Teflon AF–Coated Nanotextured Aluminum Surfaces for Jumping Droplet Thermal Rectification

Jumping droplet thermal diodes (JDTDs) are promising candidates to achieve thermal rectification for next‐generation thermal control. However, most prior demonstrations of JDTDs have relied on monolayer‐coated copper‐based superhydrophobic (SHPB) surfaces, while lower‐cost aluminum JDTDs with more d...

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Bibliographic Details
Published in:Advanced materials interfaces 2024-05, Vol.11 (13), p.n/a
Main Authors: Shimokusu, Trevor J., Nathani, Alia, Liu, Zhen, Yap, Te Faye, Preston, Daniel J., Wehmeyer, Geoff
Format: Article
Language:English
Subjects:
Aluminum
Droplets
Durability
fluid repellency
Fluoropolymers
heat rectification
Hydrophobicity
Immersion coating
jumping droplet condensation
Monolayers
Polymer coatings
Polytetrafluoroethylene
surface engineering
Temperature profiles
thermal circuits
thermal diodes
Thermal management
Thin films
vapor chambers
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Summary:Jumping droplet thermal diodes (JDTDs) are promising candidates to achieve thermal rectification for next‐generation thermal control. However, most prior demonstrations of JDTDs have relied on monolayer‐coated copper‐based superhydrophobic (SHPB) surfaces, while lower‐cost aluminum JDTDs with more durable thin polymeric coatings have not been explored. In this work, a JDTD is constructed that employs SHPB aluminum surfaces coated with protective thin films of Teflon AF (amorphous fluoropolymer) 1601. Measurements for different heating orientations, gap heights (H), and fill ratios (ϕ) show that a maximum thermal rectification ratio of 7 can be achieved for H  =  2.4 mm and ϕ  =  10%. A thermal circuit is demonstrated that uses the JDTD to rectify time‐periodic temperature profiles, achieving thermal circuit effectiveness values up to 30% of the ideal‐diode limit. Coupon‐level durability tests and device‐level cycling show that dip coated Teflon AF enables stable operation of Al JDTDs over >20 cycles, improving on the performance of a monolayer‐coated surface that fails after 5 cycles. The findings of this work signify that Teflon AF coated Al SHPB surfaces can be used for thermal rectification and motivate future research into Al JDTDs for advanced thermal management applications. Monolayer‐coated superhydrophobic surfaces used in jumping droplet thermal diodes (JDTDs) enable thermal rectification, but degrade upon continuous exposure to condensing water vapor. This study demonstrates that dip coated Teflon AF 1601 films improve the durability of nanotextured aluminum surfaces, enabling prolonged operation and comprehensive thermal testing of an aluminum‐based JDTD.
ISSN:2196-7350
2196-7350
DOI:10.1002/admi.202300817