Molecular Dynamics Simulation of nanobubbles in the bulk and on the substrate

Nanobubbles are considered to be one origin of characteristic behaviors of fluids in microscopic systems, such as boundary slip in channels and long-range attractive force acting between hydrophobic surfaces. In many recent experiments, nanobubbles on the hydrophobic substrates are observed with atomic force microscopy , infrared spectroscopy and other techniques. Observed nanobubbles are extraordinarily stable; for instance, Zhang et al. reported that air nanobubbles on hydrophobic walls survive for more than 4 days[1]. However, according to the classical diffusion model based on Young-Laplace equation, nanobubbles cannot be stable because the gas in the bubble diffuses rapidly into the surrounding liquid due to higher pressure in the bubble. The lifetime of the spherical bubble whose radius is 10-100nm, is estimated to be 1-100μs[2], which is at least 9 orders of magnitude shorter than the observed lifetimes.