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Synthesis and Characterization of 4‐Vinylimidazolium/Styrene‐Cografted Anion‐Conducting Electrolyte Membranes
Author(s) -
Hamada Takashi,
Yoshimura Kimio,
Takeuchi Kota,
Watanabe Shun,
Zhao Yue,
Hiroki Akihiro,
Hagiwara Tokio,
Shishitani Hideyuki,
Yamaguchi Susumu,
Tanaka Hirohisa,
Radulescu Aurel,
Ohwada Kenji,
Maekawa Yasunari
Publication year - 2021
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.202100028
Subject(s) - comonomer , styrene , chemistry , polymer chemistry , ion exchange , monomer , polymerization , membrane , nuclear chemistry , copolymer , ion , organic chemistry , polymer , biochemistry
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.