Anion-conductive membranes based on 2-mesityl-benzimidazolium functionalised poly(2,6-dimethyl-1,4-phenylene oxide) and their use in alkaline water electrolysis

Angela Marinkas, Izabela Struźyńska-Piron, Yona Lee, Ahyoun Lim, Hyun S. Park, Jong Hyun Jang, Hyoung Juhn Kim, Ji Hyun Kim, Artjom Maljusch, Oliver Conradi, Dirk Henkensmeier

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11 Citations (Scopus)

Abstract

For development of anion exchange membrane (AEM) water electrolysis systems, a series of polymers was synthesised by reacting 2-mesityl-benzimidazole (BIM) and brominated poly-(2,6-dimethyl-1,4-phenylene oxide) (Br-PPO) in a Menshutkin reaction, and permethylating the attached BIM groups. The degree of bromination of Br-PPO can be easily monitored by IR spectroscopy: A correlation with the shift of the band around 1190 cm−1 was found. The IEC values of the prepared materials ranged between 1.6 and 2.9 mmol OH g−1. Only materials with an IEC value of 1.9 (PPO24-BIM) reproducibly formed self-supporting membranes. This may be related to the degree of crystallinity, which decreased from 14 to 3% when the IEC increased from 1.6 to 3 mmol OH g−1. Materials with IEC values of 1.6 and 2.2 can form self-supporting membranes, but not reproducibly. PPO24-BIM showed a conductivity of 8 mS cm-1 at room temperature, a thermal stability well above 200 °C, and mechanical properties similar to those of commercial FAA3-30 membranes. During water electrolysis, a current density of 300 mA cm-2 at 1.8 V was obtained. At 80 °C in 1 M KOH, degradation of BIM and the PPO backbone were observed by IR spectroscopy and monitoring conductivity and weight loss.

Original languageEnglish
Pages (from-to)242-251
Number of pages10
JournalPolymer
Volume145
DOIs
Publication statusPublished - 2018 Jun 6

Keywords

  • 2-Mesityl-benzimidazole
  • Alkaline electrolysis
  • Alkaline stability
  • Anion exchange membrane
  • Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics

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    Marinkas, A., Struźyńska-Piron, I., Lee, Y., Lim, A., Park, H. S., Jang, J. H., Kim, H. J., Kim, J. H., Maljusch, A., Conradi, O., & Henkensmeier, D. (2018). Anion-conductive membranes based on 2-mesityl-benzimidazolium functionalised poly(2,6-dimethyl-1,4-phenylene oxide) and their use in alkaline water electrolysis. Polymer, 145, 242-251. https://doi.org/10.1016/j.polymer.2018.05.008