Diffusion, phase behavior and gelation in a two-dimensional layer of colloids in osmotic equilibrium with a polymer reservoir

TL;DR

This paper investigates how adding non-adsorbing polymers affects phase behavior and gelation in a two-dimensional colloidal layer, revealing unique gel structures with locally crystalline strands and aligning with prior simulations and theories.

Contribution

It demonstrates that gelation in 2D colloids can produce locally crystalline strands, extending understanding of depletion-induced phenomena in reduced dimensions.

Findings

Gelation involves locally crystalline strands.

Phase behavior resembles 3D crystal-fluid coexistence.

Results agree with previous simulations and theories.

Abstract

The addition of enough non-adsorbing polymer to an otherwise stable colloidal suspension gives rise to a variety of phase behavior and kinetic arrest due to the depletion attraction induced between the colloids by the polymers. We report a study of these phenomena in a two-dimensional layer of colloids. The three-dimensional phenomenology of crystal-fluid coexistence is reproduced, but gelation takes a novel form, in which the strands in the gel structure are locally crystalline. We compare our findings with a previous simulation and theory, and find substantial agreement.