Dynamic stratification in drying films of colloidal mixtures

TL;DR

This paper investigates how mixtures of different-sized colloidal particles in water undergo stratification during drying, revealing that osmotic pressure gradients drive the segregation process.

Contribution

The study introduces a model linking osmotic pressure gradients to stratification, providing new insights into the drying behavior of colloidal mixtures.

Findings

Stratification occurs with larger particles at the bottom and smaller on top.

Osmotic pressure gradients are key to the segregation mechanism.

The model explains the dynamic development of stratification during drying.

Abstract

In simulations and experiments, we study the drying of films containing mixtures of large and small colloidal particles in water. During drying, the mixture stratifies into a layer of the larger particles at the bottom with a layer of the smaller particles on top. We developed a model to show that a gradient in osmotic pressure, which develops dynamically during drying, is responsible for the segregation mechanism behind stratification.