Explaining Evaporation-Triggered Wetting Transition Using Local Force Balance Model and Contact Line-Fraction
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Author(s)
Annavarapu, Rama Kishore
Sojoudi, Hossein
Kim, Sanha
Hart, Anastasios John
Wang, Minghui
Date Issued
January 2019
Journal
Scientific Reports
Publisher
Nature Publishing Group
Citation
Annavarapu, Rama Kishore, Sanha Kim, Minghui Wang, A. John Hart, and Hossein Sojoudi. “Explaining Evaporation-Triggered Wetting Transition Using Local Force Balance Model and Contact Line-Fraction.” Scientific Reports 9, no. 1 (January 23, 2019). © 2019 The Authors
Version
Final published version
Abstract
Understanding wettability and mechanisms of wetting transition are important for design and engineering of superhydrophobic surfaces. There have been numerous studies on the design and fabrication of superhydrophobic and omniphobic surfaces and on the wetting transition mechanisms triggered by liquid evaporation. However, there is a lack of a universal method to examine wetting transition on rough surfaces. Here, we introduce force zones across the droplet base and use a local force balance model to explain wetting transition on engineered nanoporous microstructures, utilizing a critical force per unit length (FPL) value. For the first time, we provide a universal scale using the concept of the critical FPL value which enables comparison of various superhydrophobic surfaces in terms of preventing wetting transition during liquid evaporation. In addition, we establish the concept of contact line-fraction theoretically and experimentally by relating it to area-fraction, which clarifies various arguments about the validity of the Cassie-Baxter equation. We use the contact line-fraction model to explain the droplet contact angles, liquid evaporation modes, and depinning mechanism during liquid evaporation. Finally, we develop a model relating a droplet curvature to conventional beam deflection, providing a framework for engineering pressure stable superhydrophobic surfaces.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
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Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1038/s41598-018-37093-6
