(45h) Pushing the limit of CO2 permeance of thin-film composite membranes based on amorphous poly(ethylene oxide) (aPEO)

Mixed matrix materials (MMMs) containing nanofillers dispersed in polymer matrices have shown superior CO2/N2 separation performance for post-combustion carbon capture. However, the fabrication of thin film composite (TFC) membranes containing a defect-free selective layer (< 500 nm) is challenging due to interfacial incompatibility between polymers and nanofillers. Herein, we successfully synthesized high molecular weight amorphous poly(ethylene oxide) (aPEO, 450 kDa) via atom transfer radical polymerization (ATRP) and fabricated TFC membranes based on the gutter layer of polydopamine (PDA) modified polydimethylsiloxane (dPDMS). The membranes exhibited CO2 permeance of 630 GPU and CO2/N2 selective of 53 at 22 oC. Furthermore, highly permeable UiO-66-NH2 nanoparticles (45 - 85 nm) and liquid polyethylene glycol dimethyl ether (PEGDME, 240 Da) can be incorporated in the aPEO to improve CO2 permeance while retaining CO2/N2 selectivity. The additives also have excellent compatibility with aPEO, achieving good membrane uniformity. For example, adding 10 wt% UiO-66-NH2 nanoparticles increases CO2 permeance from 630 to 1700 GPU while increasing CO2/N2 selectivity to 62; incorporating 40 wt% PEGDME into the selective layer comprising aPEO and UiO-66-NH2 dramatically increases CO2 permeance from 1700 to 3000 GPU while remaining CO2/N2 selectivity at 60. We will elucidate the structure/property relationship in this series of membranes, and their mixed-gas testing results will be discussed.