Impact of chaotic or organized chemical texturing on wetting dynamics using numerical simulations

In wetting theory, it has been defined that contact angle hysteresis and, more generally, dynamic behavior originate from the imperfect nature of the surface, such as chemical and topographical asperities. In the case of chemical heterogeneities, the clustering effect of polar and non-polar groups is assumed to be at the origin of droplet anchoring behavior. Then, on a microscopic scale, the organization of these groups should have an impact on wetting dynamics. As a hypothesis, for an identical surface ratio of two distinct chemistries with the same asperity size, a surface with a chaotic chemical distribution will generate more anchoring than an organized surface. To verify this approach, a numerical model was applied to wetting on textured chemical surfaces. Numerical wetting simulations were developed to simulate wetting in a manner similar to a sessile drop experiment followed by a tilt test. In addition, thanks to the numerical method, it was possible to precisely define different chemical textures, ranging from a totally chaotic texture to an organized one. Dynamic anchoring behaviors were then characterized, for each surface, by the evolution of the triple line velocity during droplet sliding. As a result, the simulations validate the initial hypothesis with the observation of stronger dynamic anchoring during tilting for randomly textured surfaces. This behavior is directly linked to the clustering effect, which creates favorable anchoring sites. It has been shown that this clustering effect also leads to local stick–slip phenomena of the triple line around the droplet. • Wetting dynamic behaviors can be characterized by LBM simulations on tilted surface. • Organized distribution exhibit less dynamic anchoring than chaotic distribution. • Above a certain alteration size, pinning of the triple phase line occurs, reducing droplet motion for both distributions. • Clustering effect in randomly distributed alterations generates more pinning and stick–slip phenomena.