Durable superhydrophobic coatings based on flower-like zinc oxide via layer by layer spraying

Superhydrophobic coatings have attracted much attention due to their wide applications. However, they have poor durability when exposed to severe environmental conditions or external forces, which limited their application in outdoor environments. To deal with this problem, we prepared a durable superhydrophobic composite coating based on epoxy resin/flower-like zinc oxide/polydimethylsiloxane (ER/F-ZnO/PDMS) by a facile approach via layer by layer spraying. The F-ZnO was used to construct rough micro-nanometer scale structures and endow the coating with UV-protective ability. ER was applied to render mechanical strength and coating-substrate adhesion. PDMS was applied to further improve the hydrophobic performance of the coating. The effects of the mass ratio of F-ZnO and ER(MF-ZnO: MER), PDMS, and F-ZnO (MPDMS: MF-ZnO) on the hydrophobicity and durability of the composite coatings were investigated. When the MF-ZnO:MER and MPDMS:MF-ZnO were 13:5 and 0.075:1, respectively, the superhydrophobic coating exhibited excellent water-repellency with a water contact angle of 161.3 ± 2.3°, and sliding angle of only 0.8 ± 0.1°. Moreover, it possessed strong durability under severe environments, such as 120 sandpaper abrasion cycles, 5 high and low-temperature alternatively cycling, and intense ultraviolet irradiation for 40 h. The superhydrophobic coating showed outstanding antifouling properties for common liquid stains and muddy water.