Water Repellency on a Fluorine-Containing Polyurethane Surface: Toward Understanding the Surface Self-Cleaning Effect

Surface geometrical microstructure and low surface free energy are the two most important factors for a self-cleaning surface. In this study, multiform geometrical microstructured surfaces were fabricated by casting and electrospinning polyurethanes with and without low surface energy segments. The effect of low surface energy on water repellency was evaluated. Low surface energy seems to make a more significant contribution to the static wetting, behavior than do dynamic properties such as the improvement of sliding behavior. Sucking disk behavior was brought forward to explain the pinning state of a water droplet on hydrophobic surfaces with high water contact angles (> 150 degrees). A better understanding of the relationship between the static contact angle and the dynamic sliding property was provided.