Periodic collective behaviors of organic solvent droplets on the surface of aqueous surfactant solutions

Abstract

Active matter sometimes exhibits lifelike complex spatiotemporal patterns. Here we report on complex oscillatory behaviors of droplets floating on an aqueous surfactant solution. Even if the droplets consist of only simple chemicals, the behaviors they exhibit are unexpectedly complicated. They are likely induced by the interaction among droplets, which is mediated through the surface tension field as well as Marangoni flow field created by the droplets themselves.

Interface-Driven Spontaneous Differentiation-Repulsion Behavior in Isochemical Droplet Populations

“…1a). We opted for 1-decanol (C10H21OH; referred simply as decanol from here onwards), a straightchain primary alcohol, as our oil-of-choice, owing to its very low solubility in water (37 mg/mL at 25 °C), its density being lower than water (830 kg/m 3 ) allowing the droplets to float, and its wide usage in biomimetic systems 19,20,26,27 . We used pure water without any additives (salts or surfactants), except for specific experiments.…”