Multi-Scale In-Situ Tribological Studies of Surfaces with 3D Textures Fabricated via Two-Photon Lithography and Replica Molding

Surface texturing not only decreases friction by reducing the real area of contact but also is crucial for achieving multifunctionality. However, texturing a surface might undermine its deformation resistance due to increased sliding contact pressure. High resolution, 3D control over texture shapes can potentially address this issue. Utilizing a micro/nano‐scale additive manufacturing method based on two‐photon polymerization, textures are fabricated with precise shape, dimension, and position control. This allows for a systematic investigation of the effects of texture three‐dimensionality by comparing 3D textures (truncated cones) with 2.5D textures (cylinders and rods). Moreover, macro‐ and micro‐scale tribological testing and in situ monitoring of the experiments using a digital microscope at macro‐scale and a scanning electron microscope (SEM) at micro‐scale provides unique insights into the multi‐scale tribological properties of the textured surfaces by real‐time monitoring of the interplay between the forces and the sliding surfaces down to a single micro‐scale structure level. Macro‐scale tests show that cones not only have a lower coefficient of friction due to their reduced area of contact but also slide more smoothly and are more durable. Micro‐scale tests shed new light on the relationship between friction and the microstructure deformation by in situ SEM monitoring of texture‐counterface interactions