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Highly alkali-stable zwitterionic poly(arylene quinuclidinium) anion exchange membranes

Mansouri Bakvand, Pegah LU and Jannasch, Patric LU orcid (2025) In Journal of Membrane Science 717.
Abstract
Alkaline electrochemical energy conversion devices generally require anion exchange membranes (AEMs) which combine limited water uptake and swelling with high hydroxide conductivity and high resistance against attack by the ubiquitous hydroxide ions. In this context, zwitterionic AEMs may offer distinct possibilities to tune AEM properties in relation to purely cationic AEMs. Here, we report on the preparation and characterization of a series of poly(p-terphenyl quinuclidinium) AEMs functionalized with both zwitterionic and cationic groups. In order to control the ionic contents, a zwitterionic N-sulfobutylquinuclidinium-3-one monomer was synthesized and employed together with 3-quinuclidone in superacid-mediated... (More)
Alkaline electrochemical energy conversion devices generally require anion exchange membranes (AEMs) which combine limited water uptake and swelling with high hydroxide conductivity and high resistance against attack by the ubiquitous hydroxide ions. In this context, zwitterionic AEMs may offer distinct possibilities to tune AEM properties in relation to purely cationic AEMs. Here, we report on the preparation and characterization of a series of poly(p-terphenyl quinuclidinium) AEMs functionalized with both zwitterionic and cationic groups. In order to control the ionic contents, a zwitterionic N-sulfobutylquinuclidinium-3-one monomer was synthesized and employed together with 3-quinuclidone in superacid-mediated polyhydroxyalkylations with p-terphenyl, followed by complete quaternization of the resulting copolymers. With hydroxide exchange capacities between 2.08 and 2.45 mequiv g-1, the AEMs reached high hydroxide conductivities, 100-139 mS cm-1, with 94 to 143% water uptakes at 80 ºC. In addition, the AEMs showed outstanding alkaline stability with no signs of degradation by NMR analysis after 720 h storage in 5 M aq. NaOH at 90 ºC. After storage in 10 M aq. NaOH at 90 °C, the zwitterionic AEMs showed a mere 4% ionic loss through the substitution of the sulfoalkyl chain. In comparison, a corresponding zwitterionic AEM based on poly(p-terphenyl piperidinium) suffered a severe ionic loss, i.e., 63% by Hofmann β-elimination and 11% through methyl substitution, under the same conditions. The study showed that polymers functionalized with both zwitterionic and anionic groups based on quinuclidine are attractive AEM materials, combining restricted water uptake and swelling with high hydroxide conductivity. Moreover, these AEMs possess an outstanding alkaline stability because the cage-like structure of the quinuclidinium cation efficiently hinders degradation by Hofmann β-elimination. (Less)
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author
and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Membrane Science
volume
717
article number
123656
pages
11 pages
publisher
Elsevier
external identifiers
  • scopus:85213286153
ISSN
0376-7388
DOI
10.1016/j.memsci.2024.123656
language
English
LU publication?
yes
id
1b3963cb-5895-4de1-b02c-a2894de790c3
date added to LUP
2024-08-27 09:41:46
date last changed
2025-04-04 14:53:32
@article{1b3963cb-5895-4de1-b02c-a2894de790c3,
  abstract     = {{Alkaline electrochemical energy conversion devices generally require anion exchange membranes (AEMs) which combine limited water uptake and swelling with high hydroxide conductivity and high resistance against attack by the ubiquitous hydroxide ions. In this context, zwitterionic AEMs may offer distinct possibilities to tune AEM properties in relation to purely cationic AEMs. Here, we report on the preparation and characterization of a series of poly(<i>p</i>-terphenyl quinuclidinium) AEMs functionalized with both zwitterionic and cationic groups. In order to control the ionic contents, a zwitterionic <i>N</i>-sulfobutylquinuclidinium-3-one monomer was synthesized and employed together with 3-quinuclidone in superacid-mediated polyhydroxyalkylations with <i>p</i>-terphenyl, followed by complete quaternization of the resulting copolymers. With hydroxide exchange capacities between 2.08 and 2.45 mequiv g<sup>-1</sup>, the AEMs reached high hydroxide conductivities, 100-139 mS cm<sup>-1</sup>, with 94 to 143% water uptakes at 80 ºC. In addition, the AEMs showed outstanding alkaline stability with no signs of degradation by NMR analysis after 720 h storage in 5 M aq. NaOH at 90 ºC. After storage in 10 M aq. NaOH at 90 °C, the zwitterionic AEMs showed a mere 4% ionic loss through the substitution of the sulfoalkyl chain. In comparison, a corresponding zwitterionic AEM based on poly(<i>p</i>-terphenyl piperidinium) suffered a severe ionic loss, i.e., 63% by Hofmann β-elimination and 11% through methyl substitution, under the same conditions. The study showed that polymers functionalized with both zwitterionic and anionic groups based on quinuclidine are attractive AEM materials, combining restricted water uptake and swelling with high hydroxide conductivity. Moreover, these AEMs possess an outstanding alkaline stability because the cage-like structure of the quinuclidinium cation efficiently hinders degradation by Hofmann β-elimination.}},
  author       = {{Mansouri Bakvand, Pegah and Jannasch, Patric}},
  issn         = {{0376-7388}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Membrane Science}},
  title        = {{Highly alkali-stable zwitterionic poly(arylene quinuclidinium) anion exchange membranes}},
  url          = {{http://dx.doi.org/10.1016/j.memsci.2024.123656}},
  doi          = {{10.1016/j.memsci.2024.123656}},
  volume       = {{717}},
  year         = {{2025}},
}