Adsorption layer and flow within liquid meniscus in forced dewetting

Abstract

In surfactant solutions, the bulk hydrodynamic flow couples to extensional/compressional surface flows due to Marangoni stresses induced at the interface. With the increasing surfactant concentration, these Marangoni stresses can suppress the surface flows and lead to non-moving, retarded, surfaces. We review this phenomenon with special focus on the dynamic dewetting of a substrate pulled out of a pool of surfactant solution. In this case, the dewetting meniscus surface can be retarded (fully or partially) because of the appearance of surface tension gradients opposing the flow in the adjacent liquid. With an increasing flow velocity, the non-uniformity of the meniscus surface becomes stronger resulting in its separation on a mobile and an immobile part with a sharp transition between them. The presence of a non-uniform adsorption layer at the meniscus surface strongly complicates the dewetting dynamics which becomes dependent on the surfactant balance at the surface.