Theoretical analysis for dynamic contact angle hysteresis on chemically patterned surfaces

TL;DR

This paper presents a theoretical model for dynamic contact angle hysteresis on chemically patterned surfaces, capturing essential contact angle dynamics and explaining experimental observations of asymmetry in advancing and receding angles.

Contribution

A simplified theoretical model based on the Onsager principle for contact angle hysteresis on chemically inhomogeneous surfaces is introduced, providing bounds and insights into contact angle dynamics.

Findings

Derived bounds for advancing and receding contact angles.

Model predictions align with numerical simulations.

Explains asymmetry in contact angles observed experimentally.

Abstract

A dynamic wetting problem is studied for a moving thin fiber inserted in fluid and with a chemically inhomogeneous surface. A reduced model is derived for contact angle hysteresis by using the Onsager principle as an approximation tool. The model is simple and captures the essential dynamics of the contact angle. From this model we derive an upper bound of the advancing contact angle and a lower bound of the receding angle, which are verified by numerical simulations. The results are consistent with the quasi-static results. The model can also be used to understand the asymmetric dependence of the advancing and receding contact angles on the fiber velocity, which is observed recently in physical experiments reported in Guan et al Phys. Rev. Lett. 2016.