Polymer-MOF Hybrid Composites with High Porosity and Stability through Surface-Selective Ligand Exchange

Hybrid materials containing organic polymers and metal-organic frameworks (MOFs) have attracted attention for their potential to harness both diverse functionality and high processability, but their fabrication is challenged by incompatibilities of the parent components. The poor solubility of MOFs hinders uniform dispersion throughout a polymer matrix and may cause aggregation that is not only detrimental to the permeability of substrates, but also limits the structural integrity of the polymer. Meanwhile, polymer chains can block or penetrate the porous structures and compromise MOF functionality by reducing surface area and pore size. We report a versatile method of covalent hybridization through post-synthetic ligand exchange to form a cross-linked polymer-MOF composite. The resulting network structure allows for the formation of robust, monolithic composites with variable MOF loadings that may exceed 80% wherein ligand exchange is limited to surface sites so as to fully preserve MOF surface area and porosity. The synthesis can be performed from a diverse set of inexpensive starting materials, encouraging the design of new functional materials across a wide range of applications.