RESUMO
We propose a kinetic description of ionic surfactant transfer across an interface between two immiscible electrolyte solutions that includes interfacial processes (charging of the interface, adsorption, and direct ion transfer) as well as characteristics of the electrical circuit. Our model demonstrates that experimentally observed irregular current oscillations may stem from a dynamical instability of the system which is induced by the interplay between a potential-dependent adsorption and direct ionic transfer across the interface. Calculated temporal patterns exhibit dynamical features which agree well with the experimental observations; in particular, we found that current anomalies occur in a vicinity of the standard ion transfer potential, and the presence of the irregular current oscillations depends on the rate and direction of potential scans.
RESUMO
A theory of electrowetting is developed for systems containing an interface between two immiscible electrolytic solutions. Laws for the dependence of contact angle on electrode potential are presented. Ionic impermeability of the liquid-liquid interface and nonlinear double-layer responses rationalize observed phenomena such as contact-angle saturation and droplet contraction or detachment. The theoretical results can be applied to design new, precisely controllable microfluidic devices.
