The tunability and influence of wetting on liquid/solid interfaces

Wetting, the study of how a liquid spreads on a solid (or a immiscible liquid) substrate, is crucial for a number of biological and engineering applications, such as wetting of the eye, rise of sap in a plant, and the anti-frost of airplane surfaces. Wetting not only influences the adhesion of nanometer-sized objects but also affects the transport of ions. It is believed that the wetting contact angle between water droplets and solids is increased by adding inorganic salts to water. Previous work suggests that the cosine of the contact angle is proportional to the inverse of liquid/vapor surface tension (Bonn, Daniel; Eggers, Jens; Indekeu, Joseph; Meunier, Jacques; Rolley, Etienne 2009). However, this inverse relation breaks down when the solid/liquid interfacial tension is strongly dependent on the presence of salt. Here, we use molecular dynamics simulations to investigate and understand the effect of liquid composition on the water contact angle on solid surfaces. Our work sheds light on the microscopic mechanisms of wetting and ion transport at solid/liquid interfaces.