Adamantammonium as a novel functional group for anion exchange membranes with excellent comprehensive performances

Publication date: 10 March 2017
Source:Polymer, Volume 112
Author(s): Jinlei Wang, Ying Chen, Qi Wei, Shanzhong Yang, Huagao Fang, Haibing Wei, Yunsheng Ding
In the pursuit of alkali stable cation as functional group for anion exchange membranes (AEMs), a novel adamantammonium (AdA) cation, which replacing methyl group of conventional trimethylammonium by an adamantyl group, was synthesized and investigated. ¹H NMR spectroscopy was employed to quantify the extent of decomposition and the results showed that > 99% adamantammonium remaining after 7 days immersion in 2 M NaOH (in D2O) at 80 °C. The AdA functionalized benzyl type poly(2,6-dimethyl phenylene oxide) polyelectrolytes, PPO-AdAs, were further prepared and characterized the AEM properties. Not only the chemical durability of these new PPO-AdA membranes, interestingly, but the conductivity and dimensional stability (water uptake and in-plane swelling) are superior to the benzylmethylammonium-benchmark PPO-based AEM (PPO-TMA). With the similar IEC values, the water uptake of PPO-AdA-41 sample is much lower than PPO-TMA-28, however, the conductivity of the former (15.7 mS cm^-1, chloride conductivity at 50 °C) is higher than the latter (13.3 mS cm^-1). Overall, the results of this study offer a base-stable cation, adamantammonium, and the corresponding adamantammonium-based AEMs for fuel cell applications with the advantages of chemical stability, enhanced conductivity and excellent dimensional stability as well as facial functionalization technique.

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