Effect of poly(ethylene glycol) molecular weight on CO2/N2 separation performance of poly(amide-12-b-ethylene oxide)/poly(ethylene glycol) blend membranes

Membranes from block copolymer poly (amide-12-b-ethylene oxide) (Pebax1074) and its blends with different molecular weight poly (ethylene glycol) (PEG) (200, 400, 600, 1500, 4600 and 8000) were prepared. The thermal properties and structures of Pebax1074/PEG blend membranes were characterized by DSC and SEM, and the gas permeation properties of CO2 and N-2 were also investigated at different temperatures. For Pebax1074/PEG blend membranes with low molecular weight PEG (M-w <= 600), higher gas permeabilities than Pebax1074 were achieved. The permeability increased with the increase of PEG molecular weight. The addition of low molecular weight PEG resulted in decrease in activation energy of permeation. For Pebax1074/PEG blend membranes with high molecular weight PEG (M-w >= 1500), due to the melt of PEO phase crystals, the gas permeation properties of blend membranes were temperature-dependent, which could be divided into crystalline region, transition region and amorphous region according to two different transition temperatures. PEG molecular weight and operation temperature determined different gas permeation properties of Pebax1074/PEG blend membranes in three regions. The activation energies of permeation in crystalline region were larger than those in amorphous region. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.