Superhydrophobic–superhydrophilic switchable wettability via TiO2 photoinduction electrochemical deposition on cellulose substrate

• We prepared a functional hybrid electrochemical sol.
• Hybrid electrochemical sol was deposited on cellulose substrate.
• The deposited cellulose substrate presents smart wetting converting performance.

An integrated approach to preparing a hybrid electrochemical sol using precursor tetrabutyl titanate and siliane coupling agents methyltriethoxysilane (MTES), γ-chloropropyltriethoxysilane (CPTS), N-octyltriethoxysilane (OTEOS) or dodecyltriethoxysilane (DTEOS) was investigated. The functional TiO2 and hydrophobic chain in hybrid electrochemical sol were deposited on cellulose substrate via sol–gel electrochemical deposition to present sensitive superhydrophobic–superhydrophilic smart converting performance. By doping 2% silane coupling agent in hybrid electrochemical sol and depositing at applied voltage 13 V for 8.0 min, the cellulose substrate showed excellent superhydrophobicity. The contact angle reached to 166.1° with OTEOS/TiO2 hybrid sol. During washing process, the contact angle of coated cellulose substrate declined to 161.3°, and decreased to about 119.1° after washing 10 times, which showed excellent washing durability for sol–gel electrochemical deposition. The contact angle was decreased to 0° during 105 μW/cm2 ultraviolet (UV) for 11.0 min, which was caused by the photoinduced TiO2 component, and the contact angle of the irradiated cellulose substrate recovered gradually in dark environment. When stored in the dark for 40 h, the contact angle could increase to 150.6°, and the fabric recovered to superhydrophobicity.

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