Carbon dioxide/ethane mixed-gas sorption and dilation in a cross-linked poly(ethylene oxide) copolymer

Mixed-gas CO(2)/C(2)H(6) sorption and dilation in a cross-linked poly(ethylene oxide) copolymer were studied at temperatures ranging from -20 to 35 degrees C. The polymer was prepared by photopolymerization of a solution containing 70 wt.% poly(ethylene glycol) methyl ether acrylate (PEGMEA) and 30 wt.% poly(ethylene glycol) diacrylate (PEGDA). Four different gas mixtures (10, 25, 50 and 70 mol% CO(2)) were considered at operating pressures up to 21 atm. At a given temperature, polymer dilation increased with pressure and CO(2) content. Compared to pure-gas values, CO(2) solubility was higher in the presence of ethane, an effect whose extent increased with decreasing temperature. Ethane solubility in the polymer also increased in the presence Of CO(2) compared to the pure-gas value at T >= 25 degrees C. However, at T <= 0 degrees C, the presence of carbon dioxide initially reduced ethane solubility. As the fugacity of CO(2) in the mixture increased and the polymer dilated, ethane solubility progressively increased, eventually surpassing the pure-gas value. The multicomponent Flory-Huggins model could describe the pure- and mixed-gas data simultaneously, provided that an empirical composition dependence was included in the interaction parameters for T < 25 degrees C. (C) 2010 Elsevier Ltd. All rights reserved.