OH− Conductive Properties and Water Uptake of Anion Exchange Thin Films

• Autor: Wang, Fangfang ; Wang, Dongjin ; Nagao, Yuki
• Materias: Anion exchanging ; Benzene ; electrolytes ; fuel cells ; In situ measurement ; Ionomers ; Membranes ; OH− conductivity ; Proton conduction ; Relative humidity ; Thin films ; Water chemistry ; water uptake
• Es parte de: ChemSusChem, 2021-07, Vol.14 (13), p.2694-2697
• Notas: ObjectType-Article-1
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• Descripción: Several investigations have indicated that proton conduction and hydration properties of acidic ionomers differ from those of membranes. However, relations between the OH− conductivity and water uptake in thin film forms of anion exchange membranes have not been reported yet. For this study, new in situ measurements were established to elucidate the OH− conductivity and water uptake without allowing any influence of CO2 from the air. Poly[(9,9‐bis(6′‐(N,N,N‐trimethylammonium)‐hexyl)‐9H‐fluorene)‐alt‐(1,4‐benzene)], denoted as PFB+, was synthesized as a model ionomer. The highest OH− conductivity of 273 nm‐thick PFB+ film was 5.3×10−2 S cm−1 at 25 °C under 95 % relative humidity (RH), which is comparable to the reported OH− conductivity of PFB+ membrane. Reduced OH− conductivity was found in the thinner film at 95 % RH. The decreased OH− conductivity is explainable by the reduced number of water molecules contained in the thinner film. The OH− conductivity was reduced only slightly under the same water uptake. Anion exchange: Poly[(9,9‐bis(6′‐(N,N,N‐trimethylammonium)‐hexyl)‐9H‐fluorene)‐alt‐(1,4‐benzene)] (PFB+) is used as a model ionomer to investigate the OH− conductivity and water uptake in thin film form. Reduced OH− conductivity is observed in the thinner film at 95 % relative humidity, which can be attributed to the decreased amount of water content. The OH− conductivity is only slightly reduced under the same water uptake.
  
• Editor: Germany: Wiley Subscription Services, Inc
  
• Idioma: Inglés