Quadri-directionally anisotropic droplets sliding surfaces fabricated by selective laser texturing of aluminum alloy plates

• DOI: 10.1016/j.apsusc.2020.145406
• Publication Date: 2020-01-17T00:11:51Z
• Authors: Xikang Zhou; Wei Xue; Wenwen Liu; Dehua Zhu; Yu Cao
• Keywords: 01 natural sciences; 0104 chemical sciences

Abstract A periodic array patterned superhydrophobic surface consisted of asymmetric multi-directional stairway units was prepared by selective laser texturing of aluminum alloy plate, which was endowed for the first time with the quadri-directionally anisotropic droplets sliding characteristic. Through the layer-by-layer subtractive laser ablation procedure, the unique unequal tread depths of the micron-sized stairway-structure in four directions were ingeniously constructed. The achieved surface with an arbitrary desired sliding angle in any of the four directions constructed a transitional superhydrophobic state between Wenzel’s and Cassie’s states of the supported water droplets. The comprehensive mechanism of the supernatural quadri-directional anisotropy was verified to be mainly summarized into the synergy and balance between the droplet’s resistance effect of gravity force and the pinning-effect controlled adhesion force. The two obstructive effects were verified to be in exact accordance with each other on the movement of water droplets. The quadri-directionally anisotropic sliding droplets characteristic induced by the simple but powerful selective laser texturing method can provide a fresh cognition of anisotropic wettability and enormous potential applications in microfluidic systems for biochemical separation.