Micro−Micro Hierarchy Replacing Micro−Nano Hierarchy: A Precisely Controlled Way To Produce Wear-Resistant Superhydrophobic Polymer Surfaces

摘要

Superhydrophobic polymer surfaces are typically fabricated byncombining hierarchical micro-nanostructures. The surfaces have a greatntechnological potential because of their special water-repellent and selfcleaningnproperties. However, the poor mechanical robustness of such surfacesnhas severely limited their use in practical applications. This study presents ansimple and swift mass production method for manufacturing hierarchicallynstructured polymer surfaces at micrometer scale. Polypropylene surfacenstructuring was done using injection molding, where the microstructurednmolds were made with a microworking robot. The effect of the micro−nmicrostructuring on the polymer surface wettability and mechanical robustnessnwas studied and compared to the corresponding properties of micro−nnanostructured surfaces. The static contact angles of the micro−microstructurednsurfaces were greater than 150° and the contact angle hysteresis wasnlow, showing that the effect of hierarchy on the surface wetting properties works equally well at micrometer scale. Hierarchicallynmicro−microstructured polymer surfaces exhibited the same superhydrophobic wetting properties as did the hierarchicallynmicro−nanostructured surfaces. Micro−microstructures had superior mechanical robustness in wear tests as compared to thenmicro−nanostructured surfaces. The new microstructuring technique offers a precisely controlled way to producensuperhydrophobic wetting properties to injection moldable polymers with sufficiently high intrinsic hydrophobicity.