We employ the static version of the mean-field theory to obtain adsorption behavior and solubility coefficients in model polymer matrices. To obtain permeability across the membrane, we employ the dynamic mean-field theory, as described in the Methods section. A sample of the membrane structure is placed between two control volumes. In the source control volume, the density of gas and the composition of the binary mixture is maintained to resemble to the 15% CO 2 and 85% N 2 binary mixture at 1 bar and 35 °C, corresponding to the typical conditions of the flue gas from coal power plants. The equations governing the density flux from one site to another are provided in the Methods section.