Influence of Confinement on Flow and Lubrication Properties of a Salt Model Ionic Liquid Investigated with Molecular Dynamics

TL;DR

This study uses molecular dynamics simulations to explore how confinement affects the flow, lubrication, and structural transitions of ionic liquids between solid plates under shear and cyclic loads.

Contribution

It provides new insights into the dynamic behavior and structural changes of ionic liquids under confinement, including wall slip effects and phase transitions.

Findings

Wall slip significantly influences force response during deformation.

Interaction with walls governs ionic liquid behavior in confined flow.

Ionic liquid transitions from dense to ordered/solidified state under load.

Abstract

We present a molecular dynamics study of the effects of confinement on the lubrication and flow properties of ionic liquids. We use a coarse-grained salt model description of ionic liquid as a lubricant confined between finite solid plates and subjected to two dynamic regimes: shear and cyclic loading. The impact of confinement on the ion arrangement and mechanical response of the system has been studied in detail and compared to static and bulk properties. The results have revealed that the wall slip has a profound influence on the force built--up as a response to mechanical deformation and that at the same time in the dynamic regime interaction with the walls represents a principal driving force governing the behavior of ionic liquid in the gap. We also observe a transition from a dense liquid to an ordered and potentially solidified state of the ionic liquid taking place under variable normal loads and under shear.