Chemo-Mechanical Coupling in Reactive Droplets

Chemo-mechanical coupling is studied in droplets containing an oscillating Belousov-Zhabotinsky (BZ) reaction medium surrounded by a solution of lipids in n-decane. We identified experimental conditions at which the oxidation state of the catalyst significantly changes the interfacial tensions of the BZ droplet. During oxidation episodes, a fraction of the catalyst incorporates into the membrane, whereas during the slower reduction phase it returns to the aqueous phase. The catalyst is partly replaced by lipids that were originally dissolved in the organic phase, thus increasing the surface of the droplet. As a result of this increase in surface area, a droplet placed in a trench on the bottom of the reactor periodically elongates in phase with the chemical oscillations.