results have been interpreted in terms of hydrogen-bonding and intermolecular inte...