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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

 

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

 

Here we introduce the synthesis and thermal properties of a series of sophisticated imidazolium ionenes with alternating amide-amide or amide-imide backbone functionality, and investigate the structural effects of mono(imidazolium) and unprecedented tris(imidazolium) ionic liquids (ILs) in these ionenes. The new set of poly(amide-amide) (PAA) and poly(amide-imide) (PAI) ionenes represent the intersection of conventional high-performance polymers with the ionene archetype–presenting polymers with alternating functional and ionic elements precisely sequenced along the backbone. The effects of polymer composition on the thermal properties and morphology were analyzed. Five distinct polymer backbones were synthesized and combined with a stoichiometric equivalent of the IL 1-benzyl-3-methylimidazolium bistriflimide ([Bnmim][Tf2N]), which were studied to probe the self-assembly, structuring, and contributions of intermolecular forces when IL is added. Furthermore, three polyamide (PA) or polyimide (PI) ionenes with simpler xylyl linkages were interfaced with [Bnmim][Tf2N] as well as a novel amide-linked tris(imidazolium) IL, to demonstrate the structural changes imparted by the inclusion of functional, ionic additives dispersed within the ionene matrix. This work highlights the possibilities for utilizing concepts from small molecules which exhibit supramolecular self-assembly to guide creative design and manipulate the structuring of ionenes. 

Here, we report the synthesis and thermophysical properties of seven primarily aromatic, imidazolium-based polyamide ionenes. The effects of varied para-, meta-, and ortho-connectivity, and spacing of ionic and amide functional groups, on structural and thermophysical properties were analyzed. Suitable, robust derivatives were cast into thin films, neat, or with stoichiometric equivalents of the ionic liquid (IL) 1-benzy-3-methylimidazolium bistriflimide ([Bnmim][Tf2N]), and the gas transport properties of these membranes were measured. Pure gas permeabilities and permselectivities for N2, CH4, and CO2 are reported. Consistent para-connectivity in the backbone was shown to yield the highest CO2 permeability and suitability for casting as a very thin, flexible film. Derivatives containing terephthalamide segments exhibited the highest CO2/CH4 and CO2/N2 selectivities, yet CO2 permeability decreased with further deviation from consistent para-linkages.