Direct Imaging of Complex Nano- to Microscale Interfaces Involving Solid, Liquid, and Gas Phases

Konrad Rykaczewski †‡*, Trevan Landin §, Marlon L. Walker ‡, John Henry J. Scott ‡, and Kripa K. Varanasi †*

^† Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States

^‡ Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States

^§ FEI Company, Hillsboro, Oregon 97124, United States

ACS Nano, Article ASAP

DOI: 10.1021/nn304250e

Publication Date (Web): September 28, 2012

Copyright © 2012 American Chemical Society

Surfaces with special wetting properties not only can efficiently repel or attract liquids such as water and oils but also can prevent formation of biofilms, ice, and clathrate hydrates. Predicting the wetting properties of these special surfaces requires detailed knowledge of the composition and geometry of the interfacial region between the droplet and the underlying substrate. In this work we introduce a 3D quantitative method for direct nanoscale visualization of such interfaces. Specifically, we demonstrate direct nano- to microscale imaging of complex fluidic interfaces using cryostabilization in combination with cryogenic focused ion beam milling and SEM imaging. We show that application of this method yields quantitative information about the interfacial geometry of water condensate on superhydrophilic, superhydrophobic, and lubricant-impregnated surfaces with previously unattainable nanoscale resolution. This type of information is crucial to a fundamental understanding as well as the design of surfaces with special wetting properties.