Sewage Water-Repellent PDMS and Magnetic Silicone Composites: Lab to Commercialization

Liquid-repellentsurfaces are beneficial for improving corrosionresistance, anti-biofouling, anti-icing, and reducing material stickingin food, beverages, cosmetics, and medical industries. However, limitedresearch data are available on fabricating sewage water-repellentsurfaces, which should repel suspended organic/inorganic and biologicalmatter in addition to water. Herein, we unveil the sewage water repellencyand superhydrophobicity of magnetic silicone composites and poly(dimethylsiloxane)(PDMS). Hexagonally arranged microconical pillars (Wenzel roughnessof 1.2-2.4) were printed via hot embossingand replica molding methodologies. High static contact angles of & SIM;160 & DEG;,low contact angle hystereses of & SIM;5 & DEG;, and low roll-offangles of & SIM;5 & DEG; were achieved. At least 30 textured siliconecomposites were fabricated by successively hot embossing from a singlecustom-made and durable commercializable Ni-steel mold. Allof them demonstrated excellent replication efficiency and retainedsuperhydrophobicity and sewage water repellency as a function of embossingcycles. Furthermore, sewage water and deionized water droplets bouncedoff the silicone composite surface for a Weber number of up to 149,revealing a robust Cassie configuration. Furthermore, textured surfacesretained under-sewage water phobicity for up to 24 h, when submergedat 3 cm depth (0.3 kPa gauge pressure), wherein coated and untexturedsurfaces have failed just within 15 min, i.e., covered by a liquidfilm or sticky droplets. Also, textured surfaces inhibited the growthof the Escherichia coli bacterium,while a huge biofilm was observed on the untextured region. Briefly,this is the first demonstration of a one-step, upscalable, and facilehot embossing methodology to manufacture sewage water-repellent siliconecomposite and PDMS surfaces.