Biological & Soft Matter Seminar: Self-lubricated spreading of surfactant-laden droplets

Abstarct:

While surfactants are known to affect fluid-fluid interfaces, their impact on solid-liquid interfaces is an open problem. We show that surfactants carried by spreading droplets can modify the solid-liquid interfacial energy and induce concentration-dependent spreading, faster than Tanner’s law. The transition between the spreading trends arises from a non-uniform surfactant adsorption that reduces the droplet basal stress. Our theory is consistent with our laboratory experiments, providing control means for droplet motion, with relevance to microfluidic systems, coating, and surface treatment.