Metastable States and Wetting Transition of Submerged Superhydrophobic Structures

Abstract

Superhydrophobicity on structured surfaces is frequently achieved via the maintenance of liquid-air interfaces adjacent to the trapped air pockets. These interfaces, however, are subject to instabilities due to the Cassie-Baxter-to-Wenzel transition and total wetting. The current work examines in situ liquid-air interfaces on a submerged surface patterned with cylindrical micropores using confocal microscopy. Both the pinned Cassie-Baxter and depinned metastable states are directly observed and measured. The metastable state dynamically evolves, leading to a transition to the Wenzel state. This process is extensively quantified under different ambient pressure conditions, and the data are in good agreement with a diffusion-based model prediction. A similarity law along with a characteristic time scale is derived which governs the lifetime of the air pockets and which can be used to predict the longevity of underwater superhydrophobicity.

Received 30 December 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.196101

Authors & Affiliations

Pengyu Lv¹, Yahui Xue¹, Yipeng Shi^1,2, Hao Lin^3,*, and Huiling Duan^1,2,†

¹State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China
²Key Laboratory of High Energy Density Physics Simulation, Center for Applied Physics and Technology, Peking University, Beijing 100871, China
³Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA

^*Corresponding author. hlin@jove.rutgers.edu
^†Corresponding author. hlduan@pku.edu.cn

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Physical Review Letters