How Surface Roughness Affects the Interparticle Interactions at a Liquid Interface

TL;DR

This study investigates how surface roughness influences interparticle interactions at liquid interfaces, revealing complex states and mechanical behaviors that differ from smooth colloids, through experimental and numerical analysis.

Contribution

It introduces a combined experimental and numerical approach to understand how surface roughness affects colloid interactions and jamming at liquid interfaces, highlighting new phenomena.

Findings

Roughness induces a non-trivial intermediate state between gas-like and jammed states.

Roughness reduces the jamming point due to increased friction.

Surface asperities cause off-plane collapse during compression.

Abstract

Shapes of colloids matter at liquid interfaces. We explore the interactions between rough-surfaced nanocolloids at the air--water interface through the compaction of monolayers experimentally and numerically. Sufficiently rough systems exhibit a non-trivial intermediate state between a gas-like state and a close-packed jamming state due to roughness-induced capillary attraction. We also find that roughness-induced friction lowers the jamming point, and the tangential contact force owing to surface asperities can cause a gradual off-plane collapse of the compressed monolayer.