Rougher is more slippery: How adhesive friction decreases with increasing surface roughness due to the suppression of capillary adhesion

Friction originates at the area of real contact which depends on (changing) surface topography. Observing and measuring multi-asperity interfaces is difficult, making it challenging to quantitatively study interplay between frictional force In this paper, we systematically manipulate topography use a fluorescence microscopy-based visualization technique reveal interplay. We demonstrate good agreement elastoplastic boundary element method calculations experimental contact. While thus pressure could be varied by factor 4 through control topography, had only modest effect coefficient friction (CoF). do find small but systematic increase in proportionality constant normal (CoF) with decreasing roughness. The observation that smoother surfaces have greater CoF due capillary adhesion two surfaces. model behavior using simple without adjustable parameters. Our results provide quantitative insights into mechanics, friction, adhesion. A predictive understanding essential demanding applications such as precision positioning.