Mapping Of Heterogeneous Wetting Inside Superhydrophobic Coatings

Abstract

The condition for the occurrence of induced drying inside structured coating was calculated and corresponds to a new format of the Kelvin equation. Water spatial distribution inside immersed interconnected fibers forming superhydrophobic coatings was then imaged by confocal Raman microscopy characterizing the heterogeneous wetting profile. Coatings were structurally characterized by scanning electron microscopy (resolution similar to 0.1 mu m) and interconnected fiber structure lateral area and empty volume (V-emp) measured. The combination of these micrograph images yield a new measurement technique readily applied for structurally characterizing immersed coating hydrophobicity. When this technique was applied for coatings showing induced drying, the measured coating layer lateral area per unit volume was similar to 10(4)/m, which differs by two orders of magnitude with the value calculated by the Kelvin equation. (C) 2016 Elsevier B.V. All rights reserved.