Structural and dynamical properties of gel networks

TL;DR

This paper investigates the formation, structure, and aging dynamics of gel networks in colloid-polymer mixtures using Brownian dynamics simulations, revealing their complex multi-scale properties.

Contribution

It introduces a reduced network analysis method and compares gel network properties to other colloidal states, highlighting their unique structural and dynamical features.

Findings

Gel networks form at low packing fractions with strong attractions.

Structural and dynamical properties vary across length and time scales.

Gel networks exhibit distinct features compared to bulky gels or cluster fluids.

Abstract

The competition of depletion attractions and longer-ranged repulsions between colloidal particles in colloid-polymer mixtures leads to the formation of heterogeneous gel-like structures. For instance, gel networks, i.e., states where the colloids arrange in thin strands that span the whole system occur at low packing fractions for attractions that are stronger than those at the binodal line of equilibrium liquid-fluid phase separation. By using Brownian dynamics simulations we explore the formation, structure, and ageing dynamics of gel networks. We determine reduced network that focus on the essential connections in a gel network. We compare the observed properties to those of bulky gels or cluster fluids. Our results demonstrate that both the structure as well as the (often slow) dynamics of the stable or meta-stable heterogenous states in colloid-polymer mixtures possess distinct features on various length and time scales and thus are richly divers.