A non equilibrium mechanism for nanobubble stabilization

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Dynamic equilibrium Method for Surface Nanobubble Stabilization

M P Brenner and D Lohse

Phys. Rev. Lett. 101, 214505 (2008)

Keywords: nanobubble, diffusion, Laplace pressure

Summary

A variety of recent studies has demonstrated of nano-scale bubbles of air on the surface of hydrophobic surfaces. Based on the Laplace pressure alone, these bubbles should dissolve rapidly, but yet they are observed over the course of several houra. Previous theories to account for this include: a reduction in surface tension at small length scales, oversaturation of gas in the liquid near the bubble surface, stabilization due to contaminants in the liquid, and induced charges around the bubble interface. The authors propose how the outflow of gas from the surface into the liquid is balanced by uptake of gas around the perimeter.

Soft matter aspects

This paper touches on one of the central themes of the course: how the dynamics at a three-phase interface (i.e. surface, liquid, and gas) can determine the behavior of a system. In this case, the authors are studying the presence of nanobubbles at a surface. The outward pressure of the bubbles is calculated from the radius of curvature. In a typical example, the radius R = 50 nm and the contact angle <math>\theta</math> = 10 degrees or a radius of curvature of 250 nm. . Given a surface tension of 73 mN/m (at 20 C), this corresponds to a pressure of <math>2 \gamma/R = 0.58 MPa</math>.

- Naveen Sinha