Mechanically Stable Superhydrophobic Surface Fabricated by Self-Growth of ZnO Nanoflowers on Vulcanized Silicone Rubber

The development of superhydrophobic materials in practical applications have been severely hindered by the complexity of manufacturing and the sensitivity to mechanical contact. In order to prepare a mechanically durable flexible super-hydrophobic surface on the surface of a flexible substrate (vulcanized silicone rubber). In the paper, using the reversible characteristics of the swelling process of vulcanized silicone rubber and improved the sol-gel method, the silicone rubber sheet was swelled with a n-butylamine aqueous solution in advance, and then immersed in zinc nitrate/ethanol solution. Due to the cross-diffusion, contact and reaction between zinc nitrate and n-butylamine aqueous solution on the surface of silicone rubber, ZnO nanoflowers were grown in-situ on the rubber surface. The construction of the superhydrophobic rough structure came from the synergistic effect of zinc nitrate and n-butylamine, with static contact angle and rolling angle being (158±1.5)°and (4.5±0.5)° respectively. SEM images showed that ZnO nanosheets of 100-200 nm in thickness were generated and the ZnO nanosheets were “embedded”, not just “deposited” on the rubber surface, which improved the mechanical durability. By adding a silane coupling agent γ-aminopropyltriethoxysilane(KH550) to the silicone rubber compounds, the interface interaction between the ZnO nanosheets and the rubber matrix was further improved. Even with 300 times of linear wear, it could still maintain superhydrophobic and exhibit excellent mechanical stability. Moreover, after 500 cycles of bending deformation, its hydrophobicity hardly changes, which solved the problem of superhydrophobic coating falling off when the substrate was bent and deformed. High mechanical stability and simple preparation process endowed the superhydrophobic rubber a high application prospect.