Effect of End Groups and Grafting on the CO2Separation Performance of Poly(ethylene glycol) Based Membranes

Rubbery membranes have attracted significant attention for the CO 2 /light gas separation due to their relative high permeability and high solubility selectivity. This work reports universal strategies to tailor CO 2 permeability and CO 2 /light gas permselectivity via blending or grafting of poly(ethylene glycol) (PEG) derivatives into or onto organic–inorganic membrane (OIM) substrates. A PEG derivative is blended into the substrate which contains inorganic siloxane networks and poly(ethylene oxide) segments followed by thermal grafting. Ultrahigh CO 2 permeability (982 barrer at 45 °C) is achieved via physical blending, while extremely high CO 2 permeability (1840 barrer at 45 °C) is obtained after chemical grafting. Neither of these two modification methods shows the loss of CO 2 /H 2 and CO 2 /N 2 selectivity compared to the substrate. Melting and crystallization behaviors of this PEG derivative are believed to significantly affect the overall gas permeation performance. All the features make these OIMs promising membrane materials for CO 2 capture.