Breaking barriers: Unleashing CO2 selectivity with ultrathin poly(1,3-dioxolane) composite membranes produced by continuous assembly of polymers

Abstract

Carbon dioxide (CO2) emissions have continued to rise with the sustained reliance on fossil fuels. One leading solution to capturing CO2 emissions is ultrathin film composite (UTFC) membranes due to their cost-efficiency and relatively low environmental impact. On-going efforts to overcome the challenges of practical membrane technology have included increased gas selectivity and robustness toward the low partial pressure of CO2 emitted from coal-fired power stations. Poly(1,3-dioxolane) (PDXL) has been discovered to have exceptional CO2/N2 selectivity outperforming similar high-polar polymers including poly(ethylene oxide) (PEO), PolyActive™, and Pebax®. However, designing as a composite membrane with PDXL has never been accomplished due to a vital challenge of poor interlayer adhesion, and this has restricted its further advancements. The surface-confined Continuous Assembly of Polymers (CAP) technology can be used to overcome the issue of poor interlayer adhesion; however this strategy needs to be modified to ensure all layers are covalently linked. In this study, we synthesized crosslinkable poly(1,3-dioxolane) dimethacrylate (PDXLDMA) and fabricated UTFC membranes via a revised CAP process. The resulting PDXL-based UTFC membrane demonstrated the highest CO2/N2 selectivity (71.3) ever achieved under dry conditions, while maintaining a gas permeance of above 1000 GPU. The modified CAP process preserved PDXL's inherent properties in the UTFC membrane and demonstrated excellent chemical and mechanical strength through crosslinked layers and covalent bonding of the multilayer structure.