Wettability versus roughness: Multi-scales approach

These authors experimentally investigate the influence of multi-scale roughness on contact angle measurements, and they propose a model combining the Wenzel and Cassie-Baxter equations with the 3D roughness parameters defined by ISO25178. To do this, a generic methodology based on a statistical method (bootstrap and correlation coefficient) is developed and applied to a polypropylene textured femtosecond laser (55 surfaces, ablation depths=5-45 μm and depth/diameter=0.07-0.53). A mixed model is proposed according to the correlations obtained between the contact angle of a plane surface, θ0, and a textured surface, θ, with the roughness parameters as the developed surface, Sdr, closed hills area, Sha and the closed dales area, Sda, with regard to the models of Wenzel and Cassie-Baxter.