Contact angle hysteresis of Newtonian fluid

Abstract

Contact angle hysteresis of Newtonian fluid is a fundamental and complicated phenomenon related to wetting and dewetting. This article reviews typical research progress of contact angle hysteresis and proposes some critical directions deserved to be investigated. The traditional measuring methods are not accurate to measure the contact angle, and the conventional definition is not suitable for the Wenzel, Cassie, or the intersection of the two states. The surface roughness and droplet size are important factors affecting the hysteresis. Effective roughness scale for hysteresis could be at nanoscale. The difference between microscopic and macroscopic contact angle leads to different hysteresis at microscopic scale, which is valuable for nanodevice.