Strain-Induced Surface Micro/Nanosphere Structure: A New Technique to Design Mechanically Robust Superhydrophobic Surfaces with Rose Petal-Like Morphology

A robust surface geometrical structure not only enables a favorable practical application but also leads to a long-term reliability of superhydrophobic surfaces, and hence it is pivotal to find an effective route to improve the mechanical durability of superhydrophobic surfaces. This study reports a simple magnetron sputtering method to directly construct a robust rose petal-like copper surface with high water adhesion (petal effect). A stable surface micro/nanosphere topography combining with naturally low surface energy is spontaneously formed by the strain-induced-island growth of the copper films during the sputtering process. Further reduced surface energy by fluorosilane, the rose petal-like surface shows a high water contact angle (≈161.4°), effective adhesion force of ≈154 µN, and no-loss transportation critical droplet volume of ≈98 µL. In addition, as-prepared superhydrophobic surfaces exhibit superior mechanical stability according to the thermal shock (−40 °C/90 °C) for ≈500 cycles, water-impacting test for ≈6 h, and finger touch (≈20 times) as well as tape-peeling test (≈65 times) without losing superhydrophobicity. This work might provide a novel but simple way to directly and effectively fabricating robust superhydrophobic metallic surfaces for potential industrial applications, and can be easily extended to other metals and alloys.