Marangoni flows triggered by interactions of cationic-anionic surfactant mixtures

Marangoni flow, which is an interfacial flow triggered by surface tension gradients, is a topic of broad interest in complex fluids and interface communities. In this study, we investigate the interplay between cationic and anionic surfactant interactions in Marangoni flow patterns. By introducing a minute droplet of cationic surfactant into a bath of anionic surfactant, and vice versa, we observe diverse flow patterns resulting from the reactive transport of cationic-anionic surfactant mixtures due to surfactant-surfactant complexation. Our approach combines reaction kinetics, interfacial tension measurements, high-speed flow visualization, thermal imaging, and computational simulations to unravel the underlying mechanisms governing the observed flow phenomena. These insights shed light on the potential applications of our research, such as developing effective oil remediation techniques or understanding the spreading of waterborne pathogens in contaminated water bodies.