Xudong Hu1, Jianbin Tang1, Youqing Shen2, and Maciej Radosz3. (1) Department of Chemical and Petroleum Engineering, University of Wyoming, 1000 E. University Ave, Laramie, WY 82071, (2) Department of Chemical and Petroleum Engineering, University of Wyoming, 1000 E University Ave., Laramie, WY 82071, (3) Department of Chemical & Petroleum Engineering, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071
Polyethylene glycol (PEG) is grafted onto ionic polymers poly[p-vinylbenzyltrimethylammonium tetrafluoroborate] (P[VBTMA][BF4]) and poly[2-(methylacryloyloxy)ethyl-trimethylammoniumtetrafluoroborate] (P[MATMA][BF4]). Membranes made of P[VBTMA][BF4]-g-PEG and P[MATMA][BF4]-g-PEG are found to be CO2 selective for CO2/CH4 and CO2/N2 separations, and less brittle than those made of pure (P[VBTMA][BF4]) and P[MATMA][BF4]. At the same permeability, they are found to have higher CO2/CH4 and CO2/N2 selectivity than the previous polymeric membranes. The selectivity of such PEG-grafted ionic membranes is primarily due to the solubility differences, not the diffusivity differences.