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

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-SiO2/CNF superhydrophobic coating (SHC) was successfully fabricated by designing “egg-shell” and “web-like” structures. We have in situ loaded nano-SiO2 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-SiO2/CNF SHC surface can lock the gas stably and block the diffusion of corrosive media into the coating. Therefore, the prepared PVDF/FAC-SiO2/CNF coating can withstand 250 kPa water flow impact and possesses high charge transfer resistance (1.44 × 1010 Ω cm2) 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% H2SO4. This fabrication process is scalable and provides a new avenue for the fabrication of robust superhydrophobic coatings.