A slippery hydrogel coating with durable oil-repellent property and self-regeneration capacity

Traditional lubricant impregnated surfaces usually required fluorinated lubricants to achieve slippery oil repellency, but the lubricants infused were expensive and toxic and also suffered from limited stability because of their migrating, evaporating, and leaking during use. Herein, to address this issue, we fabricated a durably fluorine-free slippery oil-repellent hydrogel coating using water as the lubricant. Due to its enhanced water-binding affinity, water could wet the hydrogel completely and form a hydrated-water layer on the surface. The hydrated water layer could act as a lubricant to repel foreign oils, which allowed the hydrogel to display slippery oil-repellency in air, exhibit superoleophobicity underwater, and resist oil fouling upon oil immersion.The hydrogel kept its oil-repellent properties after mechanical tests as well as thermal and freezing treatments,demonstrating its durability. Thanks to its moisture absorption, the water lubricant layer could self-regenerate upon the lubricated water layer depletion through exposure to a humid environment. Exploiting it is water-attracting and oil repellency, the hydrogel coating was demonstrated as a versatile platform for oil/water separation, polymer/water separation, drag-reduction, and antifogging.

A Self‑Regenerable Fiber Sloughing Its Heavy Metal Skin for Ultrahigh Separation Capability

Developing efficient separation materials for recovering metal resources from aqueous environments is crucial for the sustainable water–food–energy nexus,which addresses the interdependence between energy production,water production,and energy consumption.Various material-based separation processes have demonstrated outstanding performance.However,electric energy and chemicals are used to frequently replace the separation materials used in such processes owing to their short life span.This study presents a methodology for designing the self-regenerable fiber(SRF)according to the types of metals through a self-regeneration model.The SRF can semi-permanently recover the metal resources from water through a repetitive adsorption–crystallization–detachment process of metal ions on its surface.The ionic metal resources are adsorbed and crystallized with the counter-anions on the SRF surface.Next,the metal crystals are self-detached from the SRF surface by the collision between the crystals and curvature and non-sticky surface of the SRF.Thus,a module containing the SRF maintains its metal recovery capability even during continuous injection of the metal solution without its replacement.These findings highlight the significance of interfacial engineering and further guide the rational design of energy/environmentally friendly resource recovery modules.