Anion Transport in a Chemically Stable, Sterically Bulky 伪-C Modified Imidazolium Functionalized Anion Exchange Membrane

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• 作者：Ye Liu ; Junhua Wang ; Yuan Yang ; Thomas M. Brenner ; S枚enke Seifert ; Yushan Yan ; Matthew W. Liberatore ; Andrew M. Herring
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：July 17, 2014
• 年：2014
• 卷：118
• 期：28
• 页码：15136-15145
• 全文大小：468K
• ISSN：1932-7455

文摘

The morphology and anion transport of an 伪-C modified imidazolium functionalized anion exchange membrane, 1,4,5-trimethyl-2-(2,4,6-trimethoxyphenyl)imidazolium functionalized polyphenylene oxide (with ion exchange capacity {IEC} = 1.53 or 1.82 mequiv/g), were studied in detail. The novel cation is less susceptible to OH^{鈥?/sup> attack (0% degradation) compared to unsubstituted imidazolium functionalized polyphenylene oxide (25% degradation) after 24 h at 80 掳C in 1 M KOH. The two different IEC materials (with the same protected cation) show interesting differences in membrane performance. From AFM and SAXS under humid conditions, the domain sizes of the membrane change, which impact the transport properties. The lower IEC sample showed a smaller tortuosity and, thus, needs a longer diffusion time for the water molecules to be fully hindered inside the hydrophobic clusters, which is confirmed by water self-diffusion measurements from pulsed field gradient NMR. From conductivity and diffusion measurements, the higher IEC sample exhibited Vogel鈥揟ammann鈥揊ulcher behavior, thus indicating that the polymer chain鈥檚 movement dominates the transport. However, the lower IEC sample exhibited the linear Arrhenius behavior signifying water-mediated transport. The maximum Cl鈥?/sup> conductivity observed was 23 mS/cm at 95% RH and 90 掳C.}