Self-assembly and cooperative dynamics of a model colloidal gel network

TL;DR

This paper investigates the self-assembly and cooperative dynamics of colloidal gel networks, revealing how local rigidity and network topology influence particle localization and restructuring through bond dynamics.

Contribution

It introduces a theoretical and simulation-based analysis of gel network formation, emphasizing the role of mesoscale organization in cooperative restructuring dynamics.

Findings

Network formation follows Flory-Huggins theory until chain networks develop.

Particle localization is influenced by network topology, similar to caging in glasses.

Restructuring dynamics are highly cooperative and consistent across simulation methods.

Abstract

We study the assembly into a gel network of colloidal particles, via effective interactions that yield local rigidity and make dilute network structures mechanically stable. The self-assembly process can be described by a Flory-Huggins theory, until a network of chains forms, whose mesh size is on the order of, or smaller than, the persistence length of the chains. The localization of the particles in the network, akin to some extent to caging in dense glasses, is determined by the network topology, and the network restructuring, which takes place via bond breaking and recombination, is characterized by highly cooperative dynamics. We use NVE and NVT Molecular Dynamics as well as Langevin Dynamics and find a qualitatively similar time dependence of time correlations and of the dynamical susceptibility of the restructuring gel. This confirms that the cooperative dynamics emerge from the mesoscale organization of the network.