Cluster structure and dynamics in gels and glasses

TL;DR

This paper reviews how structural and dynamical heterogeneities characterize gel and glass transitions, highlighting the clear structural signatures in gels and exploring potential links in glasses through simulations.

Contribution

It provides a comparative analysis of gel and glass transitions, emphasizing the role of dynamical heterogeneities and proposing a connection between glass relaxation and reverse percolation.

Findings

Structural phase transition in gels leads to spanning clusters.

Dynamical heterogeneities are present in both gels and glasses.

Glass relaxation may relate to a reverse percolation transition.

Abstract

The dynamical arrest of gels is the consequence of a well defined structural phase transition, leading to the formation of a spanning cluster of bonded particles. The dynamical glass transition, instead, is not accompanied by any clear structural signature. Nevertheless, both transitions are characterized by the emergence of dynamical heterogeneities. Reviewing recent results from numerical simulations, we discuss the behavior of dynamical heterogeneities in different systems and show that a clear connection with the structure exists in the case of gels. The emerging picture may be also relevant for the more elusive case of glasses. We show, as an example, that the relaxation process of a simple glass-forming model can be related to a reverse percolation transition and discuss further perspective in this direction.