Abstract:
The primary mechanism of rupture of aqueous films on electrically charged solid surfaces is due to attraction between the electrical double layers formed at the solid-liquid and liquid-gas interfaces. When these interfaces have fixed charge densities of the opposite signs, the linear theory predict instability and is usually cited as the explanation of the experimental data on film rupture. We develop a nonlinear lubrication-type model of liquid-gas interface evolution using the same framework and show that the nonlinearity will prevent film rupture for a wide range of conditions. To reconcile the new theoretical results with the experimental evidence of film rupture by the electrostatic forces, we propose the effect of charge regulation at interfaces as the key physical mechanism leading to film rupture. The rupture model is then extended to the case of periodically structured substrates using the Floquet theory.