Mechanism of the Cassie-Wenzel transition via the atomistic and continuum string methods

TL;DR

This paper investigates the atomistic and continuum mechanisms of the Cassie-Wenzel transition in superhydrophobic surfaces using the string method, revealing how cavity geometry influences wetting and proposing a faster computational approach.

Contribution

It introduces an atomistic string method for the Cassie-Wenzel transition and compares it with CREaM, enhancing understanding and computational efficiency in wetting mechanism analysis.

Findings

Wetting mechanism depends on cavity geometry.

Atomistic string method effectively captures transition pathways.

CREaM provides a faster, simpler computation method.

Abstract

The string method is a general and flexible strategy to compute the most probable transition path for an activated process (rare event). We apply here the atomistic string method in the density field to the Cassie-Wenzel transition, a central problem in the field of superhydrophobicity. We discuss in detail the mechanism of wetting of a submerged hydrophobic cavity of nanometer size and its dependence on the geometry of the cavity. Furthermore, we discuss the algorithmic analogies between the string method and CREaM [Giacomello et al., Phys. Rev. Lett. 109, 226102 (2012)], a method inspired by the string that allows for a faster and simpler computation of the mechanism and of the free-energy profiles of the wetting process. This approach is general and can be employed in mesoscale and macroscopic calculations.