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

Abstract

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.

Polymer Networks: From Plastics and Gels to Porous Frameworks

“…While many MOFs show limited thermal and chemical/hydrolytic stability, several classes of hydrolytically stable MOFs have been developed, such as UiO‐66 formed from ZrCl 4 and terephthalic acid . Moreover, creating hybrid materials from flexible polymers and crystalline MOFs has arisen as an intriguing way to increase the stability and processability of these materials . As one example, polymer–metal–organic frameworks (polyMOFs) can be synthesized from metal ions and flexible polymer ligands with aromatic dicarboxylic acids in their backbone.…”

“…[212] Moreover, creating hybrid materials from flexible polymers and crystalline MOFs has arisen as an intriguing way to increase the stability and processability of these materials. [213][214][215][216] As one example,p olymer-metal-organic frameworks (poly-MOFs) [217][218][219][220] can be synthesized from metal ions and flexible polymer ligands with aromatic dicarboxylic acids in their backbone.P olyMOFs can possess high crystallinity,h igh porosity,and exceptional water stability.…”

Polymer/Metal Organic Framework (MOF) Nanocomposites for Biomedical Applications

“…Water stability was indeed increased as the hydrophobic PDMS coating prevented water molecules from interacting with the metal ions. Pastore et al reported a different approach that is worth mentioning, although not exploitable for drug delivery application [109]. In this work, poly(amic acid) was conjugated to MOF crystals using post-synthetic ligand exchange ( Figure 10).…”

Polymernetzwerke: Von Kunststoffen und Gelen zu porösen Gerüsten

“…Während die thermische, chemische und Hydrolysebeständigkeit viele MOFs begrenzt ist, wurden einige Klassen hydrolysebeständiger MOFs entwickelt, wie UiO‐66, das aus ZrCl 4 und Terephthalsäure gebildet wurde . Darüber hinaus hat sich die Herstellung von Hybridmaterialien aus flexiblen Polymeren und kristallinen MOFs als interessante Möglichkeit erwiesen, die Stabilität und Verarbeitbarkeit dieser Materialien zu verbessern . Als ein Beispiel dafür stehen Polymer‐MOFs (polyMOFs), die aus Metallionen und flexiblen Polymerliganden mit aromatischen Dicarbonsäuren in ihrem Gerüst synthetisiert werden können.…”

“…[212] Darüber hinaus hat sich die Herstellung von Hybridmaterialien aus flexiblen Polymeren und kristallinen MOFs als interessante Mçglichkeit erwiesen, die Stabilitätu nd Verarbeitbarkeit dieser Materialien zu verbessern. [213][214][215][216] Als ein Beispiel dafürs tehen Polymer-MOFs (polyMOFs), [217][218][219][220] die aus Metallionen und flexiblen Polymerliganden mit aromatischen Dicarbonsäuren in ihrem Gerüst synthetisiert werden kçnnen. PolyMOFs kçnnen eine hohe Kristallinität, eine hohe Porositätund eine außergewçhnliche Wasserbeständigkeit aufweisen.…”