Effect of Evaporation Rate on Stick-Slip Behavior of the Contact Line

Droplet evaporation has a lot of industrial applications such as spray cooling, coating technology, and evaporative self-assembly. During evaporation of a drop on solid surface, maximum evaporation rate occurs at the contact line. Hence, the mechanism close to the contact line highly controls the process of the evaporation such as total evaporation time, pinning. Despite its importance, this mechanism is not yet fully understood. Theoretical and experimental studies focused on microscopic behavior of contact line have shown the dependence of contact angle on the rate of evaporation. Macroscopic theoretical studies have shown different behavior of the contact angle and droplet base radius for the case of strong and weak evaporation. A typical droplet evaporation consists of two well-defined stages. Constant radius mode occurs initially which is followed by a stick-slip mode. Stick-slip behavior of the contact line is a consequence of competition between unbalanced Young’s force and adhesion forces due to roughness. The present work is an experimental investigation of the effect of evaporation rate on macroscopic behavior of the contact line in case of stick-slip. This study contributes to the experimental knowledge of the physics of evaporation at macroscopic scale.