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Abstract Advancements in the performance and properties of ionenes can be achieved via rational molecular design strategies which combine structural elements of ionic liquids (ILs) and high‐performance polymers. The use of imidazole‐amine molecules with asymmetric reactivity has enabled the synthesis of new bis(imidazole) diimide monomers which are then polymerized via the Menshutkin reaction, followed by anion exchange to various molecular species well known in the IL literature. In this work, three types of imidazolium polyimide‐ionene backbones were synthesized starting from 1‐(3‐aminopropyl)imidazole and pyromellitic dianhydride (PMDA) or 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) or from 1‐(4‐aminophenyl)imidazole and 6FDA, with these monomers then reacted withpara‐dichloroxylene. The Cl⁻anions on the resultant ionenes were then exchanged with one of six molecular anions yielding a total of 18 distinct polymer compositions. The functional groups present within the cationic backbone as well as the anion type were observed to strongly influence both the thermal and organizational properties of these new ionenes. © 2019 Society of Chemical Industry 

ABSTRACT A new series of six imidazolium‐based ionenes containing aromatic amide linkages has been developed. These ionene‐polyamides are all constitutional isomers varying in the regiochemistry of the amide linkages (para, meta) and xylyl linkages (ortho, meta, para) along the polymer backbone. The physical properties as well as the gas separation behaviors of the corresponding membranes have been extensively studied. These ionene‐polyamide membranes show excellent thermal and mechanical stabilities, together with self‐healing and shape memory characteristics. Most importantly, [TC‐API(p)‐Xy][Tf₂N] and [IC‐API(m)‐Xy][Tf₂N] membranes (TC, terephthaloyl chloride; API, 1‐(3‐aminopropyl)imidazole; Xy, xylyl; Tf₂N, bis(trifluoromethylsulfonyl) imide; IC, isophthaloyl chloride), where the amide and xylyl linkages are attached at para and meta positions, exhibit superior selectivity for CO₂/CH₄and CO₂/N₂gas pairs. We also demonstrate the transport properties and diverse applicability of our newly developed ionene‐polyamides, particularly [TC‐API(p)‐Xy][Tf₂N], for various industrial applications. © 2019 Society of Chemical Industry