Sorption-enhanced thin film composites with metal-organic polyhedral nanocages for CO2 separation

초록

The atom transfer radical polymerization (ATRP)-based continuous assembly of polymers (CAP) is a promising approach for fabricating thin film composite (TFC) membranes for high flux. Here, we report the preparation of CO2-selective TFC mixed matrix membranes (MMMs) by incorporating different amounts of [Cu-24(m-bdc)(24)(EG)(3)(DMF)(12)] (EG(3)-MOP) nanocages (e.g., 2.5, 5, and 10 wt%) as CO2-philic fillers in a poly(poly(ethylene glycol) dimethacrylate glycol) dimethacrylate (PEG(9)DMA) matrix via the ATRP-based CAP technique. The EG(3)-MOP nanocages are homogeneously distributed in the PEG(9)DMA matrix with a good compatibility between them at up to 5 wt% of EG(3)-MOP nanocages due to the hydrophilic interactions between the triethylene oxide tails of EG(3)-MOP and the PEG of the PEG(9)DMA matrix. Additionally, both CO2 permeance and CO2/N-2 selectivity increased with increasing contents of EG(3)-MOP nanocages up to 5 wt% via a gradual increase in CO2 solubility because of the favorable interaction of both unsaturated Cu(II) sites and triethylene oxide in EG(3)-MOP with CO2. In particular, the EG(3)-MOP/PEG(9)DMA (5/95 wt/wt) TFC-MMM enhanced both CO2 permeance and CO2/N-2 permselectivity relative to those of the pristine PEG(9)DMA membrane by 45 and 50%, respectively, attaining a CO2 permeance of 448 GPU and a CO2/N-2 selectivity of 30. In addition, it exhibited a good CO2/N-2 separation performance under equimolar mixed gas conditions at 35 degrees C, further supporting that our TFC-MMMs fabricated via the ATRP-based CAP technique are attractive for CO2 separation.

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