Interplay of anisotropy in shape and interactions in charged platelet suspensions

TL;DR

This study uses Monte-Carlo simulations to explore how anisotropic electrostatic interactions influence the phase behavior and dynamics of charged colloidal disks, revealing complex structures and their dependence on charge and experimental conditions.

Contribution

It introduces a detailed simulation approach incorporating anisotropic screened Coulomb potentials to analyze phase behavior and dynamics of charged platelets, connecting theoretical predictions with experiments.

Findings

Identification of various liquid-crystalline phases.

Prediction of novel alternating nematic-antinematic structures.

Analysis of how charge affects structural and dynamical properties.

Abstract

Motivated by the intriguing phase behavior of charged colloidal platelets, we investigate the structure and dynamics of charged repulsive disks by means of Monte-Carlo simulations. The electrostatic interactions are taken into account through an effective two-body potential, obtained within the non-linear Poisson-Boltzmann formalism, which has the form of anisotropic screened Coulomb potential. Recently, we showed that the original intrinsic anisotropy of the electrostatic potential in competition with excluded volume effects leads to a rich phase behavior that not only includes various liquid-crsytalline phases but also predicts the existence of novel structures composed of alternating nematic-antinematic sheets. Here, we examine the structural and dynamical signatures of each of the observed structures for both translational and rotational degrees of freedom. Finally, we discuss the influence of effective charge value and our results in relation to experimental findings on charged platelet suspensions.