Membranes with selective wettability for oil-water separation
In our recent work, we successfully fabricated hygro-responsive (from the Greek word ‘hygra’ meaning liquid) membranes that are both superhydrophilic and superoleophobic in air and underwater. Our membrane can separate surfactant-stabilized oil-in-water and water-in-oil emulsions (emulsion diameter: 10–20 μm) solely under gravity. We also demonstrated that the membrane could separate virtually all types of oil–water mixtures, solely under gravity, with η > 99% separation efficiency. For more information see “Hygro-responsive membranes for effective oil-water separation”, Nature Communications, 2012, 3, 1025. DOI: 10.1038/2027.
Super-repellent (superomniphobic) surfaces
A surface is considered to be super-repellent (superomniphobic) when it displays very high contact angles (typically >150) and very low contact angle hysteresis (difference between advancing and receding contact angles, typically < 5) for a contacting liquid. We developed the first-ever superomniphobic surfaces by considering the effects of hierarchical surface texture on surface wettability. For more information, see “The design and applications of superomniphobic surfaces”, NPG Asia Materials, 2014, 6, e109.
Photo-responsive surfaces for manipulation of liquid motion
We recently demonstrated that a dye-sensitized TiO2 surface can selectively change the wettability towards contacting liquids upon visible light illumination due to a photo-induced voltage across external manipulation of liquid and the underlying surface. The photo-induced wettability change of our surfaces enables the liquid droplet motion upon illumination. For more information, see “Visible light guided manipulation of liquid wettability on photoresponsive surfaces ”, Nature Communications, 2017, 8,14968. DOI:10.1038/ncomms14968.