To search for robust CO2 capture materials, two types of ionic liquids, namely, (p-vinylbenzyl)trimethylammonium tetrafluoroborate ([VBTMA][BF4]) and (p-vinylbenzyl)trimethylammonium hexafluorophosphate ([VBTMA][PF6]), were synthesized and immobilized onto a mesoporous silica (meso-silica) support by the surface-initiated atom-transfer radical polymerization (SI-ATRP) method. The prepared sorbents meso-SiO2P[VBTMA][BF4] and meso-SiO2P[VBTMA][PF6] were well-characterized. Their adsorption behaviors toward CO2 from simulated flue gases at different pressures were investigated using an adsorption column. Based on a simulated flue gas containing 10 vol % CO2 at 30 degrees C, the highest CO2 adsorption capacity of meso-SiO2P[VBTMA][BF4] was 0.4025 mmol g1, whereas the corresponding value for meso-SiO2P[VBTMA][PF6] was 0.3793 mmol g(-1). Compared with pure poly(ionic liquid)s, the existence of a meso-silica core improves the CO2 capture capacity. Furthermore, the presence of vapor can improve the CO2 capture capacity. However, an increase in temperature inhibits the CO2 capture capacity, implying that the nanocomposites should preferably be used at low temperature.