Thin-film composite membranes based on hyperbranched poly(ethylene oxide) for CO2/N2 separation

Cross-linked amorphous poly(ethylene oxide) (XLPEO) is one of the leading membrane materials for post-combustion CO2 capture. For example, XLPEO prepared from poly(ethylene glycol) methyl ether acrylate (PEGMEA) exhibited CO2 permeability of 570 Barrer and CO2/N-2 selectivity of 41 at 35 degrees C. However, these XLPEOs cannot be dissolved in coating solutions, making it impossible to be fabricated into thin-film composite (TFC) membranes using state-of-the-art manufacturing processes. In this study, we synthesized high molecular weight yet soluble HPEO via atom transfer radical polymerization (ATRP). These polymers were thoroughly characterized and compared with XLPEO, including thermal transitions, free volumes, and pure-gas sorption and permeation properties. A polymer with the best combination of CO2 permeability (540 Barrer) and CO2/N-2 selectivity (43) was fabricated into defect-free TFC membranes with a thickness as thin as 506 +/- 44 nm. When challenged with simulated flue gas containing water vapor at 35 degrees C for over 100 h, the membrane shows stable CO2 permeance of 850 GPU and CO2/N-2 selectivity of 37, comparable to the leading commercial membranes for carbon capture.

Automated summary

Cross-linked amorphous poly(ethylene oxide) (XLPEO) is a leading membrane material for post-combustion CO2 capture. In this study, high molecular weight yet soluble HPEO was synthesized via atom transfer radical polymerization (ATRP) and fabricated into defect-free thin-film composite (TFC) membranes with excellent performance. The membranes showed stable CO2 permeance and CO2/N-2 selectivity under simulated challenge.