Covalent Organic Frameworks (COFs) are crystalline, porous organic materials with applications including catalysis, energy storage, water treatment, and drug delivery. However, challenges in both synthesis and processing limit their development for various applications, and methods for preparing COF composites either produce poorly mixed materials or require multi-step synthesis procedures. In this presentation, we present novel synthesis and processing strategies that enable the preparation of COF foams, gels, aerogels, and composites and demonstrate a variety of associated applications. First, we demonstrate a novel and simple approach to synthesize pure crystalline COF aerogels. In contrast to previously re-ported methods for fabricating COF foams and aerogels, our method does not require any additives that remain in the final COF or acids which can degrade or disrupt the COF crystallinity. In brief, our method involves using dimethyl sulfoxide (DMSO) as the reaction solvent and 6M acetic acid as the catalyst. We tested this solvent and catalyst combination for the synthesis of six different imine COFs. These macroscopic COF aerogels retained the shape of the reaction vial, feature hierarchical micropores and mesopores, and show excellent adsorption capacities. We demonstrated that these COFs could be easily effectively implemented in adsorption and decontamination applications. Next, as a one-step method to produce COF composites, we utilized metal oxide nanoparticles as catalysts for the preparation of imine COFs, taking advantage of the strong Lewis acidity of a wide range of metal oxides, including Nb2O5, RuO2, TiO2, and Mn2O3. We produced COFs in high yield, and the final materials consisted of COFs with metal oxides intimately dispersed and embedded in the COF. This provides a simple one-step approach to COF composites with applications in separations, remediations, and catalysis.

Synthesis and processing of COF gels, aerogels, and composites for remediation and separations

ACS Fall 2021

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