High-Performance Ultrathin Mixed-Matrix Membranes Based on Adhesive PGMA-g-POEM Comb 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-g-poly(oxyethylene methacrylate)) (PGMA-g-POEM) comb copolymer synthesized via low-cost free-radical polymerization. Owing to its adhesive property and good film-forming ability, the PGMA-g-POEM allows the MMMs to be fabricated into 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 487.7 GPU (958% increase compared with a neat PGMA-g-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 1321.6 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.