Directional Droplet Wetting on Cellulose Surfaces with Physical Modification.

Directional wetting of liquids on solid surfaces is crucial for numerous applications. However, the impact of physical modifications on near-superhydrophilic cellulose has received limited attention as it is widely considered unfeasible. In this study, we present a previously unreported and simple but effective mechanism of directional wetting induced purely by physical modifications on pristine cellulose surfaces. By using molecular dynamics simulations, we unveil that a wedge-like surface roughness drives anisotropic water spreading, contrasting with the conventional understanding of uniform wetting on strong hydrophilic cellulose surfaces. This wedge-induced directional wetting occurs without any chemical alterations, showcasing the ability of the physical topography alone to control liquid dynamics. Our findings not only provide new fundamental insights into manipulating wetting behavior on naturally hydrophilic surfaces but also highlight a transformative approach to designing cellulose-based materials with tailored fluid flow properties for diverse applications.