Theoretical and experimental infrared spectra of hydrated and dehydrated nafion. Issue 18 (23rd July 2013)

• Record Type: Journal Article
• Authors: Kendrick, Ian; Yakaboski, Adam; Kingston, Erin; Doan, Jonathan; Dimakis, Nicholas; Smotkin, Eugene S.
• Is Part Of: Journal of polymer science. Volume 51:Issue 18(2013:Sep. 15)
• Page Start: 1329
• Page End: 1334
• Publication Date: 2013-07-23
• Subjects: 547
• DOI: 10.1002/polb.23348
• Languages: English
• ISSNs: 0887-6266

Abstract

<abstract abstract-type="main"> <title>ABSTRACT</title> <p>The time‐dependent IR spectra during dehydration of fully hydrated Nafion show the reversible disappearance of the 1061 cm<sup>−1</sup> and 969 cm<sup>−1</sup> concurrent with the emergence of peaks at ∼928 cm<sup>−1</sup> and ∼1408 cm<sup>−1</sup>. The first pair of group modes is associated with a dissociated exchange group (sulfonate) with a local <italic>C<sub>3V</sub></italic> symmetry. The <italic>C<sub>3V</sub></italic> group modes shift with state‐of‐hydration: The 969 cm<sup>−1</sup> peak completely vanishes and the 1061 cm<sup>−1</sup> is reduced to a small shoulder at 1070 cm<sup>−1</sup> at end of dehydration. The <italic>C<sub>3</sub><sub>V</sub></italic> group modes are replaced by the pair of group modes of an associated exchange group (sulfonic acid) with <italic>C<sub>1</sub></italic> local symmetry. The density functional theory normal mode analysis confirms that the sulfonic acid/sulfonate site plays a dominant role in the <italic>C<sub>1</sub></italic> and <italic>C<sub>3V</sub></italic> group modes, respectively. This work clarifies the importance of assigning fluoropolymers peaks as group modes rather than traditional single functional group assignments as is often the case with the ∼1061 cm<sup>−1</sup> and ∼969 cm<sup>−1</sup><italic>C<sub>3</sub><sub>V</sub></italic> group modes. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. <bold>2013</bold>, <italic>51</italic>, 1329–1334</p> </abstract>