Wetting process in superhydrophobic disordered surfaces

A sessile (water) drop deposited onto a superhydrophobic surface can stay in two different regimes: the heterogeneous (or Cassie-Baxter) regime, where air or vapour is trapped at the interface, or the homogenous (or Wenzel) regime, where the interface is completely wet. Often, a spontaneous transition from the first to the second regime may occur in time. We report on a study of this phenomenon in a new kind of superhydrophobic surfaces, characterized by a relevant spatial disorder. The observed transition follows a behaviour quite different respect to the one measured in the commonly used periodic artificial arrays.