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Rational molecular design of anion exchange membranes functionalized with alicyclic quaternary ammonium cations

Pham, Thanh Huong LU ; Allushi, Andrit LU ; Olsson, Joel LU and Jannasch, Patric LU orcid (2020) In Polymer Chemistry 11(43). p.6953-6963
Abstract
High alkaline stability is critical for polymeric anion exchange membranes (AEMs) and ionomers for use in alkaline electrochemical energy conversion and storage devices such as fuel cells, electrolyzer cells and advanced batteries. Here, we have prepared and studied ether-free polyfluorenes tethered with N,N-dimethylpiperidinium (DMP) and 6-azonia-spiro[5.5]undecane (ASU) cations, respectively, attached thorough heteroatom-free alkyl spacers. By employing alkyl-alkyl Suzuki cross-coupling, these alicyclic quaternary ammonium cations are attached at the 4-position to impede ionic loss. Thus, all the β-hydrogens sensitive to elimination reactions are placed in strain-free rings able to fully relax by the spacer flexibility.... (More)
High alkaline stability is critical for polymeric anion exchange membranes (AEMs) and ionomers for use in alkaline electrochemical energy conversion and storage devices such as fuel cells, electrolyzer cells and advanced batteries. Here, we have prepared and studied ether-free polyfluorenes tethered with N,N-dimethylpiperidinium (DMP) and 6-azonia-spiro[5.5]undecane (ASU) cations, respectively, attached thorough heteroatom-free alkyl spacers. By employing alkyl-alkyl Suzuki cross-coupling, these alicyclic quaternary ammonium cations are attached at the 4-position to impede ionic loss. Thus, all the β-hydrogens sensitive to elimination reactions are placed in strain-free rings able to fully relax by the spacer flexibility. Consequently, the AEM carrying DMP cations shows a very high alkaline and thermal stability, retaining more than 91% of the cations after 2,400 h immersion in 2 M NaOH at 90 °C. Compared with corresponding AEMs functionalized with N-alkyl-N-methylpiperidinium (AMP) cations (conventionally tethered via the 1(N)-position), the ionic loss by β-elimination is successfully reduced by up to 92%. AEMs functionalized with DMP also reach a high hydroxide conductivity of 124 mS cm-1 at 80 °C. Consequently, tethering piperidine-based cations via the 4-position instead of the 1(N)-position results in AEMs with substantially improved thermal and alkaline stability, combined with high hydroxide conductivity. (Less)
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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Polymer Chemistry
volume
11
issue
43
pages
11 pages
publisher
Royal Society of Chemistry
external identifiers
  • scopus:85096363104
ISSN
1759-9962
DOI
10.1039/D0PY01291B
language
English
LU publication?
yes
additional info
First published 19 Oct 2020
id
9077c775-110b-4efc-bd63-6162ca12eeeb
date added to LUP
2020-06-05 22:39:25
date last changed
2022-04-18 22:38:27
@article{9077c775-110b-4efc-bd63-6162ca12eeeb,
  abstract     = {{High alkaline stability is critical for polymeric anion exchange membranes (AEMs) and ionomers for use in alkaline electrochemical energy conversion and storage devices such as fuel cells, electrolyzer cells and advanced batteries. Here, we have prepared and studied ether-free polyfluorenes tethered with <i>N</i>,<i>N</i>-dimethylpiperidinium (DMP) and 6-azonia-spiro[5.5]undecane (ASU) cations, respectively, attached thorough heteroatom-free alkyl spacers. By employing alkyl-alkyl Suzuki cross-coupling, these alicyclic quaternary ammonium cations are attached at the 4-position to impede ionic loss. Thus, all the β-hydrogens sensitive to elimination reactions are placed in strain-free rings able to fully relax by the spacer flexibility. Consequently, the AEM carrying DMP cations shows a very high alkaline and thermal stability, retaining more than 91% of the cations after 2,400 h immersion in 2 M NaOH at 90 °C. Compared with corresponding AEMs functionalized with <i>N</i>-alkyl-<i>N</i>-methylpiperidinium (AMP) cations (conventionally tethered via the 1(<i>N</i>)-position), the ionic loss by β-elimination is successfully reduced by up to 92%. AEMs functionalized with DMP also reach a high hydroxide conductivity of 124 mS cm<sup>-1</sup> at 80 °C. Consequently, tethering piperidine-based cations via the 4-position instead of the 1(<i>N</i>)-position results in AEMs with substantially improved thermal and alkaline stability, combined with high hydroxide conductivity.}},
  author       = {{Pham, Thanh Huong and Allushi, Andrit and Olsson, Joel and Jannasch, Patric}},
  issn         = {{1759-9962}},
  language     = {{eng}},
  number       = {{43}},
  pages        = {{6953--6963}},
  publisher    = {{Royal Society of Chemistry}},
  series       = {{Polymer Chemistry}},
  title        = {{Rational molecular design of anion exchange membranes functionalized with alicyclic quaternary ammonium cations}},
  url          = {{http://dx.doi.org/10.1039/D0PY01291B}},
  doi          = {{10.1039/D0PY01291B}},
  volume       = {{11}},
  year         = {{2020}},
}