Recently, Dr. Huiling Duan’s group from Department of Mechanics and Engineering Science, College of Engineering, made important progress in wetting transition on micro-structured surfaces, in collaboration with Dr. Hao Lin from Rutgers, The State University of New Jersey. The research paper has been published in Physical Review Letters(Metastable States and Wetting Transition of Submerged Superhydrophobic Structures, Phys. Rev. Lett. 112, 196101, 2014. http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.196101).
Structured superhydrophobic surfaces have attracted a lot of attention because of their broad applications in both engineering and sciences such as slip boundary condition, drag reduction, and flow regulation. One key mechanism to realize their functionality is to maintain on such surfaces a large area fraction of liquid-gas interfaces in the pinned Cassie-Baxter (CB) state. These interfaces, however, are subject to instabilities induced by mechanisms including vibration, evaporation, air diffusion, and impact, which are known to collapse the meniscus, leading to the fully wetted Wenzel (W) state and the failure of the surfaces in performing particular functions, e.g., drag reduction. Understanding the CB-W transition and the dynamic evolution of the metastable state is critical for the regulation and improvement of CB-based superhydrophobicity. For example, structural design can be pursued to maximize the life span of the metastable state such as to extend the longevity of the superhydrophobic functionality.