Interfacial Polygonal Nanopatterning of Stable Microbubbles
Emilie Dressaire,1
Rodney Bee,2
David C. Bell,1
Alex Lips,2
Howard A. Stone1*
Micrometer-sized bubbles are unstable and therefore difficult to make and store for substantial lengths of time. Short-term stabilization is achieved by the addition of amphiphilic molecules, which reduce the driving force for dissolution. When these molecules crystallize on the air/liquid interface, the lifetime of individual bubbles may extend over a few months. We demonstrated low gas-fraction dispersions with mean bubble radii of less than 1 micrometer and stability lasting more than a year. An insoluble, self-assembled surfactant layer covers the surface of the microbubbles, which can result in nanometer-scale hexagonal patterning that we explain with thermodynamic and molecular models. The elastic response of the interface arrests the shrinkage of the bubbles. Our study identifies a route to fabricate highly stable dispersions of microbubbles.
1 School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
2 Unilever Research and Development, 40 Merritt Boulevard, Trumbull, CT 06611, USA.
* To whom correspondence should be addressed. E-mail: has{at}seas.harvard.edu
