Colloidal gelation, percolation and structural arrest

TL;DR

This study uses molecular dynamics to explore how competing attractive and repulsive forces lead to gelation and structural arrest in colloidal suspensions, highlighting the importance of long-lived clusters and bond dynamics.

Contribution

It demonstrates the connection between gelation, percolation, and structural arrest in colloids through a detailed simulation model considering bond lifetime effects.

Findings

Relaxation time follows a power law at low temperatures and volume fractions.

Long-lived clusters are crucial for gelation and percolation.

Bond lifetime influences the deviation from critical behavior.

Abstract

By means of molecular dynamics, we study a model system for colloidal suspensions where the interaction is based on a competition between attraction and repulsion. At low temperatures the relaxation time $\tau$ first increases as a power law as a function of the volume fraction $\phi$ and then, due to the finite lifetime of the bonded structures, it deviates from this critical behavior. We show that colloidal gelation at low temperatures and low volume fractions is crucially related to the formation of spanning long living cluster. Besides agreeing with experimental findings in different colloidal systems, our results shed new light on the different role played by the formation of long living bonds and the crowding of the particles in colloidal structural arrest.