Self-propulsion of surfactant droplets on inclined liquid films

Other presentation title : Mobilization and self-propulsion of surfactant droplets on thin liquid films. We present a systematic investigation of the self-propulsion of insoluble surfactant droplets on spatially confined thin liquid films, deposited on chemically patterned substrates. We studied the dependence of the propelled distance of the droplets on the initial height of the deposited film as well as the initial spreading pressure of the surfactant. We observed an emulsification process of subphase liquid inside the surfactant droplets which is coupled to their self-propelling motion. Using the thin-film approximation, a numerical model is developed for an insoluble surfactant drop moving at constant velocity at the liquid-air interface, the predictions of which compare favorably with the experimental data.