Superhydrophobic TiO2/polyvinylidene fluoride composite surface with reversible wettability switching and corrosion resistance

• Superhydrophobicity is achieved on the Cu substrates.
• The surface exhibits a water contact angle of 162.3° and a sliding angle of 4.3°.
• The coating surface can convert superhydrophobicity to and from hydrophilicity.
• The superhydrophobic surface possesses good durability and corrosion resistance.

Herein, we present a simple and practical approach to for the facile preparation of superhydrophobic modified-TiO2/polyvinylidene fluoride composite surface on the Cu substrate via a dip-coating process. Fourier transform infrared spectrometry, scanning electron microscope, atomic force microscope and X-ray photoelectron spectroscopy were employed to characterize the chemical compositions and surface morphologies. The results show that the hydrophobic –CF2– and –CF3 groups were introduced into TiO2 particles by modification, the as-prepared superhydrophobic composite surface with a water contact angle of 160.1° and a sliding angle of 5.5° is due to the assembly of low-surface-energy materials on it and its rough surface with micro/nano structures. Interestingly, the superhydrophobic composite surface can realize reversible switching between superhydrophobicity and superhydrophilicity through the alternate treatment by UV light irradiation and heating. Additionally, polarization curves and electrochemical impedance spectroscopy measurements demonstrated that the superhydrophobic composite surface greatly improved the corrosion resistance of Cu substrate in 3.5 wt.% NaCl solution. Furthermore, the superhydrophobic composite surface not only can be constructed on various substrates, but also shows good long-term stability in air. We believe that this approach would potentially be used in various important applications, such as controlling the wettability of surfaces and corrosion resistance of metal substrates.

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