Molecular dynamics investigation of wetting-dewetting behavior of model carbon material by 1-butyl-3-methylimidazolium acetate ionic liquid nanodroplet.

Abstract

In order to comprehend the wetting-dewetting behavior of a solid surface by a liquid, it is crucial to contemplate both the surface flexibility and the interactions involved. Herein, by employing molecular dynamics simulations, we aim to understand the structural changes in 1-butyl-3-methylimidazolium acetate ([bmim][Ac]) ionic liquid (IL) nanodroplets on model carbon sheets with varying IL-sheet interaction potentials along with the flexibility of the carbon sheet. The extent of the wetting is estimated by computing the average contact angle formed by [bmim][Ac] nanodroplets on the sheet surface. We observe that the wetting-dewetting behavior of the sheet and its affinity toward [bmim]+ and [Ac]- depend not only on the IL-sheet interaction but also on its flexibility or rigidity. The extent of wetting is observed to be consistently greater for the rigid surface in the entire range of IL-sheet interaction potentials studied herein. Although in the adlayer, [bmim]+ rings and [Ac]- anions prefer to be parallel to the carbon surface, the ordering of the [bmim]+ rings is highly affected by the introduction of flexibility in the carbon surface. Enhanced structural and orientational ordering of imidazolium rings of [bmim]+ cations in the adlayer of the rigid surface is observed, supporting the comprehension of greater wetting extent of the rigid surface by the IL droplet.