Static and dynamic properties of a reversible gel

TL;DR

This study uses computer simulations to explore the static and dynamic behaviors of a realistic model of reversible gels, revealing phase behavior, structural homogeneity, and dynamic heterogeneity at equilibrium.

Contribution

It provides a detailed analysis of the phase diagram and dynamic properties of a microscopically realistic reversible gel model, highlighting differences from glass-formers.

Findings

Gelation causes significant slowing down of dynamics.

The gel's structure is homogeneous with a fractal stress network.

Dynamics are highly heterogeneous due to mobile and arrested particle populations.

Abstract

We study a microscopically realistic model of a physical gel and use computer simulations to investigate its static and dynamic properties at thermal equilibrium. The phase diagram comprises a sol phase, a coexistence region ending at a critical point, a gelation line, and an equilibrium gel phase unrelated to phase separation. The global structure of the gel is homogeneous, but the stress is supported by a fractal network. Gelation results in a dramatic slowing down of the dynamics, which can be used to locate the transition, which otherwise shows no structural signatures. Moreover, the equilibrium gel dynamics is highly heterogeneous as a result of the presence of particle families with different mobilities. An analysis of gel dynamics in terms of mobile and arrested particles allows us to elucidate several differences between the dynamics of equilibrium gels and that of glass-formers.