In 2001 Pascale Aussillous and David Quéré from the Collège de France’s Laboratory of Condensed Matter Physics were able to cover a drop of liquid with hydrophobic particles and fashion a spherical structure they called a liquid marble. Liquid marbles remain stable in atmospheric pressures up to twice their Laplace pressure (the pressure difference between the inside and outside of their curved surface).
Now, along the same lines, Yousra Timounay, Olivier Pitois, and Florence Rouyer at the Université Paris–Est have developed a structure they’re calling a gas marble. The new marbles each consist of a small pocket of gas enclosed in a shell made of tiny polystyrene beads. The beads are linked together by a thin liquid meniscus of surfactant solution (see the figure). Gas marbles can range in diameter from 5 mm to nearly 12 mm.
In tests, the Paris team found that gas marbles were even more pressure resistant than their liquid counterparts. When deflated with a syringe, the gas marbles could withstand external pressures of up to 10 times their Laplace pressure. Crucially, gas marbles also remained stable when their internal pressure increased, unlike liquid marbles. The researchers attribute the superior stability to the fact that gas marbles have two liquid–gas interfaces, while the liquid marbles have only one. They suggest that gas marbles could have applications for the containment and transport of dangerous gases, or lead to new techniques for aerating various materials. (Y. Timounay, O. Pitois, F. Rouyer, Phys. Rev. Lett. 118, 228001, 2017.)
