Model for reversible colloidal gelation

TL;DR

This study uses numerical simulations to explore how limiting the number of bonds in particles affects gel formation and phase behavior, revealing low-density gel states with unique structural and dynamical properties.

Contribution

It introduces a model with a maximum number of bonds per particle, showing how this constraint influences phase separation and enables the study of low-density gel states.

Findings

Liquid-gas coexistence region shrinks for $n_{max}<6$

Low-density gel states exhibit distinct structure and dynamics

Dynamical slowing down occurs without phase separation

Abstract

We report a numerical study, covering a wide range of packing fraction $\phi$ and temperature $T$, for a system of particles interacting via a square well potential supplemented by an additional constraint on the maximum number $n_{\rm max}$ of bonded interactions. We show that when $n_{\rm max}<6$, the liquid-gas coexistence region shrinks, giving access to regions of low $\phi$ where dynamics can be followed down to low $T$ without an intervening phase separation. We characterize these arrested states at low densities (gel states) in terms of structure and dynamical slowing down, pointing out features which are very different from the standard glassy states observed at high $\phi$ values.