Thin Liquid Film Drainage between an Air Bubble and a Mica Surface with Wettability Contrast

Surfaces with wettability contrast are common in nature, and their interactions with bubbles are essential in many industrial applications. In this study, the interaction between an air bubble and a mica surface with wettability contrast in water is studied by characterizing the thin liquid film drainage between them. Although the mica surface with wettability contrast is asymmetric, the liquid film drainage is still axisymmetric, which is similar to the drainage between a bubble and a solid surface with homogeneous wettability. The dynamics of drainage process for surfaces with wettability contrast can be well captured by the Stokes-Reynolds-Young-Laplace (SRYL) model, expanding the scope of the application of SRYL model from homogeneous surfaces to smooth surfaces with wettability contrast. Subsequent to the axisymmetric drainage process, asymmetric rupture of the thin liquid film happens due to the wettability contrast of the surface. At the final stage of the film rupture, the unbalanced surface tension force originating from the wettability contrast is able to drag the bubble toward the more hydrophobic part of the mica surface when it is large enough to overcome the friction force.