Infrared and Raman spectroscopy techniques are being applied to investigate structure within ionomer materials of interest for fuel cell applications and to aid in determinations of membrane water content. In the area of structure elucidation, two-dimensional (2D) correlation methods are being adapted to support the analysis of spectral data sets collected during hydration of fluorinated ionomer. Synchronous 2D correlation plots assist in the resolution of spectral regions complicated by overlapping bands and indicate distinctions in transformations centered within hydrophilic relative to more hydrophobic ionomer domains. Asynchronous 2D correlation plots reveal relationships in the dynamics of side chain and backbone motions that accompany changes in membrane hydration state. For the fluorinated ionomer Nafion, patterns in the synchronous and asynchronous 2D plots confirm the complexity of sulfonate-water interactions as membrane water content changes. 2D hetero-correlation spectra comparing responses of structurally related ionomer samples that vary in equivalent weight contain features that indicate side chain mobility becomes greater in low equivalent weight samples as water uptake progresses. In relation to determining membrane water content, infrared spectroscopy and multivariate analysis methods are being investigated for quantitation. Efforts to compare differences in water uptake by fluorinated ionomer materials prepared with and without inorganic filler materials will be discussed.

Vibrational spectroscopy and 2D correlation analysis applied to probe structure in ionomer membrane materials

249th National Meeting (2015)

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