Durable superhydrophobic surface prepared by designing “micro-eggshell” and “web-like” structures

Abstract

A durable superhydrophobic PVDF/FAC-SiO 2 /CNF coating with stable superhydrophobicity was prepared by designing “egg-shell” and “web-like” structures. Combined with the eggshell and web-like structure, the stable air cushion trapped on the PVDF/FAC-SiO 2 /CNF SHC surface can provide excellent hydrophobic stability, even for slurry, hot water or 98% H 2 SO 4 . • A novel superhydrophobic coating was successfully prepared by designing ‘micro-eggshell’ and ‘web-like’ structures. • The locked gas of “egg-shell” and “web-like” can enhance the hydrophobic stability of the coating surface. • The PVDF/FAC-SiO 2 /CNF coating can withstand hot water immersion or 98% H 2 SO 4 dumped. • The prepared coating possesses high charge transfer resistance (1.44 × 10 10 Ω cm 2 ) after 30 d immersion. Superhydrophobic surfaces (SHSs) have drawn a lot of interest in both academic and industry by its special wettability, but most artificial SHSs suffer from their poor hydrophobic and mechanical durability. Here, a durable PVDF/FAC-SiO 2 /CNF superhydrophobic coating (SHC) was successfully fabricated by designing “egg-shell” and “web-like” structures. We have in situ loaded nano-SiO 2 particles on the azodicarbonamide (AC) surface to provide a layer of barrier, which can prompt the formation of a special egg-shell structure after AC thermal decomposition. Moreover, CNF divided the pore structure to smaller spaces by forming web-like structure in the coating surface. Cooperation of the egg-shell and web-like structures, the PVDF/FAC-SiO 2 /CNF SHC surface can lock the gas stably and block the diffusion of corrosive media into the coating. Therefore, the prepared PVDF/FAC-SiO 2 /CNF coating can withstand 250 kPa water flow impact and possesses high charge transfer resistance (1.44 × 10 10 Ω cm 2 ) after 30 d immersion in 3.5 wt% NaCl solution. Furthermore, the prepared coating also exhibited outstanding mechanical and hydrophobic stability, which can maintain its superhydrophobicity even after 1000 abrasion cycles, hot water immersion, or dealing with 98% H 2 SO 4 . This fabrication process is scalable and provides a new avenue for the fabrication of robust superhydrophobic coatings.