Elasticity of an interfacial particle raft

TL;DR

This paper investigates the elastic properties of a particle monolayer at a fluid interface, demonstrating its solid-like behavior and quantifying its elasticity through theoretical and experimental methods.

Contribution

It introduces a theoretical framework for the elastic moduli of particle rafts and validates it with experimental buckling assays.

Findings

Particle rafts behave as two-dimensional elastic solids.

Theoretical estimates of Young's modulus and Poisson ratio are validated experimentally.

The particle raft can support anisotropic stresses and undergo buckling and cracking.

Abstract

We study the collective behaviour of a close packed monolayer of non-Brownian particles at a fluid-liquid interface. Such a particle raft forms a two-dimensional elastic solid and can support anisotropic stresses and strains, e.g. it buckles in uniaxial compression and cracks in tension. We characterise this solid in terms of a Young's modulus and Poisson ratio derived from simple theoretical considerations and show the validity of these estimates by using an experimental buckling assay to deduce the Young's modulus.