An Encapsulation-Rearrangement Strategy to Integrate Superhydrophobicity into Mesoporous Metal-Organic Frameworks

Designing materials that combine surface superhydrophobicity, high surface areas, large and uniform pore sizes, and excellent stability is a very challenging area for synthetic chemists. Here, we demonstrate a bioinspired encapsulation-rearrangement strategy to construct superhydrophobic mesoporous metal-organic framework (MOF) systems by selectively modifying the external surface of an internal lattice-rearranged mesoporous MOF. The surface of a defective MOF with limited porosity named AlTz-53 is initially modified by hydrophobic alkyl chains through click reactions. Subsequently, the internal framework undergoes lattice rearrangement upon solvent desorption, leading to a significantly improved internal porosity and material crystallinity. Functionalizing the surface of AlTz-68 with octadecene (AlTz-68-C18) induces superhydrophobicity with a water contact angle of 173.6°. AlTz-68-C18 also exhibits one of the largest Brunauer-Emmett-Teller (BET) surface areas among all reported superhydrophobic framework materials. Furthermore, we illustrate that both superhydrophobic AlTz-68-C18 and the corresponding modified sponge exhibit excellent performance toward oil/water separation. [Display omitted] •Constructing superhydrophobic mesoporous MOFs via encapsulation and rearrangement•Studying click reaction kinetics and the corresponding porosity and hydrophobicity•Enhanced chemical stability after 6-month exposure to humid environments•MOF@sponges show excellent performance toward water/oil separation Wetting is a common phenomenon widely observed in nature. For example, hydrophobic gates are observed in ion channels and nanopores of cell membranes to control ion transportation. Inspired by nature, materials scientists have developed various superhydrophobic materials with special functions for widespread applications. However, existing coating methods for fabricating superhydrophobic surfaces are mainly limited to nonporous or microporous materials. It is still a big challenge to design porous materials combining superhydrophobicity, high surface area, and large pore sizes. Here, we successfully integrated superhydrophobicity into a mesoporous metal-organic framework system without losing internal porosity. The encapsulation-rearrangement strategy reported in the work greatly expands the possibilities of constructing superhydrophobic materials with high porosity for numerous applications associated with energy and environment. A metal-organic framework (MOF) mate