UV-resistant superhydrophobic surface on copper foil

Abstract

Superhydrophobic surfaces are widely used in various industrial and self-cleaning applications. Here, we present a low cost, facile synthesis of UV-resistant copper based superhydrophobic (SH) surface. The copper is electrochemically deposited on an another copper foil at the room temperature. The electrochemical bath consists of an aqueous solution of CuSO4 and H2SO4 acid. The samples were rinsed in ethanol and dried in a vacuum oven at 100 °C. The substrates were dip coated using 1 % Teflon AF solution to lower the surface energy. Also, another batch of copper surfaces was treated in stearic acid solution for hydrophobic coating. Both, the stearate and the Teflon coated copper surfaces shows hierarchical micro-nano surface morphology. The wetting properties on both the surfaces were extensively tested by static contact angle analysis, contact angle hysteresis (CAH) and droplet bouncing and rolling. Both the surfaces show, the average contact angle is about 165° and CAH is about 4°. The stability of the SH coating is tested against exposure to the ultraviolet (UV) A, B and C radiations. The Teflon AF coated surface retains SH property even after 2 hrs of UV exposure, whereas the stearate coating shows degradation in merely 30 min of exposure. Thus, the Teflon coated copper rough surface has potential in outdoor SH applications.