Real Space Analysis of Colloidal Gels: Triumphs, Challenges and Future Directions

TL;DR

This review discusses recent advances in real space analysis of colloidal gels, highlighting experimental challenges, particle-level mechanisms of rigidity, and complex behaviors such as ageing and deformation in these materials.

Contribution

It provides a comprehensive overview of particle-resolved studies and real space analysis techniques applied to colloidal gels, emphasizing new insights into their time-dependent behaviors and complex systems.

Findings

Real space analysis reveals particle-level mechanisms of gel rigidity.

Time-dependent behaviors like ageing are captured by simple models.

Experimental challenges include matching refractive index and density.

Abstract

Colloidal gels constitute an important class of materials found in many contexts and with a wide range of applications. Yet as matter far from equilibrium, gels exhibit a variety of time-dependent behaviours, which can be perplexing, such as an increase in strength prior to catastrophic failure. Remarkably, such complex phenomena are faithfully captured by an extremely simple model - "sticky spheres". Here we review progress in our understanding of colloidal gels made through the use of real space analysis and particle resolved studies. We consider the challenges of obtaining a suitable experimental system where the refractive index and density of the colloidal particles is matched to that of the solvent. We review work to obtain a particle-level mechanism for rigidity in gels and the evolution of our understanding of time-dependent behaviour, from early-time aggregation to ageing, before considering the response of colloidal gels to deformation and then move on to more complex systems of anisotropic particles and mixtures. Finally we note some more exotic materials with similar properties.