Covalent “Bridge-crosslinking” strategy constructs facilitated transport mixed matrix membranes for highly-efficient CO₂ separation

Facilitated transport mixed matrix membranes (FTMMMs) separation technology has shown advantages in improving CO₂ recycling efficiency and reducing the environmental impacts associated with carbon emission. The design of FTMMMs is highly dependent on the selection of a compatible combination of polymer and filler. Herein, a novel grafted nanoparticles (GNPs) filler UiO-66-NM@PEG with multiple groups prone to hydrogen bond was designed to alleviate the phase separation and performance degradation caused by filler/polymer poor compatibility. In the GNPs configuration, by employing the coexistence strategy of coupling reaction and covalent bonds, maleic anhydride (MAH) was coupled with the amino group on UiO-66-NH₂ without clogging or cracking, and the generated carboxyl groups can be cross-linked with the hydroxyl groups on the poly (ethylene glycol) (PEG) by covalent bonds. The UiO-66-NM@PEG demonstrated excellent interface compatibility between the filler and matrix phase of UiO-66-NM@PEG/PVDF, which was further convinced by molecular modelling. The resultant UiO-66-NM@PEG/PVDF achieved a simultaneous enhancement of gas permeability (537.6 Barrer) and ideal CO₂/N₂ selectivity (47.8), which surpassed Robenson upper bound. Moreover, the UiO-66-NM@PEG/PVDF has a lasting sustainability over 960 h (40 days), and a valid anti-acid/alkali corrosion resistance in harsh environments. More importantly, UiO-66-NM@PEG can also be well mixed with other mixture matrices such as hydroxy-terminated polydimethylsiloxane (PDMS) and polyether-block-polyamide copolymer (PEBAX) to promote permeability/ideal selectivity up to (724.1 Barrer/21.1) and (307.4 Barrer/31.4). We thus concluded that this rational-design GNPs approach provides a general toolbox for controllable engineering in GNPs whereby enhanced favorable filler/matrix compatibility in FTMMMs with optimized CO₂/N₂ separation properties.