High-performance ultrathin mixed-matrix membranes based on an adhesive PGMA-co-POEM comb-like copolymer for CO₂ capture

We report high-performance mixed-matrix membranes (MMMs) based on amine-functionalized UiO-66 (UiO-66-NH₂) nanoparticles dispersed in a poly(glycidyl methacrylate-co-poly(oxyethylene methacrylate)) (PGMA-co-POEM) comb-like copolymer synthesized via low-cost free-radical polymerization. Owing to its adhesive properties and good film-forming ability, PGMA-co-POEM allows the MMMs to be fabricated as ultrathin film composite membranes without voids or defects. Additionally, the formation of covalent bonds between the copolymer and UiO-66-NH₂ particles via an epoxide-amine reaction improves their interfacial compatibility. As the loading of UiO-66-NH₂ fillers increases, a dual transport pathway is formed in the MMMs, significantly increasing the gas permeance. The physicochemical properties and gas separation performance of the MMMs are systematically investigated with respect to the filler loading. A MMM containing 28.6 wt% UiO-66-NH₂ nanoparticles exhibits a CO₂ permeance of 488 GPU (958% increase compared with a neat PGMA-co-POEM membrane) with a moderate CO₂/N₂ selectivity of 31.9. By reducing the thickness of the selective layer to <100 nm, the CO₂ permeance is enhanced to 1320 GPU without any significant loss of selectivity (30.8), which exceeds the target performance required for practical application in the post-combustion CO₂-capture process.