UV-crosslinked poly(PEGMA-co-MMA-co-BPMA) membranes: Synthesis, characterization, and CO2/N2 and CO2/CO separation

A series of CO2-philic terpolymers were prepared by free radical polymerization using three monomers, poly(ethylene glycol) methyl ether methacrylate (PEGMA), methyl methacrylate (MMA), and 4-hydroxybenzophenone (BPMA), to develop CO2/N2 and CO2/CO separation membranes. The terpolymers, poly(PEGMA-co-MMA-co-BPMA) (PMB), were cast into thin precursor films, which were then crosslinked by a UV-induced photochemical reaction between benzophenone and the alkyl group to produce crosslinked membranes (X-PMB). The gas permeabilities of the X-PMB membranes were influenced by the PEGMA content due to increased CO2 solubility by the polar ether groups of PEGMA. As the content of PEGMA was increased from 60 to 90 wt%, the permeability of CO2 increased from 49.7 to 110.7 barrer. The permeabilities of CO and N2 also increased from 1.92 to 3.68 barrer and from 1.01 to 2.21 barrer, respectively. X-PMB9 with 90 wt% of PEGMA showed the best performance, where CO2 permeability, CO2/N2 selectivity, and CO2/CO selectivity were 110.7 barrer, 49.9, and 30.1, respectively. This membrane performance is comparable to or better than that of a commercially available membrane material, PEBAX, indicating that the X-PMB could be usefully applied to CO2 separation membranes in carbon capture and utilization.