Polymerized ionic liquids (PILs) membranes demonstrated good potential for advanced separation potentials. To further improve the gas separation performance of PILs-based membranes, a flexible porous polypyrrolidinium membranes for CO 2 /N 2 separation has been developed through a one-step processing via a facile  ring-openingmetathesis polymerization (ROMP), the resulting porous  polypyrrolidinium membranes showed CO 2 permeability of 209 Barrer  (PCPy-TFSI) and CO 2 /N 2 selectivity of 46.9 (PCPy-PF 6 ). More  importantly, the  prous polypyrrolidinium membranes showed improved  anti-aging performance compared with PIM-1 membranes.  This newly-developed ionic porous polymer membranes will bring new  possibilities to new MMMs technology in the near future