Condensation Induced Delamination of Nanoscale Hydrophobic Films

Vapor condensation is a crucial phenomenon governing the efficiency of many processes. In particular, dropwise condensation on hydrophobic thin films (≈100 nm‐thick) has the potential to achieve remarkable heat transfer. However, the lack of durability of these thin films has limited applications fo...

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Bibliographic Details
Published in:Advanced functional materials 2019-10, Vol.29 (43), p.n/a
Main Authors: Ma, Jingcheng, Cha, Hyeongyun, Kim, Moon‐Kyung, Cahill, David G., Miljkovic, Nenad
Format: Article
Language:English
Subjects:
blister
Blistering
Blisters
Capillary pressure
Condensation
Delamination
droplets
Durability
failure
Fluorination
hydrophobic
Hydrophobicity
Materials science
Nanoindentation
Pinholes
Polymer films
Thick films
Thin films
Vapors
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Summary:Vapor condensation is a crucial phenomenon governing the efficiency of many processes. In particular, dropwise condensation on hydrophobic thin films (≈100 nm‐thick) has the potential to achieve remarkable heat transfer. However, the lack of durability of these thin films has limited applications for a century. Although degradation due to steam condensation has been described as “blistering,” no satisfactory insight exists capable of elucidating the driving force for film delamination. Here, it is shown that nanoscale pinholes in hydrophobic films are the source of blister formation. By creating artificial pinholes via nanoindentation on thin (30 to 500 nm‐thick) fluorinated hydrophobic films, it is demostrated that water blisters can be initiated at the pinholes during condensation. It is experimentally demonstrated that vapor is transferred to the blister through the nanoscale pinhole, and the driving force for delamination is capillary pressure generated at the pinhole by the pinned liquid–vapor interface. The techniques and insights presented here will inform future work on polymeric thin film and enable their durable design for a variety of applications. Nanoscale pinholes in hydrophobic films govern blister formation and long‐term degradation during water vapor condensation. The outcomes of this work provide guidelines for creating robust hydrophobic films for a plethora of applications, especially stable dropwise condensation.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.201905222