Surfactant Driven Fracture of Interfacial Particle Rafts

TL;DR

This study explores how surfactant-induced Marangoni flows control the dynamic fracture of particle rafts at liquid interfaces, revealing non-elastic factors dominate crack propagation speed and scaling behavior.

Contribution

It demonstrates that surfactant advection, not elasticity, governs crack speed in particle rafts, introducing a new perspective on interfacial fracture mechanics.

Findings

Crack speed is unaffected by raft elasticity.

Surfactant advection controls crack propagation.

Crack length scales as t^{3/4}."

Abstract

We investigate the dynamic fracture of a close-packed monolayer of particles, or particle raft, floating at a liquid-gas interface induced by the localised addition of surfactant. Unusually for a two-dimensional solid, our experiments show that the speed of crack propagation here is not affected by the elastic properties of the raft. Instead it is controlled by the rate at which surfactant is advected to the crack tip by means of the induced Marangoni flows. Further, the velocity of propagation is not constant in time and the length of the crack scales as $t^{3/4}$. More broadly, this surfactant induced rupture of interfacial rafts suggests ways to manipulate them for applications.