Inverse patchy colloids with small patches: fluid structure and dynamical slowing down

TL;DR

This study explores the bulk behavior of inverse patchy colloids with small patches, revealing their fluid structure and dynamical slowdown through molecular dynamics simulations and theoretical comparisons.

Contribution

It provides the first detailed analysis of bulk inverse patchy colloids with small patches, combining simulations with theoretical models for static and dynamic properties.

Findings

Good agreement between simulations and theoretical predictions.

Identification of dynamical slowing down in the fluid phase.

Formation of branched, disordered aggregates in previous confined studies.

Abstract

Inverse Patchy Colloids (IPCs) differ from conventional patchy particles because their patches repel (rather than attract) each other and attract (rather than repel) the part of the colloidal surface that is free of patches. These particular features occur, .e.g., in heterogeneously charged colloidal systems. Here we consider overall neutral IPCs carrying two, relatively small, polar patches. Previous studies of the same model under planar confinement have evidenced the formation of branched, disordered aggregates composed of ring-like structures. We investigate here the bulk behavior of the system via molecular dynamics simulations, focusing on both the structure and the dynamics of the fluid phase in a wide region of the phase diagram. Additionally, the simulation results for the static observables are compared to the Associative Percus Yevick solution of an integral equation approach based on the multi-density Ornstein-Zernike theory. A good agreement between theoretical and numerical quantities is observed even in the region of the phase diagram where the slowing down of the dynamics occurs.