Water jet resistant superhydrophobic carbonaceous films by flame synthesis and tribocharging

Flame synthesized nanostructured carbonaceous films are known to demonstrate water repellency due to inherent hydrophobicity of soot particles as well as the formation of dual scale roughness during deposition. However, their main drawback is that the films do not form a firm bonding with the surface upon which they are assembled, considerably reducing their real-time applications in liquid repellent surface technologies. Here, we demonstrate a simple, rapid, solvent-free and cost-effective strategy to synthesize water jet impact resistant carbonaceous films on randomly micro-textured surfaces. We utilize the concepts of polymer tribocharging and adhesion and diffusion flame synthesis on surfaces including flexible substrates. We also show that once saturated (became superhydrophilic) under certain water jet impact conditions, the surfaces still maintain sufficient texture and roughness which can be functionalized by a simple aqueous fluoropolymer treatment rendering them superhydrophobic also resistant to wetting by various oils. These nanostructured carbon surfaces show remarkable resistance to saturation by high-pressure impinging water jets under normal or oblique conditions. The results were interpreted within the framework of hydraulic jump theories. A number of potential applications can be envisioned such as condensation management and boiling as well as corrosion prevention under water jet impact conditions.