Contact angle hysteresis and lateral adhesion strength on random rough surfaces

Abstract

Based on the classical Robbins–Joanny model of contact angle hysteresis, a new dimensionless parameter ( q0/ q2) sensitive to roughness power spectrum is proposed to be linearly related to (1) contact angle hysteresis caused by roughness heterogeneity and (2) lateral adhesion strength of a sliding water bridge. Both hypotheses were validated using liquid bridge sliding experiments on random rough surfaces. q0/ q2 qualitatively reflects the decay rate of any two points on the surface from mutually independent to correlated with diminishing separation distance.