Facile Hydrophobic Polymer Coating of Metal–Organic Frameworks for Insulating Materials with Low Dielectric Constant

We report a gentle, one-pot polymer coating method for metal-organic frameworks (MOFs) utilizing silane coupling chemistry. A polymer composed of styrene-butadiene-styrene (SBS) with alkoxysilyl side groups was coated onto zeolitic imidazolate framework-8 (ZIF-8) and Universitet Oslo-67 (UiO-67) surfaces by simply mixing the MOF and polymer in toluene at room temperature. X-ray photon spectroscopy and N₂ adsorption isotherms suggested that the polymer was immobilized on the MOF surface through the interaction between the metal sites and silyl groups. Polymer surface coverage was enhanced by ball milling while preserving the porosity of the MOFs. The polymer-coated MOFs exhibited higher hydrophobicity, wettability to toluene, and stability in water and acid than those of the uncoated MOFs and the MOFs modified with dodecyltrimethoxysilane.