(166d) Sol-Gel Processing of Covalent Organic Frameworks

Covalent organic frameworks (COFs) are comprised of organic building blocks stitched together through covalent bonds into periodic extended structures. The high surface area, crystallinity, and stability of COFs makes them exceptional candidates for applications spanning fields from gas storage, separation science, energy storage and catalysis. However, the processing of COFs remains a significant challenge. Current methods for COF synthesis produces insoluble crystalline aggregates and powders which are difficult or impossible to process into films, coatings, or bulk uniform samples of a desired shape and morphology. In this work, we demonstrate a sol-gel route to COF synthesis that produces a homogeneous solution of COF organic building blocks that can be solution processed and subsequently annealed to produce crystalline and homogeneous COF materials of a desired morphology. We show that our method can be used to produce imine COFs as free-standing casted films, monoliths, and extruded shapes with intrinsic hierarchical morphology, excellent crystallinities (Figure 1) and high surface areas. We demonstrate the application of these COF materials as adsorbents and membranes. This work demonstrates a simple and versatile processing route to produce macroscopic, homogeneous, and crystalline COF materials and will significantly advance the development of COFs for various applications.