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Published on: August 15, 2018
Dynamic air layer on textured superhydrophobic surfaces.
Ivan U Vakarelski1, Derek Y C Chan, Jeremy O Marston
1Division of Physical Sciences and Engineering and Clean Combustion Research Centre, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia. ivanuriev.vakarelski@kaust.edu.sa
Langmuir : the ACS Journal of Surfaces and Colloids
|August 8, 2013
Summary
Researchers demonstrated a sustained air plastron on superhydrophobic surfaces in supersaturated water. This dynamic air layer offers a new intermediate state between Leidenfrost and Cassie-Baxter wetting states.
Area of Science:
- Surface science
- Fluid dynamics
- Materials science
Background:
- Superhydrophobic surfaces can trap air, creating a plastron, which is a stable layer of gas between a liquid and a solid.
- The Leidenfrost effect describes a vapor layer forming under a liquid droplet on a surface that is much hotter than the liquid's boiling point.
- The Cassie-Baxter state is a non-wetting state where a liquid is supported by the asperities of a textured surface, trapping air pockets.
Purpose of the Study:
- To experimentally demonstrate the indefinite sustainment of a novel macroscopic, dynamic continuous air layer (plastron) on textured superhydrophobic surfaces in air-supersaturated water.
- To characterize this plastron as an intermediate state between Leidenfrost vapor layers and the equilibrium Cassie-Baxter wetting state.
- To investigate the influence of air-supersaturated water conditions and temperature changes on the plastron's dynamic behavior.
Main Methods:
- Utilizing textured superhydrophobic surfaces, specifically a centimeter-sized superhydrophobic sphere.
- Immersing the sphere in heated, air-supersaturated water and introducing a natural gas influx mechanism.
- Implementing rapid changes in water temperature to observe variations in the dynamic behavior of the air plastron.
- Quantifying air flux into the plastron and identifying the air transport model for plastron growth.
Main Results:
- A novel macroscopic, dynamic continuous air layer (plastron) was sustained indefinitely on textured superhydrophobic surfaces.
- The air plastron was shown to be an intermediate state between Leidenfrost vapor layers and the Cassie-Baxter wetting state.
- The plastron's dynamic behavior could be regulated by changes in water temperature and air saturation.
- Observed plastron growth dynamics and air bubble behavior were consistent with a well-mixed gas transport model.
Conclusions:
- The experimental demonstration confirms the indefinite sustainment of a dynamic air plastron on superhydrophobic surfaces in air-supersaturated water.
- This plastron represents a unique intermediate wetting state with potential applications in fluid manipulation and surface technologies.
- The study successfully quantified air flux and validated a gas transport model for plastron growth, offering insights into its stability and dynamics.
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