(5by) Multiscale Modeling Studies of Complex Fluid Mixtures

Ionic liquids (ILs) have been proposed for use in a wide variety of potential industrial applications including fuel cells, catalysis, as heat transfer fluids, and as (potentially) environmentally benign replacement solvents for industrial reactions and separation processes. A solid understanding of the structure-property relationships ILs are necessary to be able to design an ionic liquid that can be used for a specific industrial task, will not pose a serious health hazard if released in a chemical spill, and can be produced in large quantities at a low cost. In this work computational methods, including ab initio quantum mechanical (QM) calculations and molecular dynamics (MD) simulations are used to study a variety of ionic liquid systems, including a pure IL, an aqueous IL mixture, and mixtures of ILs with 1-butanol.

Coarse-graining Methods For Developing Mesoscale Molecular Models

Atomistic simulations alone are not yet capable of accessing the wide range of length and time scales needed to understand many ionic liquid and other soft matter systems (e.g. colloidal and micellar solutions, protein and polymer solutions, etc.). A current challenge is to coarse grain such systems by developing definitions of effective potentials that can be determined from atomistic simulations (e.g. molecular dynamics), and then used in mesoscale simulations which can access these long time and length scales. A variety of methods, ranging from the use of purely empirical ad hoc potentials, to use of effective potentials that rigorously match the partition function, have been proposed. In this work we test three of the most promising of these approaches against simulation data for Lennard-Jones binary mixtures for molecules A (solute) and B (solvent) having a range of size ratios, σ_AA/σ_BB. The solvent, B, is fully coarse-grained out, creating an implicit solvent for the larger component, A. A comparison of the accuracy and computational expense of all three methods will be discussed.