Dynamic heterogeneities in attractive colloids

TL;DR

This paper investigates the formation of colloidal gels through Molecular Dynamics simulations, revealing how dynamic heterogeneities evolve with volume fraction and temperature, highlighting the role of persistent clusters.

Contribution

It introduces a new mean cluster size measure that accurately describes dynamic susceptibility in colloidal gels, linking structure and dynamics.

Findings

Dynamic susceptibility shows a large plateau at low volume fractions.

Persistent clusters dominate the dynamic heterogeneities.

A crossover from plateau to peak in susceptibility occurs with increasing volume fraction.

Abstract

We study the formation of a colloidal gel by means of Molecular Dynamics simulations of a model for colloidal suspensions. A slowing down with gel-like features is observed at low temperatures and low volume fractions, due to the formation of persistent structures. We show that at low volume fraction the dynamic susceptibility, which describes dynamic heterogeneities, exhibits a large plateau, dominated by clusters of long living bonds. At higher volume fraction, where the effect of the crowding of the particles starts to be present, it crosses over towards a regime characterized by a peak. We introduce a suitable mean cluster size of clusters of monomers connected by "persistent" bonds which well describes the dynamic susceptibility.