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Movies

Movies of interfacial phenomena and pattern formation

Self-motion of oil droplet on a glass surface

In an aqueous phase containing surfactant that is able to adhere on a glass surface, an oil droplet which contains chemicals that makes pairs with the surfactant moves spontaneously on a glass surface.
We have found that the motion of an oil droplet becomes regular when that is placed in an appropriate boundary condition whereas in an isotropic condition an oil droplet moves irregularly.


Tears of wine

The thin film of water-ethanol mixture spontaneously climbs up glass surface when the ethanolevaporates from the film. Since the evaporation of ethanol is slower near the bulk of the mixture, there occurs the gradient of ethanol concentration on the film. Ethanol is surface active chemical; therefore, surface tension of the mixture is higher at the top of film. This unbalanced surface tension results in the Marangoni flow. Finally, the liquid is spontaneously soaked up to the higher glass surface, and by the effect of gravity, the mixture forms droplet on the glass surface.


Artificial amoeba

Placing an oil droplet with fatty acid on an aqueous phase with cationic surfactant, the oil droplet spontaneously deforms its interface in the absence of any biological components. Accompanied with the spontaneous deformation, surfactant aggregation is formed in the aqueous phase close to the oil-water interface. This aggregate is elastic and compress the oil droplet. As a result, the droplet behaves as if it is artificial amoeba.


Belousov-Zhabotinsky reaction

Famous chemical reaction that shows temporal pattern i.e. oscillation, as well as spatial pattern i.e. target and spiral pattern. 
 

Other various movies

You can see the simplest type of self-propelled object driven by Marangoni flow (detergent boat). You can also see the Benard convection.