Abstract
Stimuli-responsive materials with controlled reversible wettability find diverse application as self-cleaning surfaces, tunable optical lenses and microfluidic devices. We report on an electrochemical approach for dynamic control over the wetting properties of additive-free Cu/CuxO core-shell dendritic structures. By varying the oxidation state of the oxide shell phase, the entire wettability range spanning superhydrophobicity (contact angle > 150°) to superhydrophilicity (contact angle < 10°) can be precisely adjusted in-situ. During the wetting transitions, the surface transforms from a low adhesive rolling state (lotus effect) to high adhesive pinning state (petal effect), and eventually to superhydrophilic state with a water-absorbing ability (fish scale wetting). The wetting alteration is reversible via air-drying at room temperature or mild heat drying at 100°C. The reversibly redox-driven wettability switching is demonstrated for controllable oil-water separation with efficiency higher than 98 percent.
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Kung, C.H., Zahiri, B., Sow, P.K. et al. Electrochemical Wettability Control on Cu/CuxO Core-Shell Dendrites: In-Situ Droplet Modulation and On-Demand Oil-Water Separation. MRS Advances 3, 3163–3169 (2018). https://doi.org/10.1557/adv.2018.335
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DOI: https://doi.org/10.1557/adv.2018.335