Heterogeneous diffusion in a reversible gel

TL;DR

This paper presents a realistic microscopic model of a physical gel, exploring its static and dynamic properties through simulations, revealing a complex phase diagram and heterogeneous dynamics distinct from glass-formers.

Contribution

It introduces a new simulation-based model of a physical gel with detailed phase behavior and a theoretical framework for understanding dynamic heterogeneity.

Findings

Identifies a complex phase diagram with sol, coexistence, and gel phases.

Shows the gel's structure is homogeneous but stress is supported by a fractal network.

Proposes a theoretical model for dynamic heterogeneity in gels.

Abstract

We introduce a microscopically realistic model of a physical gel and use computer simulations to study 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 determined by geometric percolation, 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. The gel dynamics is highly heterogeneous and we propose a theoretical model to quantitatively describe dynamic heterogeneity in gels. We elucidate several differences between the dynamics of gels and that of glass-formers.