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.

Details

Title
Explaining Evaporation-Triggered Wetting Transition Using Local Force Balance Model and Contact Line-Fraction
Author
Annavarapu Rama Kishore 1 ; Kim Sanha 2 ; Wang, Minghui 3   VIAFID ORCID Logo  ; John, Hart A 2   VIAFID ORCID Logo  ; Sojoudi Hossein 1   VIAFID ORCID Logo 

 The University of Toledo, Department of Mechanical, Industrial, and Manufacturing Engineering (MIME), Toledo, United States (GRID:grid.267337.4) (ISNI:0000 0001 2184 944X) 
 Massachusetts Institute of Technology (MIT), Department of Mechanical Engineering, Cambridge, United States (GRID:grid.116068.8) (ISNI:0000 0001 2341 2786) 
 Massachusetts Institute of Technology (MIT), Department of Chemical Engineering, Cambridge, United States (GRID:grid.116068.8) (ISNI:0000 0001 2341 2786) 
Publication year
2019
Publication date
Jan 2019
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2170385684
Copyright
This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.