The impact of alkyl tri‐methyl ammonium side chains on perfluorinated ionic membranes for electrochemical applications

• Published in: Journal of polymer science. Part B, Polymer physics Polymer physics, 2019-06, Vol.57 (11), p.700-712
• Main Authors: Divekar, Ashutosh G., Kuo, Mei‐Chen, Park, Andrew M., Motz, Andrew R., Page‐Belknap, Zachary S., Owczarczyk, Zbyslaw, Long, Hai, Seifert, Soenke, Maupin, Christopher Mark, Yandrasits, Michael A., Yang, Yuan, Pivovar, Bryan S., Herring, Andrew M.
• Format: Article
• Language: English
• Subjects: anion exchange membranes; Anion exchanging; Carbon; electrochemical applications; electrochemistry; fuel cells; Membranes; perfluorinated AEMs; polyelectrolytes; Polymers; polytetrafluoroethylene; Sulfonamides
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.24825

ABSTRACT Three different perfluorinated type polymers as anion exchange membranes for electrochemical applications were studied. They have a sulfonamide linkage to a spacer methylene chain attached to a tri‐methyl ammonium cation, specifically using a three carbon spacer chain (PFAEM_H_C3), and methylated imide polymers with three (PFAEM_CH3_C3) and six carbon spacer chain (PFAEM_CH3_C6). There are significant number of zwitterionic side chains in the PFAEM_H_C3 polymer and very few in the PFAEM_CH3_C3 or the PFAEM_CH3_C6 polymer. They have similar halide conductivity, but the PFAEM_CH3_C6 showed highest OH− conductivity, 122 mS cm−1 at 80 °C and 95% RH. The larger spacer chain polymer, PFAEM_CH3_C6 has a higher water uptake value (λ = 9) compared to PFAEM_CH3_C3(λ = 7) at 60 °C and 95% RH in the Cl− form. Therefore, it has a larger domain spacing of 4.9 nm versus 4.1 nm from small angle X‐ray scattering data. The polymer was characterized by FTIR and DFT was used to fully assign the spectra. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 700–712 Three perfluorinated type polymers are studied with different carbon spacer chains for electrochemical applications. One of them, with a three carbon spacer chain, displays zwitterionic character, while the other two, with three and six carbon spacer chains, are of an anionic type. The polymers are physically and electrochemically characterized. They show decent halide conductivity and one of them has an impressive OH− conductivity of 122 mS cm−1, which makes it a good candidate for electrochemical applications.