(697b) Carbon Dioxide Sorption in Poly(ionic liquid)s

Poly(ionic liquid)s are a new class polymeric materials having many interesting proeprties. Particularly, they have high and selective and reversible CO2 sorption. The CO2 sorption in poly(ionic liquid)s with different structures at low pressures is investigated, indicating that the CO2 sorption capacities (mL(STP)/mL) of the poly(ionic liquid)s with different cations are in a sequence of ammonium > pyridinium > phosphnium > imidazolium, and those with different anions are in a sequence of BF4 > PF6 >> bis(trifluoromethylsulfonyl)imide (Tf2N). The poly(ionic liquid) with a polystyrene backbone has higher CO2 sorption capacity than that with a polymethylmethacrylate backbone, and the poly(ionic liquid) with long substituents on the cation has higher CO2 sorption capacity than that with short one. Crosslinking decreases the CO2 sorption capacity. Poly[1-(p-vinylbenzyl) trimethylammonium tetrafluoroborate] (P[VBTMA][BF4]) has the highest CO2 sorption capacity of 10.7 mL(STP)/mL at 22 °C. The CO2 sorption in the poly(ionic liquid)s fits the Dual-mode Model very well, suggesting that the CO2 sorption consists of the dissolution in polymer matrix and the Langmuir sorption in microvoid.