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Article
Dropwise Condensation on Multi-scale Bioinspired Metallic Surfaces with Nano-Features
ACS Applied Materials and Interfaces
  • Daniel Orejon, The University of Edinburgh and Kyushu University
  • Alexandros Askounis, Kyushu University and University of East Anglia
  • Yasuyuki Takata, Kyushu University
  • Daniel Attinger, Iowa State University
Document Type
Article
Publication Version
Submitted Manuscript
Publication Date
6-10-2019
DOI
10.1021/acsami.9b06001
Abstract

Non-wetting surfaces engineered from intrinsically hydrophilic metallic materials are promising for self-cleaning, anti-icing and/or condensation heat transfer applications where the durability of the coating is an issue. In this work, we fabricate and study the wetting behaviour and the condensation performance on two metallic non-wetting surfaces with varying number and size of the roughness tiers without further hydrophobic coating procedure. On one hand, the surface resembling a rose petal exhibits a sticky non-wetting behaviour as drops wet the microscopic roughness features with the consequent enhanced drop adhesion, which leads to filmwise condensation. On the other hand, the surface resembling a lotus leaf provides super-repellent non-wetting behaviour prompting the continuous nucleation, growth and departure of spherical drops in a dropwise condensation fashion. On a lotus leaf surface, the third nano-scale roughness tier (created by chemical oxidation) combined with ambience exposure prompts the growth of drops in the Cassie state with the benefit of minimal condensate adhesion. The two different condensation behaviours reported are well supported by a drop surface energy analysis, which accounts for the different wetting performance and the surface structure underneath the condensing drops. Further, we coated the above-mentioned surfaces with polydimethylsiloxane surfaces, which resulted in filmwise condensation due to the smoothening of the different roughness tiers. Continuous dropwise condensation on a hierarchical bioinspired lotus leaf metallic surface without the need for a conformal hydrophobic coating is hence demonstrated, which offers a novel path for the design and manufacture of non-coated metallic super-repellent surfaces for condensation phase change applications, amongst others.

Comments

This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in ACS Applied Materials and Interfaces, copyright © American Chemical Society after peer review. To access the final edited and published work see DOI: 10.1021/acsami.9b06001. Posted with permission.

Copyright Owner
American Chemical Society
Language
en
File Format
application/pdf
Citation Information
Daniel Orejon, Alexandros Askounis, Yasuyuki Takata and Daniel Attinger. "Dropwise Condensation on Multi-scale Bioinspired Metallic Surfaces with Nano-Features" ACS Applied Materials and Interfaces (2019)
Available at: http://works.bepress.com/daniel_attinger/32/