Contact angle hysteresis and lateral adhesion strength on random rough surfaces

Abstract

Based on the classical RJ 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.

Contact-angle hysteresis on rough surfaces: mechanical energy balance framework

“…More recent works have observed experimentally the pinning/depinning or 'stick-slip' behaviour of the fluid interface near the TPCL (Priest et al 2009;Forsberg et al 2010;Schellenberger et al 2016;Jiang et al 2019). Other studies have used a variety of energy conservation principles to extend the work of Joanny & de Gennes (1984) to periodic surfaces (Raj et al 2012;Butt et al 2017;Jiang et al 2019) or interpreted measurements of CAH in terms of contact-line energy dissipation and interfacial 'jumping' dynamics (Priest, Sedev & Ralston 2007Dorrer & Rühe 2008;Song et al 2022). Despite these successes, however, questions remain about this conceptual model of CAH; around what specific TPCL region should energy be conserved, how should the dissipation that occurs during the 'stick-slip' motion of the interface be calculated, and how can the energies of practical surfaces that may contain randomly shaped structures and/or micro-bubbles/droplets be included in such an analysis?…”

“…2019) or interpreted measurements of CAH in terms of contact-line energy dissipation and interfacial ‘jumping’ dynamics (Priest, Sedev & Ralston 2007, 2013; Dorrer & Rühe 2008; Song et al. 2022). Despite these successes, however, questions remain about this conceptual model of CAH; around what specific TPCL region should energy be conserved, how should the dissipation that occurs during the ‘stick–slip’ motion of the interface be calculated, and how can the energies of practical surfaces that may contain randomly shaped structures and/or micro-bubbles/droplets be included in such an analysis?…”

Contact angle hysteresis can modulate the Newtonian rod-climbing effect

“…It has been extensively studied in the past few decades and still an ongoing area of research. [17][18][19][20][21][22] Neglecting the CAH in the free surface problems near a solid surface is an oversimplification, and it may lead to wrong predictions. 6,23 In the case of the presence of CAH, the contact angle for a given system can exhibit a range of steady-state values.…”