Importance of Varying Permittivity on the Conductivity of Polyelectrolyte Solutions

TL;DR

This paper introduces a new algorithm that accounts for local permittivity variations in polyelectrolyte solutions, significantly improving the accuracy of conductivity simulations compared to traditional constant permittivity models.

Contribution

The authors develop a novel algorithm to model spatial and temporal permittivity variations, enabling more accurate simulation of ion distribution and conductivity in polyelectrolyte solutions.

Findings

The new algorithm accurately reproduces experimental conductivity data.

Permittivity gradients influence ion distribution near polymers.

Constant permittivity models fail to capture key behaviors.

Abstract

Dissolved ions can alter the local permittivity of water, nevertheless most theories and simulations ignore this fact. We present a novel algorithm for treating spatial and temporal variations in the permittivity and use it to measure the equivalent conductivity of a salt-free polyelectrolyte solution. Our new approach quantitatively reproduces experimental results unlike simulations with a constant permittivity that even qualitatively fail to describe the data. We can relate this success to a change in the ion distribution close to the polymer due to the built-up of a permittivity gradient.