Wesynthesizedonequaternaryammoniumpolymericionicliquids(PILs)P[VBTHEA]ClandthreeimidazoliumPILsofP[VEIm]Br,P[VEIm]BF4,P[VEIm]PF6byfree-radicalpolymerizationinsolution.ThesePILswerecharacterizedbyFT-IR,1H-NMR,13C-NMR,TGA,XRDandSEM.TheirCO2adsorptioncapacitiesweremeasuredunderdifferentpressuresandtemperaturesbyconstant-volumetechnique.ItwasobservedthatquaternaryammoniumPILsofP[VBTHEA]ClhavehigheradsorptioncapacityforCO2thanthoseimidazoliumPILs,followingP[VBTHEA]Cl>P[VEIm]PF6>P[VEIm]BF4>P[VEIm]Br,whichmaybeascribedtohigherpositivechargedensityonammoniumcationthanthatonimidazoliumcationandthusstrongerinteractionwithCO2,consistentwiththeresultsfromdual-modeadsorptionmodelthatammoniumPILshavemuchhigherCO2bulkabsorptionthanimidazoliumPILs.CO2adsorptioncapacityofP[VBTHEA]Clis9.02mg/gunder295Kand1bar,whichiscomparabletothatofsomeotherPILs,andismuchhigherthanthatofthecorrespondingILsmonomer.ThesePILshavegoodadsorptionselectivityforCO2overN2andregenerationefficiency.