3.3.4. Gas Permeability

Blending changes the porosity of film and thus also the gas permeability for different gases [9]. The pure gas permeability and ideal selectivity of AGO/SPEEK films are summarized in Table 1. SPEEK has superior gas permeability performance because of the presence of a polar –SO3H group chain, which interacts with different gas molecules and then improves upon the solubility coefficients with the gas particles [9,35]. Comparative analysis indicates that the gas permeability of GO/SPEEK films decreases slightly due to the consumed –SO3H groups, which is consistent with the results of Xin et al. [36]. Notably, the CO2 permeability of AGO/SPEEK films was significantly increased, while the permeability of O2 or N2 did not change significantly. It was attributed to the presence of –NH2 groups in AGO that have an excellent affinity for CO2. Moreover, the reaction between CO2 and –NH2 groups intensified in the wet state, resulting in increased CO2 permeability of AGO/SPEEK films [34]. Therefore, for both CO2/O2 and CO2/N2, ideal selectivity increased from 7.3 and 22.2 to 12.2 and 29.1, respectively, with increasing AGO composition in the blended films.


**Table 1.** Gas permeability of films for pure gas.
