EQUILIBRIUM CONTACT-ANGLE AND INTRINSIC WETTING HYSTERESIS

Wetting and adhesion should be treated as inherently irreversible proc esses, because, in the process of joining and separating two surfaces, available energy is dissipated. In a system that undergoes inherently irreversible processes, the second law of thermodynamics is always sa tisfied and can offer no information regarding the system's equilibriu m state. Therefore, to determine the equilibrium wetting angle, the la w of energy conservation should be used. As a result, the advancing co ntact angle is found to be intrinsically higher than the receding one, regardless of the surface heterogeneity, and the extent of hysteresis is dependent on the amount of energy dissipated in the process of wet ting and dewetting. (C) 1995 American Institute of Physics.