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A triptycene-based diamine, 1,3,6,8-tetramethyl-2,7-diamino-triptycene (TMDAT), was used for the synthesis of a novel solution-processable polyamide obtained via polycondensation reaction with 4,4′-(hexafluoroisopropylidene)bis(benzoic acid) (6FBBA). Molecular simulations confirmed that the tetrasubstitution with ortho-methyl groups in the triptycene building block reduced rotations around the C–N bond of the amide group leading to enhanced fractional free volume. Based on N2 sorption at 77 K, 6FBBA-TMDAT revealed microporosity with a Brunauer–Emmett–Teller (BET) surface area of 396 m2 g−1; to date, this is the highest value reported for a linear polyamide. The aged 6FBBA-TMDAT sample showed moderate pure-gas permeabilities (e.g., 198 barrer for H2, ~109 for CO2, and ~25 for O2) and permselectivities (e.g., αH2/CH4 of ~50) that position this polyamide close to the 2008 H2/CH4 and H2/N2 upper bounds. CO2–CH4 mixed-gas permeability experiments at 35 °C demonstrated poor plasticization resistance; mixed-gas permselectivity negatively deviated from the pure-gas values likely, due to the enhancement of CH4 diffusion induced by mixing effects. [ABSTRACT FROM AUTHOR]

We propose hydroxyl-functionalized polytriazole as a precursor for the preparation of highly crosslinked membranes and carbon molecular sieves (CMS) for gas separation. We studied the effect of the treatment temperature on the chemical structure and gas separation properties. A progressing crosslinking structure was formed when polytriazole films were treated in the range of 300–400 °C. Above 425 °C, CMSs with multi-layered nitrogen-graphene-like structures were obtained. The CO 2 permeability increased by increasing the temperature, while the CO 2 /CH 4 selectivity was maintained. Permeability increases up to 37-fold compared to the untreated polymer film were obtained, aligned with a CO 2 /CH 4 selectivity of 75. The single-gas CO 2 permeability vs. CO 2 /CH 4 selectivity data obtained for films treated at 475 and 550 °C are among the highest reported in the literature. Moreover, the mixed gas performance of these membranes is far above previously reported CO 2 /CH 4 data plotted as mixed-gas trade-off curves, demonstrating the potential of polytriazole materials for these applications. [Display omitted] • Thermally treated OH-polytriazole as starting material for gas separation. • Crosslinked polytriazole by treatment between 300 and 400 °C. • Multi-layered nitrogen-graphene-like structures formed above 425 °C. • Single gas CO 2 /CH 4 selectivity 75 with permeability 2470 Barrer. • Mixed gas CO 2 /CH 4 selectivity 74 with permeability 1360 Barrer. [ABSTRACT FROM AUTHOR]