Early time spreading of nanobubble-dispersed aqueous drops on oil-solid interfaces

Nanobubbles suspensions play an important role in numerous applications, including fabrication of functional materials, drug delivery, water treatment, carbon dioxide capture, and surface decontamination. The dynamic wetting of drops containing nanobubbles on solid surfaces is key to design the mass transport, adsorption, and reaction processes. Generally, the presence of surface-active materials in a drop may generate Marangoni stresses which can reduces the rapid motion of three phase contact line at the early time of the spreading process. Herein, we experimentally characterize the early time spreading dynamics of nanobubble-laden surfactant drops on a hydrophilic glass, submerged in an oil phase. We report that nanobubbles, when dispersed in the surfactant solution, can reduce the duration of the early time retardation regime, for instance from 0.2 to 0.02 s. The retardation time is found to be a decreasing function of nanobubble concentration.