Marangoni effect

Soap films have theremarkable property of self-healing. A water drop, like the one shown below, can pass through a bubble (repeatedly!) without popping it. This happens thanks to surfactants and the Marangoni effect.

Surfactants are molecules that lower the surface tension of a liquid and congregate along the outermost layer of a soap film. When water breaks through the soap film, its lack of surfactants causes a higher surface tension locally. This triggers the Marangoni effect, in which flow moves from areas of low surface tension toward ones of high surface tension.

That carries surfactants to the region where the drop broke through and helps stabilize and heal the soap film. Incidentally, the same process lets you stick your finger into a bubble without popping it as long as your hand is wet!

What is Marangoni Effect? Read & Learn: https://www.nasa.gov/mission_pages/station/research/news/marangoni.html

What are surfactants? Read & Learn:
http://www.essentialchemicalindustry.org/materials-and-applications/surfactants.html

Image credit: G. Mitchell and P. Taylor
https://www.youtube.com/watch?v=0h16Tyn2138

Story via FYFD
https://twitter.com/fyfluiddynamics

Animated Photo

 

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