Highly UV and Corrosion - Resistant Poly(vinylidene fluoride)‐Co‐Hexafluoropropylene - Carbon Nanotubes Superhydrophobic Nanocomposite Coating for C-Steel

Abstract

A robust superhydrophobic nanocomposite coating (PVDFHFP-CNTs) of poly(vinylidene fluoride)‐co‐hexafluoropropylene (PVDFHFP) and carbon nanotubes (CNTs) was fabricated on carbon steel using a two-step process: electrospinning and spray coating. The wettability properties of the prepared coating were inspected by measuring the water contact angle (WCA). Before the addition of CNTs, the WCA and the sliding angle (SA) of the PVDFHFP were 150°±3 and 2°±3, respectively while after the addition of CNTs, their values increased to 155°±2 and 3°±2, respectively. The wettability of the as-prepared coatings was also inspected after exposure to UV radiation with a light power of 0.89 W m-2 for 41 cycles according to ASTM standard D4587 – 11 (general metal coatings Standard) whereas each cycle includes 8 h exposure to UV illumination at 60 °C, and condensation for 4 h at 50 °C. It was found that the measured WCA and water contact water angle hysteresis (WCAH) for PVDFHFP-CNTs nanocomposite 152° ± 2 and 6° ± 2 compared to 147° ± 2 and 17° ± 3 of pure PVDFHFP, respectively. The morphology of the superhydrophobic coating was explored. It shows a beaded-like fiber structure. Spectra elements of the prepared coatings were obtained using the Fourier transform infrared instrument (FTIR). The surface roughness of the fabricated super water-repellent coatings were measured using atomic force microscope (AFM). The electrochemical behavior of superhydrophobic coating was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl before and after exposure to UV radiation. The outcomes showed the high corrosion resistance of PVDFHFP-CNTs compared to the neat PVDFHFP coating in presence and absence of UV.