Self‐Texturing Scratch‐Resistant and Bacteria‐Repellent Superhydrophobic Polypropylene Surfaces Through Extrusion‐Based Additive Manufacturing

ABSTRACT Superhydrophobic surfaces with hierarchical nano‐ and micro‐structures are of immense importance for applications in highly frequented public spaces due to their self‐cleaning and germ‐repellent properties. Additive manufacturing enables creating such bioinspired multifunctional textures by digital design in just one 3D printing step. However, fused filament fabrication (FFF), also known as fused deposition modeling (FDM), is strictly limited to microstructure formation due to its comparatively low resolution. Herein, we overcome this limitation by exploiting in‐situ surface nanostructure formation via self‐assembly of innocuous behenic acid (BA) which was melt‐blended with glass fiber‐reinforced nanophase‐separated polypropylene (PP) reactor blends to produce superhydrophobic, scratch‐resistant and self‐healing PP surfaces. The digitized 3D printing process controls the formation of the PP microstructures and the BA nanocrystals on the PP surface, rendering the PP superhydrophobic. Moreover, the continuous migration and nanostructure formation of behenic acid enables self‐regeneration assuring durability of superhydrophobicity even after cleaning using surfactants. Microscopic surface imaging along with the measurement of contact angles (163°) and roll‐off angles (12°) confirm the superhydrophobic properties. Mechanical analyses and scratch tests demonstrate the outstanding robustness of these self‐texturing PP surfaces. According to adherence tests with salivary bacteria, the reduction in initial bacterial adhesion was found to be 87%.