Electrowetting diminishes contact line friction in molecular wetting

TL;DR

This study uses molecular dynamics simulations to show that electrowetting reduces contact line friction by extending the electric field's influence, facilitating ion and molecule movement at the contact line.

Contribution

It demonstrates how electrowetting diminishes contact line friction by analyzing electric field effects on molecular interactions at the contact line.

Findings

Electrowetting reduces contact line friction.

Electric field extends interaction range for ions and molecules.

Friction decrease is consistent across droplet sizes and solutions.

Abstract

We use large-scale molecular dynamics to study dynamics at the three-phase contact line in electrowetting of water and electrolytes on no-slip substrates. Under the applied electrostatic potential the line friction at the contact line is diminished. The effect is consistent for droplets of different sizes as well as for both pure water and electrolyte solution droplets. We analyze the electric field at the contact line to show how it assists ions and dipolar molecules to advance the contact line. Without an electric field, the interaction between a substrate and a liquid has a very short range, mostly affecting the bottom, immobilized layer of liquid molecules which leads to high friction since mobile molecules are not pulled towards the surface. In electrowetting, the electric field attracts charged and polar molecules over a longer range which diminishes the friction.