Figure 4.

(a) Experimental CH₄ solubility coefficient vs. CH₄ fugacity and (b) CO₂ solubility coefficient vs. CO₂ fugacity of 6FDA-mPDA. The inset graphs report the solubility coefficient behavior of CH₄ and CO₂ at various equilibrium concentrations—these curves were predicted using the dual-mode sorption model extended to mixtures (DMS-mix) [35] and the pure-gas DMS sorption parameters (Table S1). Note that the feed mixture concentration is the parameter for the experimental data in (a,b), whereas the concentration at equilibrium is the parameter for the DMS-mix predictions (insert graphs); hence, the comparison between experimental data and predictions is qualitative (i.e., the DMS-mix curves guide the reader through the data).