Liquid marbles – drops that don’t splash
In 2001 two French scientists, Pascale Aussillous and David Quéré, discovered that coating a water drop with lycopodium powder gives it strange properties. The coated drop rolls and bounces over surfaces without losing any liquid. They called these weird drops “liquid marbles”. The particles in lycopodium powder are “hydrophobic”, meaning they are poorly wet by water. They sit so far out from the water, that they form a barrier between the water and the outside world. Liquid marbles are bizarre materials. They roll like glass beads due to their hard particle shells. Their shape changes as they bounce, however, due to their soft liquid cores. The presence of the particle shell lowers the temperature at which the liquid inside freezes. They do not have to be made from water and hydrophobic powder. At the Ian Wark Research Institute, Rossen Sedev and I investigated liquid marble formation from a range of aqueous and organic liquids. Our research showed how the particle wettability (the extent to which a liquid wets the particles) determines what happens when a liquid drop is mixed with powder. Our findings help people designing liquid marbles choose the best combination of powder and liquid. You can read more about liquid marbles at the Nature’s Raincoats website and in our publication in the journal Soft Matter.
Image Credits:
1. © Advanced Polymer Materials Lab. Osaka Institute of Technology, 2011
2. © Nature’s Raincoats 2009.
3. Reprinted with permission from “Liquid marbles” by Pascale Aussillous and David Quéré in Nature, volume 411, page 924, 2001. Copyright 2001 Nature Publishing Group.
Guest article written by Catherine P. Whitby
