NELF predictions of a solubility–solubility selectivity upper bound

Non-equilibrium lattice fluid theory (NELF) is used to evaluate the relationship between solubility and solubility selectivity for glassy polymeric materials. The NELF model provides a priori predictions of gas solubility and solubility selectivity for gas penetrants in glassy polymers without adjustable parameters. The results suggest an upper bound exists on solubility and solubility selectivity. The solubility upper bound depends on gas and polymer material properties through NELF model parameters. The polymer–polymer interaction energy determines the location of the upper bound. The upper bound moves in a favorable direction as polymer cohesive energy density increases and is limited by the highest value achievable in real materials. Furthermore the temperature dependence of solubility and solubility selectivity is predicted by the analysis.