Microscopic Picture of Cooperative Processes in Restructuring Gel Networks

TL;DR

This paper investigates how local bond breaking in colloidal gel networks influences their global mechanical response, revealing that local restructuring effects propagate over large distances, which explains the need for nonlocal models.

Contribution

The study provides a microscopic understanding of stress transmission in gel networks by linking local bond dynamics to macroscopic behavior through space-resolved analysis and simulations.

Findings

Local bond breaking effects propagate over large distances.

Nonlocal constitutive relations are necessary for accurate modeling.

Microscopic restructuring explains complex gel mechanics.

Abstract

Colloidal gel networks are disordered elastic solids that can form even in extremely dilute particle suspensions. With interaction strengths comparable to the thermal energy, their stress-bearing network can locally restructure via breaking and reforming interparticle bonds. This allows for yielding, self-healing, and adaptive mechanics under deformation. Designing such features requires controlling stress transmission through the complex structure of the gel and this is challenging because the link between local restructuring and overall response of the network is still missing. Here, we use a space resolved analysis of dynamical processes and numerical simulations of a model gel to gain insight into this link. We show that consequences of local bond breaking propagate along the gel network over distances larger than the average mesh size. This provides the missing microscopic explanation for why nonlocal constitutive relations are necessary to rationalize the nontrivial mechanical response of colloidal gels.