Microscopic contact line dynamics dictate the emergent behaviors of particle rafts
Phys. Rev. Fluids 10, 084003 – Published 20 August, 2025
DOI: https://doi.org/10.1103/ld9n-ctdh
Abstract
Fluid-fluid interfaces laden with discrete particles behave curiously like continuous elastic sheets, leading to their applications in emulsion and foam stabilization. Although existing continuum models can qualitatively capture the elastic buckling of these particle-laden interfaces, often referred to as particle rafts, under compression, they fail to link their macroscopic collective properties to the microscopic behaviors of individual particles. Thus, phenomena such as particle expulsion from the compressed rafts remain unexplained. Here, by combining systematic experiments with first-principle modeling, we reveal how the macroscopic mechanical properties of particle rafts emerge from particle-scale interactions. We construct a phase diagram that delineates the conditions under which a particle raft collapses via collective folding versus single-particle expulsion. Guided by this theoretical framework, we demonstrate control over the raft's failure mode by tuning the physicochemical properties of individual particles. Our study highlights the dual nature of particle rafts and exemplifies how collective dynamics can arise from discrete components with simple interactions.
