Gravity-induced double encapsulation of liquids using granular rafts

Abstract

In this study, we experimentally reveal the liquid-like and solid-like behaviors of millimetric liquid marbles when they sediment in oil towards a water layer below. Upon dynamically interacting with the oil-water interface, an aqueous armored droplet is shown to either rupture or remain intact as the oil surrounding the drop pinches off. The pinch-off in the novel gravity-driven regime leads to the double-encapsulation of aqueous solutions, which enables their secure transport in a wet environment. We also present scaling laws that account for the drop's weight and the oil viscosities, in good agreement with the experiments.