Ion transport analysis of anion-exchange membranes in various hydration states: Combining experiments with molecular dynamics simulation

Nara, Yuri; Kasahara, Kento; Yagi, Kiyoshi; Kim, Kang; Matubayasi, Nobuyuki; Kawakami, Hiroyoshi; Tanaka, Manabu

doi:https://doi.org/10.1021/acsapm.5c03130

Ion transport analysis of anion-exchange membranes in various hydration states: Combining experiments with molecular dynamics simulation

Nara, Yuri; Kasahara, Kento; Yagi, Kiyoshi et al.

ACS Applied Polymer Materials, 2025, 7(20), 13971-13981

Number of Access:23（2025-12-05 01:58 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/102982

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Title	Ion transport analysis of anion-exchange membranes in various hydration states: Combining experiments with molecular dynamics simulation
Creator	CreatorName Nara, Yuri
	NRID 1000010824469 1000010824469 ORCID 0000-0001-7138-250X 0000-0001-7138-250X researchmap permalink kasakento kasakento Scopus Author ID 56245700800 56245700800 CreatorName Kasahara, Kento
	NRID 1000030401128 1000030401128 CreatorName Yagi, Kiyoshi
	NRID 1000020442527 1000020442527 ORCID 0000-0002-7047-3183 0000-0002-7047-3183 researchmap permalink kangkim kangkim CreatorName Kim, Kang
	NRID 1000020281107 1000020281107 ORCID 0000-0001-7176-441X 0000-0001-7176-441X researchmap permalink nbyk_MTBYS nbyk_MTBYS Scopus Author ID 7003410578 7003410578 CreatorName Matubayasi, Nobuyuki
	NRID 1000010221897 1000010221897 CreatorName Kawakami, Hiroyoshi
	NRID 1000000531831 1000000531831 CreatorName Tanaka, Manabu
Subject	all-atom molecular dynamics simulation
	anion conductivity
	anion exchange membrane
	hydration
	polyfluorene
Description	This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Polymer Materials, © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsapm.5c03130
Description	Nara Y., Kasahara K., Yagi K., et al. Ion Transport Analysis of Anion-Exchange Membranes in Various Hydration States: Combining Experiments with Molecular Dynamics Simulation. ACS Applied Polymer Materials 7, 13971 (2025); https://doi.org/10.1021/acsapm.5c03130.
Abstract	Anion exchange membrane (AEM)-based systems are a viable approach for fuel cells and water electrolyzers, since they operate under alkaline conditions and allow the use of cost-effective, abundant catalysts such as iron and nickel. The current challenges of AEM are the low anion conductivity and insufficient chemical (alkaline) stability. Especially, the anion conductivity drops in low hydration states at reduced humidities. To overcome these issues, it is crucial to understand how the polymer morphology changes with hydration states and why low humidity conditions lead to a decrease in anion conductivity. In the present study, all-atom molecular dynamics (MD) simulations have been carried out to elucidate the hydration structure of trimethylammonium-substituted polyfluorene (TMA-PF), previously reported by the authors [Nara et al., Polym. Adv. Technol. 2022, 33, 2863–2871], with various water contents (number of water molecules per anion exchange group: λ = 0–10). The simulation results indicate that the anion exchange groups were aggregated with water molecules as the proportion of the water contents increased, which led to well-connected hydrophilic phases constructing anion conduction pathways. However, such hydrophilic channels remained connected even at low hydration states. Further analyses on local structures around the anion exchange groups revealed that most anions were trapped by multiple anion exchange groups under low-humidity conditions. The strong electrostatic interactions between the anions and the anion exchange groups suppress the anion mobility and lead to low anion conductivity under low-humidity conditions. The present findings obtained from combined experimental and computational works are useful for promoting practical applications of AEM-based systems.
Publisher	American Chemical Society
Source Title	ACS Applied Polymer Materials
Volume (Issue)	7(20)
Page	13971-13981
Date of Issued	2025-10-09
Language	English
Handle URL	https://hdl.handle.net/11094/102982
eISSN	26376105
Relation.isVersionOf	DOI (Publisher Version) https://doi.org/10.1021/acsapm.5c03130
Access Rights	embargoed access
CopyRight	The full-text file will be made open to the public on 9 October 2026 in accordance with the publisher's policy.
oaire:version	Accepted Manuscript
Category	学術雑誌論文 Journal Article

Resource Type	journal article
Local Type	Journal Article
DCMI Type	Text
DCTERMS.bibliographicCitation	ACS Applied Polymer Materials. 2025, 7(20), p. 13971-13981
DC.title	Ion transport analysis of anion-exchange membranes in various hydration states: Combining experiments with molecular dynamics simulation
DC.creator	Nara, Yuri
	Kasahara, Kento
	Yagi, Kiyoshi
	Kim, Kang
	Matubayasi, Nobuyuki
	Kawakami, Hiroyoshi
	Tanaka, Manabu
DC.publisher	American Chemical Society
DC.language' scheme='DCTERMS.RFC1766	English
DC.type' scheme='DCTERMS.DCMIType	Text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2025-10-09
DC.identifier	https://doi.org/10.1021/acsapm.5c03130
DC.subject	all-atom molecular dynamics simulation
	anion conductivity
	anion exchange membrane
	hydration
	polyfluorene
DC.description	This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Polymer Materials, © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsapm.5c03130
DC.description	Nara Y., Kasahara K., Yagi K., et al. Ion Transport Analysis of Anion-Exchange Membranes in Various Hydration States: Combining Experiments with Molecular Dynamics Simulation. ACS Applied Polymer Materials 7, 13971 (2025); https://doi.org/10.1021/acsapm.5c03130.
DCTERMS.abstract	Anion exchange membrane (AEM)-based systems are a viable approach for fuel cells and water electrolyzers, since they operate under alkaline conditions and allow the use of cost-effective, abundant catalysts such as iron and nickel. The current challenges of AEM are the low anion conductivity and insufficient chemical (alkaline) stability. Especially, the anion conductivity drops in low hydration states at reduced humidities. To overcome these issues, it is crucial to understand how the polymer morphology changes with hydration states and why low humidity conditions lead to a decrease in anion conductivity. In the present study, all-atom molecular dynamics (MD) simulations have been carried out to elucidate the hydration structure of trimethylammonium-substituted polyfluorene (TMA-PF), previously reported by the authors [Nara et al., Polym. Adv. Technol. 2022, 33, 2863–2871], with various water contents (number of water molecules per anion exchange group: λ = 0–10). The simulation results indicate that the anion exchange groups were aggregated with water molecules as the proportion of the water contents increased, which led to well-connected hydrophilic phases constructing anion conduction pathways. However, such hydrophilic channels remained connected even at low hydration states. Further analyses on local structures around the anion exchange groups revealed that most anions were trapped by multiple anion exchange groups under low-humidity conditions. The strong electrostatic interactions between the anions and the anion exchange groups suppress the anion mobility and lead to low anion conductivity under low-humidity conditions. The present findings obtained from combined experimental and computational works are useful for promoting practical applications of AEM-based systems.
DC.rights	The full-text file will be made open to the public on 9 October 2026 in accordance with the publisher's policy.
DC.format	102982
citation_title	Ion transport analysis of anion-exchange membranes in various hydration states: Combining experiments with molecular dynamics simulation
citation_author	Nara, Yuri
	Kasahara, Kento
	Yagi, Kiyoshi
	Kim, Kang
	Matubayasi, Nobuyuki
	Kawakami, Hiroyoshi
	Tanaka, Manabu
citation_publisher	American Chemical Society
citation_language	English
citation_date	2025-10-09
citation_journal_title	ACS Applied Polymer Materials
citation_volume	7
citation_issue	20
citation_firstpage	13971
citation_lastpage	13981
citation_doi	https://doi.org/10.1021/acsapm.5c03130
citation_public_url	https://hdl.handle.net/11094/102982

Ion transport analysis of anion-exchange membranes in various hydration states: Combining experiments with molecular dynamics simulation

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