Droplet Jumping on Superhydrophobic Copper Oxide Nanostructured Surfaces

Condensation has been widely explored because of its importance in numerous applications including water desalination, water harvesting, power generation, and thermal management. Previous studies have shown that the enhancement in condensation heat transfer can be achieved with the engineering of surface wettability by promoting dropwise condensation that has lower thermal resistances than film condensation. In this paper, we explore microscopic-level droplet dynamics using various copper surfaces by employing a simple two-step chemical method. Nanostructured copper surfaces are prepared by a chemical immersion method using alkaline solution and are further functionalized by using dodecanoic acid that provides the hydrophobicity. The wetting properties and corresponding condensation processes are examined using an optical microscope and environmental scanning electron microscope by capturing the real-time phase change process. The measurements confirm that the surface morphology with the largest feature ratio promotes droplet jumping events. The understanding of condensation behaviors associated with nanostructured copper oxide surfaces can provide design rules for efficient surface structures for numerous condensation applications.