Interaction anisotropy and the KPZ to KPZQ transition in particle deposition at the edges of drying drops

TL;DR

This study investigates how particle shape and interaction anisotropy influence deposit patterns at evaporating drop edges, revealing a transition from KPZ to KPZQ universality classes driven by anisotropic interactions.

Contribution

The paper introduces a numerical model linking particle interaction anisotropy to the KPZ to KPZQ transition in deposit growth, supported by experimental validation.

Findings

Deposit density decreases with increasing particle aspect ratio.

Transition from KPZ to KPZQ universality class occurs due to interaction anisotropy.

Numerical results align with experimental observations.

Abstract

The deposition process at the edge of evaporating colloidal drops varies with the shape of suspended particles. Experiments with prolate ellipsoidal particles suggest that the spatiotemporal properties of the deposit depend strongly on particle aspect ratio. As the aspect ratio increases, the particles form less densely-packed deposits and the statistical behavior of the deposit interface crosses over from the Kardar-Parisi-Zhang (KPZ) universality class to another universality class which was suggested to be consistent with the KPZ plus quenched disorder. Here, we numerically study the effect of particle interaction anisotropy on deposit growth. In essence, we model the ellipsoids, at the interface, as disk-like particles with two types of interaction patches that correspond to specific features at the poles and equator of the ellipsoid. The numerical results corroborate experimental observations and further suggest that the deposition transition can stem from interparticle interaction anisotropy. Possible extensions of our model to other systems are also discussed.