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Wetting of soap bubbles on topographic surfaces
Yasmin Howell1, Richard Blaikie2, Sam Lowrey2
1Department of Physics, University of Otago, 730 Cumberland Street, Dunedin 9016, New Zealand.
Journal of Colloid and Interface Science
|August 23, 2024
Summary
The static contact angle of soap bubbles on textured surfaces follows similar principles to droplets, as demonstrated by a new free energy model and experimental validation. This finding advances understanding of bubble behavior on complex topographies.
Area of Science:
- Surface science
- Fluid dynamics
- Materials science
Background:
- The static contact angle of droplets and soap bubbles on flat surfaces share a known relationship.
- This suggests a potential link between bubble behavior on topographic surfaces and droplet behavior on flat surfaces.
Purpose of the Study:
- To derive a relationship between the static contact angle of a soap bubble on a periodic topographic surface and a droplet on a flat homogeneous surface.
- To experimentally validate this derived relationship.
Main Methods:
- A free energy model was developed for the static contact angle of soap bubbles on topographic surfaces in the Cassie-Baxter state.
- Polydimethylsiloxane surfaces with varying area fractions and periodic topographies (lined, pillared) were fabricated.
- A bubble goniometer was used to measure the static contact angle of bubbles (40,000–50,000 mm³).
Main Results:
- The derived model predicts that the relationship for bubble contact angles on composite surfaces mirrors the Cassie-Baxter equation for droplets.
- Experimental measurements of static contact angles for both bubble volumes showed good agreement with the predicted trends.
Conclusions:
- The study successfully derived and validated a model linking soap bubble static contact angles on topographic surfaces to droplet behavior on flat surfaces.
- Findings support the applicability of Cassie-Baxter principles to bubble interactions with textured materials.
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