A synergistic strategy via the combination of multiple functional groups into membranes towards superior CO2 separation performances

Membrane-based technology for CO2 separation offers great potentials in environment and energy-related fields, and developing high-performance membranes is the key to improve the competitiveness of membrane process. In this work, a novel alternative strategy to enhance membrane performance was suggested via the combination of multiple functional groups into membranes, by which not only could circumvent the limitations of single functional group used, but also could achieve the synergistic effects of different functional groups. Thus, poly(diallyldimethylammonium carbonate-co-vinylamine) (P(DADMACA-co-VAm)) random copolymer containing primary amino groups, carbonate groups and quaternary ammonium groups was designed and synthesized. Then P(DADMACA-co-VAm)/polysulfone (PSf) composite membranes were developed by a simple solution casting method. Owing to the cooperative interactions of different functional groups, a notably improved gas separation performance of P(DADMACA-co-VAm) membrane was shown compared to polyvinylamine (PVAm) membrane and poly(diallyldimethylammonium carbonate) (PDADMACA) membrane. Furthermore, P(DADMACA-co-VAm) membrane exhibits superior CO2 permeance and CO2/gas selectivity for CO2/N2, CO2/CH4 and CO2/H2 mixed gas, respectively. Last, P(DADMACA-co-VAm) membrane displays favorable long-term stability and resistance to impurities. These results suggest that P(DADMACA-co-VAm) membrane has a great potential in CO2 capture from flue gas, natural gas purification and synthesis gas purification.