G. Oh, W.J. Jeong, B.M. Weon
Keywords: Marangoni flow, binary droplet, uniformity
Summary:Coffee stains left after droplet evaporation are important in inkjet printing technology because they would hinder uniform depositions. Here, we suggest a versatile way to suppress coffee stains with multiple solvents to control Marangoni flows during droplet evaporation. Control of Marangoni flows can be an important key to regulate stain uniformity. In particular, making two or three solvent mixed droplets is designed to manipulate flows with well-controlled concentration gradients along air-liquid interfaces. We observe and interpret the complex dynamics of evaporation from multi-solvent droplets. This result would be useful to improve stain regularity and uniform deposition of colloidal particles with ink jet printing or painting.