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Wettability patterns have significant application potential in liquid transportation and water collection. Plasma hydrophilization is high-efficient and less-destructive, and has been widely used for preparing wettability patterns. However, the plasma-treated surfaces tend to recover to its original wettability, causing invalidation of the patterns. As a green treatment method, boiled water treatment could construct nanostructures, which is favorable for hydrophilicity-retaining; while the hydrophilization effect of plasma treatment would promote the reaction. Therefore, it should be possible to combine plasma and boiled water treatments to prepare long-lasting wettability patterns. In this paper, superhydrophobic aluminum surfaces were modified by plasma jet followed by boiled water treatment. The time stability, microstructures and chemical compositions of the treated surfaces were investigated by testing contact angles, scanning electron microscope, X-ray diffractometer, and X-ray photoelectron spectroscopy. The surfaces treated by plasma jet and boiled water could retain superhydrophilicity for a long time under various storage conditions, including normal ambient, high temperature or high humidity. On the basis of this technique, long-lasting patterns could be prepared on different metal substrates. The green method proposed is expected to have promising application potential in fabricating wettability patterns and lab-on-chip devices, especially for those used in severe conditions. Unlabelled Image • Long-lasting water/oil wettability patterns are prepared on metal substrates. • The patterns show good time stability under high temperature/humidity. • The patterns are obtained by using plasma and boiled water to modify substrates. • The modification method is reversible. [ABSTRACT FROM AUTHOR]

Oil/water separation has attracted more attention with the dramatic increasing of oil spill accidents and arbitrarily discharged oily industrial water. However, many reported materials with controllable wettability for on-demand oil/water separation of both heavy and light oil/water mixtures involve complicated devices and dangerous fabrication processes. Herein, we propose a simple, environmentally friendly and high-efficient method to fabricate Al mesh with controllable wettability. Heavy oil can be separated with a high efficiency of 99% in oil-removing mode. For light oil, the separation efficiency can also reach up to 99% in water-removing mode. Additionally, surface wettability of the mesh can be conversed from superhydrophobicity to superhydrophilicity by atmospheric pressure plasma jet (APPJ) and heating, thereby realizing continuous bidirectional separation. Therefore, this work provides a facile, green, and efficient way for on-demand oil/water separation and finds a promising solution for oil pollution problems. [ABSTRACT FROM AUTHOR]

This paper proposes a simple, precise, and controllable method to fabricate wettability-gradient surfaces. Combining electrochemical etching and lithography, different micro/nanostructures can be obtained by adjusting the etching time. After being modified by low energy substances, low adhesive superhydrophobic and sticky hydrophobic regions can be obtained on one surface. Based on the obtained adhesion gradient, droplets of different volumes can be controlled to roll off at dissimilar tilted angles via designing sticky hydrophobic tracks with different widths. Directional transportation of water droplets on curve tracks is also realized based on the anisotropic sliding angles parallel and perpendicular to the tracks. [ABSTRACT FROM AUTHOR]

Plasma treatment is a versatile tool for surface modifications, and plasma-induced hydrophilicity has a well-known aging behavior. In this paper, plasma hydrophilization and the subsequent aging behavior of superhydrophobic and hydrophobic surfaces are comparatively investigated. Static water contact angle measurement and X-ray photoelectron spectroscopy show that, compared with the hydrophobic surface, the superhydrophobic surface requires more plasma dose to completely change its wettability even after considering the difference in their initial wettability, and the corresponding aging speed is also obviously retarded. A tentative model based on the surface micro/nanostructures is presented to explain the results. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Tubes are indispensable in our daily life, mechanical engineering and biomedical fields. However, the practical applications of tubes are sometimes limited by their poor wettability. Reported herein is hydrophilization of the tube inner wall by transferred atmospheric pressure plasma (TAPP). An Ar atmospheric pressure plasma jet (APPJ) is used to induce He TAPP inside polytetrafluoroethylene (PTFE) tube to perform inner wall surface modification. Optical emission spectrum (OES) is used to investigate the distribution of active species, which are known as enablers for surface modification, along the TAPP. Tubes’ surface properties demonstrate that after TAPP treatment, the wettability of the tube inner wall is well improved due to the decrease of surface roughness, the removal of surface fluorine and introduction of oxygen. Notably, a deep surface modification can significantly retard the aging of the obtained hydrophilicity. The results presented here clearly demonstrate the great potential of TAPP for surface modification of the inner wall of tube or other hollow bodies, and thus a uniform, effective and long-lasting surface modification of tube with any length can be easily realized by moving the tube along its axis. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Extreme wettability surfaces have attracted more and more attention due to their practical applications, however, few reports have shown a universal method to create surface patterns with extreme wettability on a variety of metals. In this paper, a mask-assisted dual-chemical-processing approach without special modification is used to prepare the extreme wettability patterns on various metal substrates. Fabrication of superhydrophilic-superhydrophobic patterns on five kinds of metal substrates of Al, Ti, steel, Zn and Mg alloy proved the versatility of this method. The extreme wettability patterns prepared by this method were applied to fog harvest and we found the big differences in the collection efficiency of various metal surface patterns. [ABSTRACT FROM AUTHOR]