A universal approach to turn UiO-66 into type 1 porous liquids via post-synthetic modification with corona-canopy species for CO2 capture

Porous liquids (PLs), an emerging class of liquid materials with permanent porosity and good fluidity, have shown great potential in gas capture and separation. However, directly turning metal?organic frameworks (MOFs) into type 1 PLs via post-synthetic modification (PSM) strategy with corona-canopy species has not been reported till now. Moreover, challenges including reducing the cost and simplifying the synthesis process are daunting. In present study, we propose a universal approach to turn UiO-66 into PLs via post-synthetic modification strategy with core-corona-canopy structure using organosilane (OS) corona and oligomer canopy species. The ionically-tethered canopy species endow UiO-66 with good liquid-like behaviors at room temperature. CO2 and N2 adsorption?desorption behaviors revealed that PLs possessed great potential in CO2 selective adsorption separation. Meanwhile, the enhanced CO2 selective capture sites were determined. As a proof-of-concept, the asprepared UiO-66-liquid-M2070 PL was incorporated into Pebax-1657 polymer matrix to prepare mixed matrix membranes (MMMs). The excellent dispersion ability, porous structures, and corona-canopy species contributed to the enhanced CO2 selective permeation. Therefore, the CO2 permeability and CO2/N2 selectivity of MMM PUiO-66-liquid-50 increased by 396.5% and 81.3%, respectively, compared with that of pure Pebax membrane, showing attracting prospect in membrane separation. Moreover, the generality of this PSM strategy was confirmed using other different types of canopy species. Remarkably, this PSM strategy could be applied to synthesize other types of advanced porous materials (APMs)-based (e.g., covalent organic frameworks (COFs)) PLs by utilizing the rich library of oligomer species, thus undoubtedly advancing the applications of porous liquids in gas storage and separation.

Automated summary

This study introduces a novel method to convert UiO-66 into PLs with great potential in CO2 selective adsorption separation through post-synthetic modification strategy. The mixed matrix membranes prepared from PLs exhibited enhanced CO2 permeability, showcasing an attractive prospect in membrane separation. The generality of the post-synthetic modification strategy was confirmed, allowing for the synthesis of PLs based on other advanced porous materials.