Dipolar Poisson-Boltzmann Equation: Ions and Dipoles Close to Charged Surfaces

TL;DR

This paper extends the Poisson-Boltzmann model to explicitly include solvent dipoles, providing a more accurate description of ion distributions and forces near charged surfaces, with potential implications for electrochemical systems.

Contribution

It introduces a mean-field extension of the Poisson-Boltzmann equation that explicitly accounts for solvent dipoles, applicable to complex charged surface interactions.

Findings

Dipolar effects significantly alter ion distributions.

The model predicts large corrections to inter-plate pressure.

Explicit dipole modeling improves understanding of electrostatic interactions.

Abstract

We present an extension to the Poisson-Boltzmann model where the dipolar features of solvent molecules are taken explicitly into account. The formulation is derived at mean-field level and can be extended to any order in a systematic expansion. It is applied to a two-plate system with oppositely charged surfaces. The ion distribution and profiles in the dipolar order parameter are calculated and can result in a large correction to the inter-plate pressure.