Stable functional surfaces with reversibly switchable wettability have recently been developed for the continuous separation of oil–water mixtures. This article proposes a facile method to fabricate superhydrophobic surfaces on copper meshes by combining poly­(dimethylsiloxane) and graphene. The superhydrophobic surface can dramatically switch to a superhydrophilic state under O2 plasma etching and recover to a superhydrophobic state after laser etching to achieve unidirectional transport of oil or water. The surface had a high separation efficiency and favorable reusability in oil–water separation. In addition, the superhydrophobic surfaces demonstrated not only outstanding stability, including an anticorrosion ability, anti-UV exposure ability, oil contamination resistance, and abrasion resistance, but also an excellent self-healing ability after flame treatment. This research opens a novel avenue for the design of stable materials with reversible wettability that may have promising potential applications in microfluidics, wastewater purification, oil-spill cleanup, and quick, low-cost realization of self-healing materials in situ using operations that can be easily scaled and automated.

Nickel‐coated multiwalled carbon nanotubes (Ni‐MWNT) were prepared by electroless deposition with ultrasonic vibrations. The morphologies and components were characterized by scanning electron microscope and energy dispersive spectroscopy. Two types of fillers, multiwalled carbon nanotubes (MWNT) and Ni‐MWNT, were blended with poly(phthalazinone ether sulfone ketone)s (PPESK) by the solution‐mixing method, respectively. The electrical conductivity and microwave absorbing properties of the composites were investigated. The results show that Ni‐MWNT/PPESK composites have relatively lower electrical resistivity values than MWNT/PPESK, and in both cases the decrease in electrical resistivity indicates a similar percolation transition behavior in the same MWNT content region. Moreover, as MWNT loading is 5 parts per hundred parts of resin (phr), Ni‐MWNT/PPESK composite has the wider frequency region (9.5–13.5 GHz) of the reflection loss (RL) less than −10 dB and the lower minimum value of RL (−27.5 dB) compared with MWNT/PPESK. The better microwave absorption properties can be attributed to the improved dielectric and magnetic properties of the fillers. A good correlation between electrical conductivity and microwave absorption was found for MWNT/PPESK composites. In addition, tensile test and thermogravimetric analysis indicate that introducing Ni‐MWNT into PPESK is favorable for the improvement of the mechanical properties and high temperature stability of the composites. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Fog collection plays an important role in alleviating the global water shortage. Despite great progress in creating bionic surfaces to collect fog, water droplets still could adhere to the microscale hydrophilic region and reach the thermodynamic stable state before falling, which delays the transport of water and hinders the continuous fog collection. Inspired by lotus leaves and cactuses, we designed a Janus membrane that functions to both collect fog from the air and transport it to a certain region. The Janus membrane with opposite wettability contains conical microcolumns with a wettability gradient and hydrophilic copper mesh surface. The apexes of conical microcolumns are superhydrophobic and the rest are hydrophobic. The fog droplets were deposited, coalesced, and directionally transported to the bottom of the conical microcolumns. Then, the droplets unidirectionally passed through the membrane and flowed into the water film on the surface of the copper mesh. The asymmetric structural and wettability merits endow the Janus membrane with an improved fog collection of ∼7.05 g/cm 2 /h. The study is valuable for designing and developing fluid control equipment in fog collection, liquid manipulation, and microfluidics.

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