Transition from the Wenzel to Cassie-Baxter state by PFOTES/TiO₂ nanoparticles leading to a mechanically robust and damage/contamination-recoverable surface

Here, we introduce a highly robust and damage/contamination-recoverable superhydrophobic surface consisting of 1H,1H,2H,2H-perfluorooctyltriethoxysilane bonded titanium dioxide nanoparticles (PFOTES/TiO2 NPs) and ultra-high-molecular-weight polyethylene (UHMWPE). The addition of PFOTES/TiO2 NPs into UHMWPE transformed the surface wettability from the Wenzel to the Cassie-Baxter state. The superhydrophobicity of the surfaces remained after 80 or 100 cycles of sand dropping, sandpaper abrasion and adhesive tape peeling, and even after making 2000 scalpel scratches. They were stable under heat at 180 degrees C and repellent to water droplets with various water pH levels. The mechanical compression, impact, and bending tests showed that the mechanical strengths of the superhydrophobic surfaces were more prominent than those of high-strength cement, a highly robust material. Even when the surfaces were damaged and contaminated by a gas flame, aqua regia, paint, oil and blood, their superhydrophobicity was readily recovered through a simple abrasion process by rubbing with sandpaper. This strategy for the production of a robust superhydrophobic surface recoverable from damage and contamination could help move the superhydrophobic surface to real-world applications.