Mixtures of functionalized colloids on substrates

TL;DR

This study investigates the irreversible aggregation behavior of patchy colloids on substrates, comparing diffusion and advection mechanisms, revealing optimal compositions and density trends linked to phase diagram features.

Contribution

It provides new insights into the kinetics of self-organization of functionalized colloids under different transport mechanisms, extending understanding beyond equilibrium phase diagrams.

Findings

Optimal fraction of two-patch particles maximizes aggregate density in diffusion.

Density decreases monotonically with two-patch fraction under advection.

Aggregation behavior correlates with liquid density on the phase diagram spinodal.

Abstract

Patchy particles are a class of colloids with functionalized surfaces. Through surface functionalization, the strength and directionality of the colloidal interactions are tunable allowing control over coordination of the particle. Exquisite equilibrium phase diagrams of mixtures of coordination two and three have been reported. However, the kinetics of self-organization and the feasibility of the predicted structures are still largely unexplored. Here, we study the irreversible aggregation of these mixtures on a substrate, for different fractions of two-patch particles. Two mechanisms of mass transport are compared: diffusion and advection. In the diffusive case, an optimal fraction is found that maximizes the density of the aggregate. By contrast, for advective transport, the density decreases monotonically with the fraction of two-patch colloids, in line with the behavior of the liquid density on the spinodal of the equilibrium phase diagram.