Fabrication of biomimetic superhydrophobic melamine sponge via oxidation-mediated metal-phenolic networks for oil/water separation

Superhydrophobic/superoleophilic sponges with hierarchical biomimetic surfaces hold great potential for application in oil/water separation. However, the process of coupling hierarchical rough structures with hydrophobic chemical groups to fabricate biomimetic superhydrophobic surfaces remains tedious and complicated, making industrial promotion challenging. Herein, we developed an oxidation-mediated kinetic strategy to fabricate a biomimetic interlayer on melamine sponge (MS) skeletons. Initially, the precursor tannic acid-Fe II (TA-Fe II ) complexes were oxidized to interface-active TA-Fe III species. This transformation facilitated the controlled deposition of a biomimetic coating with precise spatial and temporal regulation. Subsequently, octadecylamine modification was employed to impart superhydrophobic properties to the functionalized sponge. Compared with the TA-Fe III mediated hydrophobic sponge by discrete assembly and layer-by-layer self-assembly, the intermediate layer generated by continuous oxidative growth of the TA-Fe II system features a hierarchical spherical rough morphology and demonstrates superior hydrophobicity, achieving a water contact angle of 165°. In addition, the modified sponge exhibits excellent hydrophobic properties in a wide range of application environments, and has excellent oil/water separation performance in both static and dynamic operating environments. It is expected that this simple and effective biomimetic superhydrophobic coating preparation process can provide a reference for applications based on superhydrophobic surfaces.