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Abstract Polyimides (PI) synthesized from 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with various diamines have been frequently studied as gas separation membranes. The use of 6FDA in polyimides creates a bent structure than can increase fractional free volume (FFV) and gas permeability. Here, we demonstrate that 6FDA is also a useful building block for PI‐ionene materials, which contain cations directly within the polymer backbone. These new 6FDA‐containing PI‐ionenes were combined with several different imidazolium ionic liquids (ILs) to form thin membranes. The thermal properties of all the derivatives were investigated to determine the relationship between regiochemistry and degradation as well as the intermolecular forces that are present within these structures. The gas separation properties of these 6FDA‐containing PI‐ionene + IL materials were investigated, showing modest CO2permeabilities similar to other polyimide‐ionenes and CO2/CH4and CO2/N2permselectivities that were relatively higher than other polyimide‐ionenes.
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Understanding the effects of backbone chemistry and anion type on the structure and thermal behaviors of imidazolium polyimide‐ionenes
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
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- PAR ID:
- 10374847
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Polymer International
- Volume:
- 68
- Issue:
- 9
- ISSN:
- 0959-8103
- Format(s):
- Medium: X Size: p. 1547-1556
- Size(s):
- p. 1547-1556
- Sponsoring Org:
- National Science Foundation
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