Ether-free polyfluorenes tethered with quinuclidinium cations as hydroxide exchange membranes
Allushi, Andrit LU ; Pham, Thanh Huong LU ; Olsson, Joel LU and Jannasch, Patric LU
(2019)
In Journal of Materials Chemistry A
7(47).
p.27164-27174
- Abstract
- We report on aryl ether-free 2,7-diphenylfluorene-based copolymers tethered with quinuclidinium (Qui) cations via hexyl spacers, prepared through superacid catalyzed Friedel Crafts polycondensation and quaternization reactions. The 2,7-diphenylfluorene monomers were prepared by Suzuki coupling and employed to increase polymer backbone stiffness. Corresponding copolymers and anion-exchange membranes (AEMs) tethered with piperidinium (Pip) and trimethylalkyl ammonium (TMA) cations were prepared as reference materials. At a given water content, the AEM functionalized with Qui cations was the most efficient hydroxide conductor and reached 100 mS cm-1 at 80 °C at an ion exchange capacity of 2.0 mequiv g-1. Moreover, this... (More)
- We report on aryl ether-free 2,7-diphenylfluorene-based copolymers tethered with quinuclidinium (Qui) cations via hexyl spacers, prepared through superacid catalyzed Friedel Crafts polycondensation and quaternization reactions. The 2,7-diphenylfluorene monomers were prepared by Suzuki coupling and employed to increase polymer backbone stiffness. Corresponding copolymers and anion-exchange membranes (AEMs) tethered with piperidinium (Pip) and trimethylalkyl ammonium (TMA) cations were prepared as reference materials. At a given water content, the AEM functionalized with Qui cations was the most efficient hydroxide conductor and reached 100 mS cm-1 at 80 °C at an ion exchange capacity of 2.0 mequiv g-1. Moreover, this membrane showed the highest thermal and alkaline stability in the series. 1H NMR analysis of AEMs stored in 2 M aq. NaOH at 90 °C over 672 h revealed the complete absence of ring-opening β-elimination in the bicyclic cage-like Qui structure, and only ~1% β-elimination in the hexyl spacer. In contrast, the Pip cations were found to degrade via β-elimination in both the monocyclic ring structure and the hexyl spacer. Results on the Pip-modified AEM implied that a β-hydrogen in the linear alkyl spacer chain was approximately 4 times more vulnerable to elimination than a β-hydrogen in the 6-membered ring. In addition, all the cations degraded via substitution reactions to some degree, and the total loss of Qui, Pip and TMA cations over the period was estimated to 4, 12 and 9%, respectively. The overall findings demonstrate that the combination of aryl-ether free backbone polymers and Qui cations results in durable and high-performance AEMs suitable for use in alkaline electrochemical energy conversion and storage devices. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/44971746-b87d-43a0-ba2c-83cea72cf31c
- author
- Allushi, Andrit
LU
; Pham, Thanh Huong
LU
; Olsson, Joel
LU
and Jannasch, Patric
LU
- organization
- publishing date
- 2019
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of Materials Chemistry A
- volume
- 7
- issue
- 47
- pages
- 11 pages
- publisher
- Royal Society of Chemistry
- external identifiers
-
- scopus:85076052653
- ISSN
- 2050-7488
- DOI
- 10.1039/C9TA09213G
- language
- English
- LU publication?
- yes
- additional info
- The article was received on 21 Aug 2019, accepted on 11 Nov 2019 and first published on 11 Nov 2019.
- id
- 44971746-b87d-43a0-ba2c-83cea72cf31c
- date added to LUP
- 2019-11-06 08:57:34
- date last changed
- 2022-04-18 18:35:25
@article{44971746-b87d-43a0-ba2c-83cea72cf31c,
abstract = {{We report on aryl ether-free 2,7-diphenylfluorene-based copolymers tethered with quinuclidinium (Qui) cations via hexyl spacers, prepared through superacid catalyzed Friedel Crafts polycondensation and quaternization reactions. The 2,7-diphenylfluorene monomers were prepared by Suzuki coupling and employed to increase polymer backbone stiffness. Corresponding copolymers and anion-exchange membranes (AEMs) tethered with piperidinium (Pip) and trimethylalkyl ammonium (TMA) cations were prepared as reference materials. At a given water content, the AEM functionalized with Qui cations was the most efficient hydroxide conductor and reached 100 mS cm<sup>-1</sup> at 80 °C at an ion exchange capacity of 2.0 mequiv g<sup>-1</sup>. Moreover, this membrane showed the highest thermal and alkaline stability in the series. <sup>1</sup>H NMR analysis of AEMs stored in 2 M aq. NaOH at 90 °C over 672 h revealed the complete absence of ring-opening β-elimination in the bicyclic cage-like Qui structure, and only ~1% β-elimination in the hexyl spacer. In contrast, the Pip cations were found to degrade via β-elimination in both the monocyclic ring structure and the hexyl spacer. Results on the Pip-modified AEM implied that a β-hydrogen in the linear alkyl spacer chain was approximately 4 times more vulnerable to elimination than a β-hydrogen in the 6-membered ring. In addition, all the cations degraded via substitution reactions to some degree, and the total loss of Qui, Pip and TMA cations over the period was estimated to 4, 12 and 9%, respectively. The overall findings demonstrate that the combination of aryl-ether free backbone polymers and Qui cations results in durable and high-performance AEMs suitable for use in alkaline electrochemical energy conversion and storage devices.}},
author = {{Allushi, Andrit and Pham, Thanh Huong and Olsson, Joel and Jannasch, Patric}},
issn = {{2050-7488}},
language = {{eng}},
number = {{47}},
pages = {{27164--27174}},
publisher = {{Royal Society of Chemistry}},
series = {{Journal of Materials Chemistry A}},
title = {{Ether-free polyfluorenes tethered with quinuclidinium cations as hydroxide exchange membranes}},
url = {{http://dx.doi.org/10.1039/C9TA09213G}},
doi = {{10.1039/C9TA09213G}},
volume = {{7}},
year = {{2019}},
}