Polar Liquids at Charged Interfaces: A Dipolar Shell Theory

TL;DR

This paper introduces a continuum dipolar shell theory to model the structure and dielectric behavior of polar liquids at charged interfaces, linking molecular properties to macroscopic phenomena.

Contribution

It develops a novel continuum model that captures dielectric screening and oscillatory charge profiles of polar liquids at interfaces, validated against molecular dynamics insights.

Findings

Predicts anisotropic dielectric tensor at interfaces

Derives formulas for decay lengths of molecular and ionic profiles

Explores effects on capacitance and hydration forces

Abstract

The structure of polar liquids and electrolytic solutions, such as water and aqueous electrolytes, at interfaces underlies numerous phenomena in physics, chemistry, biology, and engineering. In this work, we develop a continuum theory that captures the essential features of dielectric screening by polar liquids at charged interfaces, including oscillations in charge and mass, starting from the molecular properties of the solvent. The theory predicts an anisotropic dielectric tensor of interfacial polar liquids previously studied in molecular dynamics simulations. We explore the effect of the interfacial polar liquid properties on the capacitance of the electrode/electrolyte interface and on hydration forces between two plane-parallel polarized surfaces. In the linear response approximation, we obtain simple formulas for the characteristic decay lengths of molecular and ionic profiles at the interface.