Effect of the polydispersity of a colloidal drop on the drying induced stress as measured by the buckling of a floating sheet

TL;DR

This study investigates how particle size variation in colloidal drops influences drying-induced stress, using buckling of a floating sheet as a measurement method, revealing that larger particles dominate stress behavior.

Contribution

It demonstrates that polydispersity significantly affects drying stress, with larger particles reducing stress and dominating the behavior in polydisperse colloidal suspensions.

Findings

Small number of large particles decreases drying stress.

Stress is dominated by larger particles rather than average size.

Polydispersity influences the formation of stress pathways.

Abstract

We study the stress developed during the drying of a colloidal drop of silica nanoparticles. In particular, we use the wrinkling instability of a thin floating sheet to measure the net stress applied by the deposit on the substrate and we focus on the effect of the particle polydispersity. In the case of a bidisperse suspension, we show that a small number of large particles substantially decreases the expected stress, which we interpret as the formation of lower hydrodynamic resistance paths in the porous material. As colloidal suspensions are usually polydisperse, we show for different average particle sizes that the stress is effectively dominated by the larger particles of the distribution and not by the average particle size.