A novel superhydrophilic and underwater superoleophobic polyacrylamide (PAM) hydrogel‐coated mesh is successfully fabricated in an oil/water/solid three‐phase system. Compared to traditional oleophilic materials, the as‐prepared hydrogel‐coated meshes can selectively separate water from oil/water mixtures with the advantages of high efficiency, resistance to oil fouling, and easy recyclability.

Biological organisms with super-hydrophobic properties, such as lotus leaves, [1] cicada's wings, [2] water strider's legs, [3] and desert beetle's backs [4] always give us inspiration to design and create novel interfacial materials. Learning from nature, fabrication of micro/nanohierarchical structures and chemically modification with low surface free-energy materials provide effective solutions in obtaining super-hydrophobic interfaces.[5-9] However, superoleophobic interfaces, which display apparent contact angles with oil greater than 1508 and low hysteresis, are highly dependent on modification of fluorinated materials, [10][11][12][13][14][15] resulting in a cumbersome situation when exploring new materials. As previously reported, nearly all efforts were focused on the design and preparation of materials, that is, the control of a single phase, although the interfacial properties usually involve the interactions of two or more phases.[16] Therefore, new strategies to fabricate superoleophobic interfaces remain a challenge.As far as we are aware, examples from nature in air rather than in water environments have attracted most attention from biomimetic research on self-cleaning effect. For example, seabirds, rather than fish, are endangered by pollution from oil during a shipwreck. Boats are contaminated by plankton, while fish can keep their body clean in water. The interesting phenomenon of fish keeping their surfaces clean in oil-polluted water, a new superoleophobic model, inspires us to a novel strategy in designing superoleophobic interfaces. This bioinspired superoleophobic interface with low affinity for oil drops is better than traditional approaches commonly used, which employ surfactant solutions to aid in the removal of oils from the surfaces. [17]