Role of Surface Topography in the Superhydrophobic Effect—Experimental and Numerical Studies

Abstract

Within these studies, the effect of surface topography for hydrophobic coatings was studieboth numerically and experimentally. Chemically modified polyurethane coating was patterned bapplication of a laser beam. A set of patterns with variously distant linear peaks and grooves waobtained. The cross section of the pattern showed that the edges of the peaks and grooves wernot sharp, instead forming a rounded, rectangle-like shape. For such surfaces, experimental studiewere performed, and in particular the static contact angle (SCA), contact angle hysteresis (CAH), anroll-off angle (ROA) were measured. Profilometry was used to create a numerical representation othe surface. Finite volume method was then applied to simulate the behavior of the water dropletThe model developed herewith enabled us to reproduce the experimental results with good accuracBased on the verified model, the calculation was extended to study the behavior of the water dropleon the simulated patterns, both spiked and rectangular. These two cases, despite a similar SCA of thwater droplet, have shown extremely different ROA. Thus, more detailed studies were dedicated tother geometrical features of such topography, such as the size and distance of the surface elementBased on the results obtained herewith, the future design of superhydrophobic and/or icephobitopography is discussed.