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Fluorine-Free Superhydrophobic Coatings with pH-induced Wettability Transition for Controllable Oil–Water Separation

2016; American Chemical Society; Volume: 8; Issue: 8 Linguagem: Inglês

10.1021/acsami.5b11720

1944-8252

Zhiguang Xu, Yan Zhao, Hongxia Wang, Hua Zhou, Chuanxiang Qin, Xungai Wang, Tong Lin,

High voltage insulation and dielectric phenomena

We present a simple, environmentally friendly approach to fabricating superhydrophobic coatings with pH-induced wettability transition. The coatings are prepared from a mixture of silica nanoparticles and decanoic acid-modified TiO2. When the coating is applied on cotton fabric, the fabric turns superhydrophobic in air but superoleophilic in neutral aqueous environment. It is permeable to oil fluids but impermeable to water. However, when the coated fabric is placed in basic aqueous solution or ammonia vapor, it turns hydrophilic but underwater superoleophobic, thus allowing water to penetrate through but blocking oil. Therefore, such a unique, selective water/oil permeation feature makes the treated fabric have capability to separate either oil or water from a water–oil mixture. It may be useful for development of smart oil–water separators, microfluidic valves, and lab-on-a-chip devices.