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.