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Poly(N,N-diallylazacycloalkane)s for anion-exchange membranes functionalized with N-spirocyclic quaternary ammonium cations

Olsson, Joel S. LU ; Pham, Thanh Huong LU and Jannasch, Patric LU (2017) In Macromolecules 50(7). p.2784-2793
Abstract
The alkaline stability of organic cations tethered to anion-exchange membranes (AEMs) is essential for the long-term performance of alkaline membrane fuel cells and electrolyzers. Here, we have prepared and studied the thermal and alkaline stability of a series of polyelectrolytes functionalized with N-spirocyclic quaternary ammonium (QA) cations. N,N-diallyl azacycloalkane quaternary salts were readily synthesized by diallylation of pyrrolidine, piperidine, azepane, and morpholine, respectively. These monomers were employed in radical-initiated cyclo-polymerizations to obtain the target poly(N,N-diallyl azacycloalkane)s. 1H NMR spectroscopy revealed that the stability of the polyelectrolytes... (More)
The alkaline stability of organic cations tethered to anion-exchange membranes (AEMs) is essential for the long-term performance of alkaline membrane fuel cells and electrolyzers. Here, we have prepared and studied the thermal and alkaline stability of a series of polyelectrolytes functionalized with N-spirocyclic quaternary ammonium (QA) cations. N,N-diallyl azacycloalkane quaternary salts were readily synthesized by diallylation of pyrrolidine, piperidine, azepane, and morpholine, respectively. These monomers were employed in radical-initiated cyclo-polymerizations to obtain the target poly(N,N-diallyl azacycloalkane)s. 1H NMR spectroscopy revealed that the stability of the polyelectrolytes in 2 M KOD/D2O solutions critically depended on the ring size and the absence of additional heteroatoms in the ring. Thus, poly(N,N-diallyl piperidinium) showed the highest alkaline stability, with only minor signs of degradation at 120 °C after 14 days, while the polyelectrolytes based on the morpholine and azepane rings clearly degraded via both Hofmann elimination and ring-opening substitution already at 90 °C. Crosslinked water non-soluble AEMs were prepared by copolymerizing N,N-diallyl piperidinium chloride with methylbenzyldiallyl ammonium groups tethered to poly(phenylene oxide). These transparent and mechanically robust AEMs reached high OH conductivities, above 0.1 S cm-1 at 80 °C. The present work demonstrate the high alkaline stability of suitably configured N-spirocyclic QA cations, which will open up new prospects for readily accessible high performance polyelectrolytes and membranes. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Macromolecules
volume
50
issue
7
pages
2784 - 2793
publisher
The American Chemical Society
external identifiers
  • scopus:85017653598
  • wos:000399263900019
ISSN
0024-9297
DOI
10.1021/acs.macromol.7b00168
language
English
LU publication?
yes
id
2a6a9e44-0cf7-42df-8217-ebb6f5d4b0bc
date added to LUP
2017-03-17 23:47:34
date last changed
2018-05-20 04:32:35
@article{2a6a9e44-0cf7-42df-8217-ebb6f5d4b0bc,
  abstract     = {The alkaline stability of organic cations tethered to anion-exchange membranes (AEMs) is essential for the long-term performance of alkaline membrane fuel cells and electrolyzers. Here, we have prepared and studied the thermal and alkaline stability of a series of polyelectrolytes functionalized with <i>N</i>-spirocyclic quaternary ammonium (QA) cations. <i>N</i>,<i>N</i>-diallyl azacycloalkane quaternary salts were readily synthesized by diallylation of pyrrolidine, piperidine, azepane, and morpholine, respectively. These monomers were employed in radical-initiated cyclo-polymerizations to obtain the target poly(<i>N</i>,<i>N</i>-diallyl azacycloalkane)s. <sup>1</sup>H NMR spectroscopy revealed that the stability of the polyelectrolytes in 2 M KOD/D<sub>2</sub>O solutions critically depended on the ring size and the absence of additional heteroatoms in the ring. Thus, poly(<i>N</i>,<i>N</i>-diallyl piperidinium) showed the highest alkaline stability, with only minor signs of degradation at 120 °C after 14 days, while the polyelectrolytes based on the morpholine and azepane rings clearly degraded via both Hofmann elimination and ring-opening substitution already at 90 °C. Crosslinked water non-soluble AEMs were prepared by copolymerizing <i>N</i>,<i>N</i>-diallyl piperidinium chloride with methylbenzyldiallyl ammonium groups tethered to poly(phenylene oxide). These transparent and mechanically robust AEMs reached high OH<sup>–</sup> conductivities, above 0.1 S cm<sup>-1</sup> at 80 °C. The present work demonstrate the high alkaline stability of suitably configured <i>N</i>-spirocyclic QA cations, which will open up new prospects for readily accessible high performance polyelectrolytes and membranes. },
  author       = {Olsson, Joel S. and Pham, Thanh Huong and Jannasch, Patric},
  issn         = {0024-9297},
  language     = {eng},
  number       = {7},
  pages        = {2784--2793},
  publisher    = {The American Chemical Society},
  series       = {Macromolecules},
  title        = {Poly(<i>N</i>,<i>N</i>-diallylazacycloalkane)s for anion-exchange membranes functionalized with <i>N</i>-spirocyclic quaternary ammonium cations},
  url          = {http://dx.doi.org/10.1021/acs.macromol.7b00168},
  volume       = {50},
  year         = {2017},
}