Mechanical stretch for tunable wetting from topological PDMS film

Abstract

In this paper, we report a mechanical stretch method for tunable wetting from elastic topologically grooved poly(dimethysiloxane) films. The mechanical strain was applied to elongate the film along two orthogonal directions, perpendicular and parallel to the grooves. Along with the increase of mechanical strain, the primary anisotropic wetting of the films was turned into isotropic or a larger degree of anisotropy depending on the stretching direction. The roughness factor as well as the energetic barrier are responsible for the wetting tuning. Effects of the height and period on tunable wetting were investigated, and multiple-cycle reversible switching between anisotropic and isotropic many times was achieved.