Universal scaling of nanoparticle deposition by colloidal droplet drying

TL;DR

This study investigates nanoparticle deposition patterns during colloidal droplet drying, revealing a universal scaling law governed by the competition between capillary flow and diffusion, enabling pattern prediction from material properties.

Contribution

The paper introduces a unified framework linking deposition patterns to a Péclet number, supported by modeling and analysis, to predict final patterns based solely on material properties.

Findings

Deposition patterns depend linearly on an effective Péclet number.

Final patterns can be predicted from material properties.

Multiple complex patterns are explained by the model.

Abstract

We present a comprehensive study of nanoparticle deposition from drying of colloidal droplets. By means of lattice Boltzmann modeling and theoretical analysis, various deposition patterns, including mountain-like, uniform and coffee ring, as well as un-/symmetrical multiring/mountain-like patterns are achieved. The ratio of nanoparticles deposited at droplet peripheries and center is proposed to quantify different patterns. Its value is controlled by the competition between the capillary flow and nanoparticle diffusion, leading to a linear dependence on an effective P\'eclet number, across over three orders of magnitude. Remarkably, the final deposition pattern can be predicted based on material properties only.