Supersolvophobic Soft Wetting: Nanoscale Elastocapillarity, Adhesion, and Retention of a Drop Behaving as a Nanoparticle

Abstract

Summary Understanding the drop behavior on either hydrophobic (solvophobic) surfaces or soft surfaces is essential for applications in heat exchangers, self-cleaning surfaces, and condensation-promoting and coffee-stain-arresting surfaces. Here, we probe—through molecular dynamics simulations—the drop dynamics on a surface that is both phobic and soft, represented as a surface grafted with a layer of solvophobic polymer brushes. We discover that the drop behaves like a nanoparticle and deforms the polymer brush layer by elastocapillary adhesion, ensuring that the resulting contact angles obey Young's law. Furthermore, the brush layer with a smaller stiffness (representing a surface of reduced elasticity) (1) experiences an elastocapillarity-adhesion-mediated enhanced soft-solid deformation that closely follows the prediction of the JKR law, (2) leads to a weakened drop motion (as a translation of a nanoparticle) and a weakened motion of the deformed solid ridge, and (3) enforces a large retentivity of the drops on the brush layer.