<< Theoretically, when a bubble reaches the surface of a pure liquid, the thin film of liquid between the bubble and the air above should quickly drain away, allowing the bubble to coalesce with the air. The same would be expected when two bubbles meet within the liquid or when two droplets of oil come together in water. >>
<< Counterintuitively, bubbles or droplets reaching the highly mobile fluorocarbon liquid-air interface bounced off of the interface much more strongly than from the immobilized interface. The reason is that there is less friction on the mobile interface and thus less energy is lost during the bounce. "To our knowledge, our studies and simulations are the first to demonstrate an enhanced bounce effect due to interface mobility," >> Ivan U. Vakarelski.
When bubbles bounce back. King Abdullah University of Science and Technology. Nov 13, 2019.
https://m.phys.org/news/2019-11-when-bubbles-bounce-back.html
Ivan U. Vakarelski, Fan Yang, et al.
Mobile-surface bubbles and droplets coalesce faster but bounce stronger. Science Advances 25 Oct 2019:
Vol. 5, no. 10, eaaw4292 DOI: 10.1126/sciadv.aaw4292
https://advances.sciencemag.org/content/5/10/eaaw4292
