Infrared Spectroscopic and DFT Vibrational Mode Study of Perfluoro(2-ethoxyethane) Sulfonic Acid (PES), a Model Nafion Side-Chain Molecule

We have used attenuated total reflection infrared (ATR-IR) spectroscopy to study the model compound perfluoro(2-ethoxyethane) sulfonic acid (PES) and the spectral changes induced by humidity variations to improve understanding of the IR spectrum of Nafion. This work was supported by density function...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2008-08, Vol.112 (34), p.10535-10543
Main Authors: Warren, David S, McQuillan, A. James
Format: Article
Language:English
Subjects:
B: Surfactants, Membranes
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Summary:We have used attenuated total reflection infrared (ATR-IR) spectroscopy to study the model compound perfluoro(2-ethoxyethane) sulfonic acid (PES) and the spectral changes induced by humidity variations to improve understanding of the IR spectrum of Nafion. This work was supported by density functional theory (DFT) calculations of the PES molecule and ion complexes to confirm assignments and determine local modes that contributed to specific absorptions in the IR spectrum. The work illustrates the difficulties of interpreting the spectrum of Nafion with several mixed modes being present. However, the loss of degeneracy in the −SO3 − asymmetric stretching mode is clearly observed in difference spectra, and the use of DFT calculations provides an insight into changes induced by the variation in humidity.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp801838n