When coated with microscale hydrophobic particles, macroscopic liquid droplets can become non-wetting liquid marbles that exhibit many fascinating solid-like properties. Specifically, the force required to uniaxially compress liquid marbles depends on their volume, but it is unclear if the particle coating plays a role. In contrast, failure of marbles upon compression does depend on the particle coating, but the conditions for failure do not appear to change with marble volume. Here, we experimentally study the elastic deformation and failure of liquid marbles and, by applying a doubly truncated oblate spheroid model to quantify their surface area, explore the role of marble volume and particle composition. First, we find that the work required to compress liquid marbles agrees with the product of the fluid surface tension and the change in surface area, validating that the elastic mechanics of marbles is independent of the particle coating. Next, we study marble failure by measuring their ductility as quantified by the maximum fractional increase in marble surface area prior to rupture. Not only does marble ductility depend on the particle coating, it also depends on the volume with smaller marbles being more ductile. This size effect is attributed to an interaction between marble curvature and particle rafts held together by interparticle forces. Building on these results, we seek to better understand the role of interparticle interactions on marble ductility by conducting microscopic and macroscopic experiments using particles with tunable shape and interactions. In particular, macroscopic experiments were performed on particle-laden interfaces in which the interaction forces of the particles can be tuned from weakly to strongly interactive. These experiments elucidate the analogy between ductility and the macroscopic behavior of particle-laden interfaces. Tailoring the strength of these interactions is essential for realizing controlled rupture of liquid marbles for applications ranging from smart fluid handling to pollution mitigation.

Elasticity and failure of liquid marbles: Influence of particle coating and marble volume

256th National Meeting (2018)

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