Spatial Control of Condensation and Freezing on Superhydrophobic Surfaces with Hydrophilic Patches

Journal Article · Wed Sep 25 04:00:00 EDT 2013 · Advanced Functional Materials (Online)

DOI:https://doi.org/10.1002/adfm.201300418· OSTI ID:1185185

Mishchenko, Lidiya ^[1]; Khan, M. ^[2]; Aizenberg, Joanna ^[2]; Hatton, Benjamin ^[3]

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1. Harvard Univ., Cambridge, MA (United States); Wyss Institute at Harvard
2. Harvard Univ., Cambridge, MA (United States)
3. Univ. of Toronto, ON (Canada)

Certain natural organisms use micro-patterned surface chemistry, or ice-nucleating species, to control water condensation and ice nucleation for survival under extreme conditions. As an analogy to these biological approaches, it is shown that functionalized, hydrophilic polymers and particles deposited on the tips of superhydrophobic posts induce precise topographical control over water condensation and freezing at the micrometer scale. A bottom-up deposition process is used to take advantage of the limited contact area of a non-wetting aqueous solution on a superhydrophobic surface. Hydrophilic polymer deposition on the tips of these geometrical structures allows spatial control over the nucleation, growth, and coalescence of micrometer-scale water droplets. The hydrophilic tips nucleate water droplets with extremely uniform nucleation and growth rates, uniform sizes, an increased stability against coalescence, and asymmetric droplet morphologies. Furthermore, control of freezing behavior is also demonstrated via deposition of ice-nucleating AgI nanoparticles on the tips of these structures. The combination of the hydrophilic polymer and AgI particles on the tips was used to achieve templating of ice nucleation at the micrometer scale. Preliminary results indicate that control over ice crystal size, spatial symmetry, and position might be possible with this method. This type of approach can serve as a platform for systematically analyzing micrometer-scale condensation and freezing phenomena, and as a model for natural systems.

• Research Organization: Harvard Univ., Cambridge, MA (United States). Wyss Institute at Harvard
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: AR0000326
• OSTI ID: 1185185
• Journal Information: Advanced Functional Materials (Online), Journal Name: Advanced Functional Materials (Online) Journal Issue: 36 Vol. 23; ISSN 1616-3028
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
condensation
patterned wettability
post array
superhydrophobic