Experimental and theoretical evaluation of wettability on microano hierarchically engineered surfaces based on robust micro-post-arrayed- and highly ordered nano-rippled-structures

摘要

This paper reports a simple approach for demonstrating a microano hierarchical surface, ensuring both geometrical regularity and mechanical stability, for improving the hydrophobicity. The proposed dual-scale hierarchical surfaces were realized simply by combining the highly self-ordered ripple-like nano patterns with the robust micro-post arrays, based on the cost-effective nonlithographic chemical oxidation process and well-established microfabrication technologies. The wettability of the proposed nano-scale mono- and microano dual-roughened surfaces was evaluated by measuring the apparent contact angles (ACAs), and analyzed theoretically with analytic models based on the Wenzel, Cassie, and combined wetting theories. Through experimental and theoretical observations, it was found that the proposed microano hierarchical structures can improve the wetting property and the superhydrophobic robustness of high- and low-density micro-post arrayed surfaces, respectively.