Journal article
Formation and Stability of Thin Condensing Films on Structured Amphiphilic Surfaces
Langmuir, v 37(8), pp 2683-2692
02 Mar 2021
PMID: 33600180
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
We present a microamphiphilic surface to promote the formation of a thin, stable liquid film during condensation. The surface consists of a hydrophilic micropillar array with hydrophobic pillar tips and was made using photolithography, deep reactive ion etching, and liftoff. The hydrophobic tips prevent the liquid film from growing thick, thereby keeping the thermal resistance low without the cyclical growth and shedding process of dropwise condensation. The wetting behavior was modeled analytically, and the parameters required for film formation were determined and verified with ESEM experiments. When a surface filled with condensate and lacked a low-pressure zone for the water to leave, a rupture event occurred, and a large Wenzel droplet emerged to flood the surface irreversibly. A number of strategies were found to combat rupture events. Tilting the surface vertically and dipping in a liquid pool gave the condensate a low-pressure region and prevented rupture. Irreversible flooding can also be avoided by ensuring that the emerged droplet was a nonwetting, highly mobile Cassie droplet. Parameters for Cassie-stable amphiphilic surfaces were determined analytically, but the high aspect ratios required prevented the manufacture of these surfaces for this study. Instead a hierarchical design was presented that demonstrated emerged Cassie droplets without challenging the manufacturing limits of the microfabrication procedure. This design avoided Wenzel droplet flooding without the need for a designated low-pressure zone. Additionally, sites for Cassie emergence could be engineered by removing a single pillar from the array at a designated location.
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Details
- Title
- Formation and Stability of Thin Condensing Films on Structured Amphiphilic Surfaces
- Creators
- Rebecca L. Winter - Drexel Univ, Dept Mech Engn & Mech, Philadelphia, PA 19063 USAEmre Olceroglu - Boston ScientificZhengtao Chen - Drexel Univ, Dept Chem & Biol Engn, Philadelphia, PA 19063 USAKenneth K. S. Lau - Drexel UniversityMatthew McCarthy - Drexel University
- Publication Details
- Langmuir, v 37(8), pp 2683-2692
- Publisher
- American Chemical Society; Washington, DC
- Number of pages
- 10
- Grant note
- 1511453; 1454407 / National Science Foundation; National Science Foundation (NSF)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemical and Biological Engineering; Mechanical Engineering and Mechanics
- Web of Science ID
- WOS:000626270200015
- Scopus ID
- 2-s2.0-85102059244
- Other Identifier
- 991019168379904721
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- Collaboration types
- Industry collaboration
- Domestic collaboration
- Web of Science research areas
- Chemistry, Multidisciplinary
- Chemistry, Physical
- Materials Science, Multidisciplinary