Molecular Insights into the Electrowetting Behavior of Aqueous Ionic Liquid

TL;DR

This study uses molecular dynamics simulations to investigate how electric fields influence the wetting behavior of nanoscale ionic liquid droplets on graphite, revealing configuration transformations and asymmetric wetting depending on IL type and concentration.

Contribution

It provides new insights into the electrowetting behavior of ionic liquids on solid surfaces under electric fields, highlighting the effects of IL type and concentration.

Findings

Configuration transformation at E=0.08 V/Å for all ILs and water.

Asymmetric wetting observed for hydrophilic IL at specific electric fields.

Electric field impacts density distribution, contact angle, and hydrogen bonding.

Abstract

Molecular dynamics simulations were employed to study the wetting behavior of nanoscale aqueous hydrophilic and hydrophobic Imidazolium based ionic liquid (IL) droplets on a solid graphite substrate subjected to the perpendicular electric field. Imminent transformation in the droplet configuration was observed at E = 0.08 V/{\AA} both for hydrophobic ILs [EMIM][NTF2] and SPC/E water droplets. However, for hydrophilic, [EMIM][BF4], the droplet wets asymmetrically within electric field E = 0.09 V/{\AA} for lower weight percentages of ILs and E = 0.1 V/{\AA} at a higher weight percentage of ILs (i.e., 50wt%), because of the strong interaction of ILs with the sheet. We explore the impact of electric-field through various parameters such as mass density distribution, contact angle, orientation, and hydrogen bonds. Keywords: electro-wetting; contact angle; aqueous hydrophilic and hydrophobic Imidazolium ILs, molecular dynamic simulation