Synthesis and Characterization of 4-Vinylimidazolium/Styrene-Cografted Anion-Conducting Electrolyte Membranes

Takashi Hamada*, Kimio Yoshimura, Kota Takeuchi, Shun Watanabe, Yue Zhao, Akihiro Hiroki, Tokio Hagiwara, Hideyuki Shishitani, Susumu Yamaguchi, Hirohisa Tanaka, Aurel Radulescu, Kenji Ohwada, Yasunari Maekawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The β-hydrogen-free imidazole monomer, 2-methyl-N-methyl-4(5)-vinylimidazole (2M4VIm), is synthesized to prepare anion exchange membranes (AEMs). The radiation-induced graft polymerization of 2M4VIm and styrene is performed in poly(ethylene-co-tetrafluoroethylene), followed by N-alkylation and ion exchange reactions to prepare 4-vinylimidazolium-containing AEM (2M4VIm/St-AEM). AEMs that have a 6/4 2M4VIm/St molar ratio and 1.7 mmol g−1 ion exchange capacity (IEC) result in 75 mS cm−1 conductivity and 60% water uptake at room temperature in water, demonstrating enhanced values compared to previously reported 2-methyl-N-vinylimidazolium-containing AEMs (2MNVIm/St-AEM) that have a similar comonomer ratio and IEC. The small-angle neutron scattering measurements of dry and swollen 2M4VIm/St-AEM reveal hydrophilic/hydrophobic two-phase separation, as observed for 2MNVIm/St-AEM with a similar Im/St composition. 2M4VIm/St-AEMs exhibit higher alkaline stability in 1 m KOH at 80 °C at an early stage owing to the suppression of imidazolium β-elimination but lower long-term stability than that of 2MNVIm/St-AEM due to the ring-opening reaction of the imidazolium group due to its outward orientation from the graft main chain.

Original languageEnglish
Article number2100028
JournalMacromolecular Chemistry and Physics
Volume222
Issue number11
DOIs
Publication statusPublished - 2021 Jun
Externally publishedYes

Keywords

  • alkaline durability
  • anion-conducting electrolyte membranes
  • imidazole
  • poly(ethylene-co-tetrafluoroethylene)
  • radiation-induced graft polymerization

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

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