Development of oil-repellent coatings that are anti-fouling with water alone is highly desirable, yet still challenging. Herein, to address this challenge, we fabricate a slippery oil-repellent hydrogel coating that exhibits oil repellency when exposed in the air as well as underwater. In the air, water wets the slippery oil-repellent hydrogel coating surface completely, while organic liquid drops such as toluene can slide off the water wetted coating surface easily. When immersed in water, the slippery oil-repellent hydrogel coating surface exhibits excellent underwater superoleophobic property with all oil contact angles more than 159° and oil adhesive forces less than 1 μN. The hydrogel coating keeps its oil repellency after long-term outdoor storage, thermal treatment, knife scratching and other treatments. Exploiting its water-attracting and oil-repelling property, the slippery oil-repellent hydrogel coated copper mesh and filter paper are demonstrated as reusable membranes to separate oil–water mixtures with separation efficiency more than 97%.

中文翻译：

---

光滑的拒油水凝胶涂料

迫切需要开发仅用水防污的拒油涂层，但仍具有挑战性。在此，为了应对这一挑战，我们制造了一种光滑的拒油水凝胶涂层，该涂层在暴露于空气和水下时均具有拒油性。在空气中，水会完全润湿光滑的拒油水凝胶涂层表面，而有机液滴（例如甲苯）则很容易从润湿的涂层表面滑落。当浸入水中时，光滑的抗油水凝胶涂层表面表现出优异的水下超疏油性，所有油接触角均大于159°，油粘附力小于1μN。水凝胶涂层在长期户外存放，热处理，刮擦刀子和其他处理后仍保持其拒油性。