Wetting of soap bubbles on soft elastomers with surface stress and gravity

Abstract

Surface stress and gravitational force have significant effects on the deformation of soft elastomers. By considering surface stress and gravity of the soft elastomer, we study wetting behaviors of soap bubbles on a semi-space elastomer through the surface Green’s function method. The normal surface displacement of the elastomer caused by the surface tension and Laplace pressure is calculated. The normal surface displacement in the contact zone monotonously increases from the center to the triple line, and the contact zone is divided into concave zone and convex zone. The results show that surface stress and gravity have significant influence on the normal surface deformation caused by the wetting of the soap bubble. In general, surface stress and gravity suppress the amplitude of the normal surface displacement. With the increase of surface stress, the amplitude of the normal surface displacement in the concave and convex zones decreases. However, with the increase of gravity, the amplitude of the normal surface displacement in the concave zone decreases, while that in the convex zone increases. This counterintuitive phenomenon can be understood by the superimposition of displacements. The results have potential applications in the fields of adhesion, indentation, evaporation, cell migration on soft materials, etc.