Superhydrophobic Nanocrystalline Nickel Films Inspired by Lotus Leaf
ABSTRACTA new method to fabricate superhydrophobic hard films is described. Surface texture of lotus leaf was replicated on an acetate film, on which a nanocrystalline (NC) Ni coating with a grain size of 30 ± 4 nm and a hardness of 4.42 GPa was electrodeposited. The surface texture consisted of conical protuberances with a height of 10.0 ± 2.0 0m and a tip radius of 2.5 ± 0.5 0m. An additional electrodeposition for 120 s and 300 s was used to locally modify the surface structure by depositing ‘Ni crowns' on the protuberances that increased their height to 14.0 ± 2.0 0m and their tip radius to 6.0 ± 0.5 0m. The modified structures were then treated with a perfluoropolyether (PFPE) solution, which provided a high water contact angle of 156°, i.e., comparable to the naturally superhydrophobic lotus leaf. The increased hydrophobicity as a result of surface structure and chemistry modifications was evident compared to a smooth NC Ni sample, which had a contact angle of 64°.