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, Jihyun Kim, Artjom Maljusch, Oliver Conradi, Dirk Henkensmeier

Research output: Contribution to journalArticlepeer-review

40 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

Bibliographical note

Funding Information:
Funding from Evonik Creavis and KIST is gratefully acknowledged. The authors also thank Prof. Ronghuan He for helpful discussions, and Dr. Robert Jan Sedelmayer for help with the synthesis.

Publisher Copyright:
© 2018 Elsevier Ltd

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
  • Materials Chemistry

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