Steric effect of water molecule clusters on electrostatic interaction and electroosmotic transport in aqueous electrolytes: a mean-field approach

TL;DR

This study uses a mean-field theoretical approach to analyze how water molecule cluster sizes influence electrostatic interactions and electroosmotic flow in nanofluidic channels, revealing that smaller clusters enhance flow and larger clusters weaken electrostatic forces.

Contribution

It introduces a mean-field model that accounts for water cluster sizes, providing new insights into their effects on electrostatic and electroosmotic behaviors in nanofluidic systems.

Findings

Smaller water clusters lead to stronger electroosmotic transport.

Larger water clusters decrease electrostatic interaction strength.

The model offers a quantitative framework for water cluster effects.

Abstract

We theoretically study the size effect of water molecule clusters not only on electrostatic interaction between two charged surfaces in an aqueous electrolyte but also on electroosmotic transport in a nanofluidic channel. Applying a free energy based mean-field approach accounting for different sizes of ions and water molecule clusters, we derive a set of coupled equations to compute electrostatic and electroosmotic properties between charged surfaces. We verify that the smaller the size of a water cluster, the stronger the electroosmotic transport in nanofluidic channels. In addition, we find that an increase in size of a water cluster yields a decrease in electrostatic interaction strength between similar or oppositely charged planar surfaces.