Interfacial Tension Hysteresis in Oxidizing Eutectic Gallium-Indium*

Eutectic gallium-indium (EGaIn), a room-temperature liquid metal alloy, has the largest interfacial tension of any liquid at room temperature. Under an applied voltage in an electrolytic bath, the interfacial tension of EGaIn is decreased by orders of magnitude. We observe that the interfacial tension depends not only on the applied voltage and the concentration of the bath’s electrolyte, but also exhibits history-dependence when the applied voltage is swept. We examine the interfacial tension’s dependence on voltage, voltage sweep rate and direction, and on time, and present a model of the droplet’s surface free energy as dependent on charge density and molecular composition of the interface to describe the voltage history dependence of the interfacial tension.