Cross-linking of poly (ether-block-amide) by poly (ethylene glycol) diacrylate to prepare plasticizing-resistant CO2-selective membranes

Abstract

In this study, poly (ethylene glycol) diacrylate (PEGDA) comprising CO2-philic ether oxygen groups was used as a cross-linking agent to develop plasticizing-resistant poly (ether-block-amide) (Pebax-1657) composite membranes with high performance for CO2 separation. The effect of PEGDA concentration on the structure and properties of the membranes as well as gas separation efficiency was investigated. The FT-IR analysis and swelling measurements confirmed the influential role of PEGDA as the cross-linking agent in the prepared membranes. Based on the performed characterization analyzes, it was found that the concentration of the cross-linking agent strongly affects the structural and CO2 separation properties of the cross-linked Pebax membranes. By introducing a cross-linking reaction, the tightness and crystallinity of modified Pebax membranes enhanced compared to the uncross-linked Pebax membrane. The DSC analysis indicated the Tg of the prepared Pebax membranes increased from −54.7 °C to −52.45 °C by increasing the PEGDA content. When the PEGDA concentration increased from 0 wt% to 6 wt%, the selectivity of CO2/N2, CO2/CH4, and CH4/N2 enhanced by 294%, 105%, and 92%, respectively, while the gas permeabilities slightly decreased. The cross-linked Pebax-1657 membrane containing 6 wt% of PEGDA surpassed the Robeson’s upper bound and denoted a prosperous separation performance in the case of CO2 separation from CH4 and N2, compared to the uncross-linked Pebax.