Flow synthesis of hypercrosslinked polymers with additional microporosity that enhances CO2/N2 separation

Abstract

Hypercrosslinked polymers (HCPs) are typically synthesised over 24 hour batch reactions, limiting productivity rates during scale-up production. Continuous flow synthesis can potentially overcome this limitation. However, the formation of insoluble HCP products, compounded by HCP expansion due to solvent adsorption during synthesis can clog flow reactors. Here, we overcome clogging issues through reactor design and optimisation of synthesis parameters. Using this reactor, we synthesised HCPs via internal, post-, and external crosslinking strategies underpinned by Friedel-Crafts alkylation over various synthesis parameters - residence time, substrate concentration, reagent ratio, and temperature. The space-time-yield (STY) values, a key parameter for productivity rates, of flow synthesis were 32-117 fold higher than those in batch reactions. HCPs produced via internal crosslinking in flow synthesis contained additional microporosity that enhanced CO2/N2 selectivity at 298 K by 850% when compared to HCPs produced in batch reactions. Outcomes from this work could enable high productivity scale-up production of HCPs for post-carbon capture.