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

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 platformmore » for systematically analyzing micrometer-scale condensation and freezing phenomena, and as a model for natural systems.« less
 [1] ;  [1] ;  [1] ;  [2]
  1. Harvard Univ., Cambridge, MA (United States)
  2. Univ. of Toronto, ON (Canada)
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Advanced Functional Materials (Online); Journal Volume: 23; Journal Issue: 36
Research Org:
Harvard Univ., Cambridge, MA (United States). Wyss Institute at Harvard
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
36 MATERIALS SCIENCE condensation; post array; patterned wettability; superhydrophobic