Poisson-Boltzmann cell model for heterogeneously charged colloids

TL;DR

This paper presents a generalized Poisson-Boltzmann cell model for spherical colloids with heterogeneous surface charges, predicting isotropic phases without orientational ordering in liquid-like states.

Contribution

It introduces a novel cell model for heterogeneously charged colloids, extending previous models for uniform charges and linking to liquid crystal theories.

Findings

Model predicts no orientational ordering without positional order.

Heterogeneous charges lead to isotropic liquid-like phases.

Generalizes existing cell models for charged colloids.

Abstract

We introduce the Poisson-Boltzmann cell model for spherical colloidal particles with a heterogeneous surface charge distribution. This model is obtained by generalizing existing cell models for mixtures of homogeneously charged colloidal spheres. Our new model has similar features as Onsager's second-virial theory for liquid crystals, but it predicts no orientational ordering if there is no positional ordering. This implies that all phases of heterogeneously charged colloids that are liquid-like with respect to translational degrees of freedom are also isotropic with respect to particle orientation.