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On the rebound of soapy drops
Aditya Jha1, Auriane Huyghues Despointes1, Christophe Clanet2
1Physique et Mécanique des Milieux Hétérogènes, UMR 7636 du CNRS, PSL Research University, ESPCI, 75005, Paris, France.
Soft Matter
|November 13, 2023
Summary
Water drops can bounce off super-hydrophobic surfaces even with reduced surface tension. Lowering surface tension slows bouncing, but dynamic effects allow some liquids to rebound unexpectedly.
Area of Science:
- Surface Science
- Fluid Dynamics
- Materials Science
Background:
- Super-hydrophobic materials exhibit water repellency.
- Water's surface tension influences its interaction with surfaces.
Purpose of the Study:
- Investigate water drop bouncing on super-hydrophobic surfaces with lowered surface tension.
- Determine the threshold surface tension for drop rebound.
- Analyze the effects of alcohol and surfactants on water's surface tension and bouncing behavior.
Main Methods:
- Experimental determination of surface tension thresholds.
- Observation of drop impact and rebound dynamics.
- Analysis of dynamic surface tension effects.
Main Results:
- A surface tension threshold below which drops adhere to the substrate was identified.
- Decreased surface tension leads to slower rebound due to reduced liquid stiffness.
- Liquids with 'slow' surfactants can rebound below the static threshold due to dynamic surface tension effects.
Conclusions:
- Water drop bouncing on super-hydrophobic surfaces is possible even with reduced surface tension.
- Dynamic surface tension plays a crucial role in rebound phenomena, especially with surfactants.
- Liquid deformation during impact can alter surface properties, enabling repellency in otherwise wetting liquids.
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