Facile fabrication of superhydrophobic steel surfaces with self-cleaning ability using nickel myristate/PDMS bilayer coating

Abstract

Superhydrophobic (SHP) surface on 304 L SS was fabricated by a facile method using nickel myristate and polydimethylsiloxane (PDMS) bilayer coating. Surface preparation, electrodeposition and dip coating parameters were optimized to obtain uniform and adherent superhydrophobic coating with maximum water contact angle (WCA). Electrodeposited nickel myristate coating with siloxane overlayer on 304 L SS was characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and energy dispersive X-ray spectroscopy (EDS). FESEM images revealed hierarchical micro-nano structures of nickel myristate in the electrodeposited sample and a thin overlayer of PDMS. These samples showed a WCA of 170.7° ± 3.6° and a sliding angle (SA) of 4° ± 1°. The as-prepared sample retained its superhydophobic property in a wide pH range of 0 to 9, 1–5 M NaCl solution and 16 days immersion in mild alkali solution. Removal of contaminants on SHP surface with rolling water drops demonstrated its excellent self-cleaning ability. The chemical stability and self-cleaning ability of the electrodeposited sample coated with PDMS were found to be superior as compared to the only electrodeposited sample without PDMS coating. The chemical and mechanical durability of electrodeposited nickel myristate coating is improved by overlaying a PDMS layer, without compromising the hierarchical structures formed on the steel surface. This study provides an economical and straightforward method to fabricate chemically inert and self-cleaning superhydrophobic coating on 304 L SS substrate.