Crosslinked polyimides with a pendant piperazinium bromide acting as both the crosslinker and the CO2-philic functional group have been developed. These ionic-group-mediated crosslinked polyimide membranes showed excellent thermal, mechanical and chemical stabilities, as well as high tolerance to plasticization. Unlike other typical crosslinked polymers, the pendant piperazinium-mediaLed cross linked polyimicle membranes displayed high CO2 permeability of 475.5 Barrer, together with high CO2/CH4 (34.5) and CO2/N-2 (18) perrnselecLiviLies. We also demonstrate that the CO2 separation performances of these membranes can be tuned by changing the crosslinking method. (C) 2015 Elsevier B.V. All rights reserved.