LAUSR

Abstract Gas separation based on membrane technology can possibly be used to offset the greenhouse effect because of its high energy efficiency and low cost. To achieve commercialization, it is essential that the gas-separation membrane demonstrates high performance and scalability. Here, we first report the room-temperature, one-pot process for CO2 capture membranes based on the synthesis of a graft copolymer comprising of poly(ethylene-alt-maleic anhydride) (PEMA) main chains and poly(propylene glycol) (PPG) side chains. As confirmed by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (1H NMR) spectroscopy, the PEMA-g-PPG synthesis was based on the complete reaction (100% conversion) of O-(2-aminopropyl)-O′-(2-methoxyethyl) polypropylene glycol (AMPPG) with PEMA in butanol (BuOH) at room temperature. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) revealed that the PEMA-g-PPG graft copolymer exists in an amorphous rubbery state with a bimodal microstructure. Without any post-treatment, the as-synthesized PEMA-g-PPG in BuOH was directly coated onto a microporous polysulfone support to form thin-film composite membranes. The membrane exhibited high selectivity (i.e. 82.6 for CO2/N2 and 26.8 for CO2/CH4) and good CO2 permeability (99.1 Barrer), outperforming conventional PEBAX block copolymer membranes. CO2 uptake measurements confirmed enhanced CO2 permeation resulting from the improved solubility of CO2 in PEMA-g-PPG compared with those of neat PEMA and PEBAX. The PEMA-g-PPG membrane could be commercially feasible owing to its simple coating process, low cost, high selectivity, and scalability.