Theoretical and experimental infrared spectra of hydrated and dehydrated sulfonated poly(ether ether ketone)

Doan, Jonathan; Kingston, Erin; Kendrick, Ian; Anderson, Kierstyn; Dimakis, Nicholas; Knauth, Philippe; Vona, Maria Luisa Di; Smotkin, Eugene S.

doi:10.1016/j.polymer.2014.07.011

Cited by 17 publications

(14 citation statements)

References 46 publications

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“…These group modes are consequent of a dissociated Nafion exchange site (sulfonate form) with C 3V local symmetry. 22,48,[51][52][53][54][55] C 1 normal mode eigenvector animation snapshots.-The dehydrated Nafion spectrum (blue) features bands at 1414 cm −1 and 910 cm −1 . These are group modes that have motional participation of the exchange group in the sulfonic acid form (C 1 local symmetry).…”

Section: Resultsmentioning

confidence: 99%

Operando Raman Micro-Spectroscopy of Polymer Electrolyte Fuel Cells

Kendrick

Fore

Doan

et al. 2016

J. Electrochem. Soc.

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Operando Raman micro-spectroscopy of the membrane electrode assembly (MEA) of a fully operating hydrogen/oxygen Nafion electrolyte fuel cell is described. Coarse depth profiling of the fuel cell system enabled appropriate positioning of the microspectroscopy laser focal point for MEA catalytic layer spectroscopy. An increase in the ionomer state-of-hydration, from oxygen reduction at the cathode, transitions ion exchange sites from the sulfonic acid to the dissociated sulfonate form. Visualization of density functional theory calculated normal mode eigenvector animations enabled assignments of Nafion side-chain vibrational bands in terms of the exchange site local symmetry: C 1 and C 3V modes correlate to the sulfonic acid and sulfonate forms respectively. The gradual transition of the MEA spectra from C 1 to C 3V modes, from the fuel cell open circuit voltage to the short circuit current respectively, demonstrate the utility of vibrational group mode assignments in terms of exchange site local symmetry.

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Section: Resultsmentioning

confidence: 99%

Operando Raman Micro-Spectroscopy of Polymer Electrolyte Fuel Cells

Kendrick

Fore

Doan

et al. 2016

J. Electrochem. Soc.

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“…1) are ideal for polymer electrolyte membrane (PEM) fuel cells because of the high proton conductivity afforded by sulfonate exchange groups (-SO 3 -) and their robust backbone structures. 1,2,3 Nafion, a perfluorinated carbon backbone with vibrationally hinged (ether link) side chains that terminate with a sulfonate exchange site, has been the dominant PEM fuel cell electrolyte for several decades. [4][5][6] Although Nafion has excellent chemical stability and proton conductivity, 4 it is expensive, has diminished conductivity above 90°C, 4,7,8 is subject to a free radical catalyzed unzipping mechanism 3 and generates fluorinated toxins when incinerated.…”

Section: Graphical Abstract Introductionmentioning

confidence: 99%

“…1,2,3 Nafion, a perfluorinated carbon backbone with vibrationally hinged (ether link) side chains that terminate with a sulfonate exchange site, has been the dominant PEM fuel cell electrolyte for several decades. [4][5][6] Although Nafion has excellent chemical stability and proton conductivity, 4 it is expensive, has diminished conductivity above 90°C, 4,7,8 is subject to a free radical catalyzed unzipping mechanism 3 and generates fluorinated toxins when incinerated. 9,10 SPEEK is lower cost, has high chemical, thermal, and mechanical stability, 1,7,11 and is environmentally friendly.…”

Section: Graphical Abstract Introductionmentioning

confidence: 99%

“…9,10 SPEEK is lower cost, has high chemical, thermal, and mechanical stability, 1,7,11 and is environmentally friendly. 12,2,3,13,14 Differences in morphology and microstructure account for functional discrepancies (e.g., proton conductivity, thermal stability) between SPEEK and Nafion. 15 SPEEK has narrower aqueous channels and dead ended aqueous confines that result in lower proton conductivity than Nafion with the same degree of sulfonation.…”

Section: Graphical Abstract Introductionmentioning

confidence: 99%

“…15 SPEEK has narrower aqueous channels and dead ended aqueous confines that result in lower proton conductivity than Nafion with the same degree of sulfonation. 3,15 While proton conductivity increases with degree of sulfonation, 14,16,17 membrane swelling also increases, diminishing mechanical strength. 1,2,12,13,15,11,18,19,20 Cross-linking mitigates much of the mechanical limitations imposed by higher degrees of sulfonation 8,13,11,18,20 to the extent that highly sulfonated cross-linked SPEEK can outperform Nafion.…”

Section: Graphical Abstract Introductionmentioning

confidence: 99%

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Infrared spectroscopy of ion-induced cross-linked sulfonated poly(ether ether ketone)

Anderson

Kingston

Romeo

et al. 2016

Polymer

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The dehydration of SPEEK-[H] (protonated sulfonated poly(ether ether ketone)) converts 3-fold symmetric (C 3V) hydrated sulfonate sites to sulfonic acid sites with no local symmetry (C 1). Like Nafion-[H], SPEEK-[H] C 3V and C 1 environments afford IR group modes (C 3V,HF (1087 cm-1); C 3V,LF (1026 cm-1) and C 1,HF (1362 cm-1); C 1,LF (904 cm-1)) due to the mechanical coupling of vibrational internal coordinates of an ether link with those of the sulfonate or sulfonic acid exchange site. C 3V and C 1 bands are inversely correlated during membrane hydration/dehydration. Hydrated SPEEK-[M] (M: Cu 2+ , Ni 2+ , Cd 2+ , Pb 2+ , Sr 2+ or Ba 2+) exhibits SPEEK-[H] C 3V bands because cation waters of hydration preclude binding to the hydrated exchange site. When cation hydration spheres are thermally stripped at high vacuum, SPEEK-[M] C 3V bands supplant SPEEK-[H] C 3V bands, inducing SPEEK cross-linking. Incomplete cross-linking is evidenced by low intensities of SPEEK-[M] C 1,HF bands. The 1362 cm-1 band intensities are inversely correlated with cation hydration enthalpies.

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A humidity-sensitive nanocomposite solid ion conductor: sulfonated poly-ether-ether-ketone in nanotubular TiO2 or ZrO2 matrix

Ruzimuradov

Braglia

Vacandio

et al. 2018

J Solid State Electrochem

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A nanocomposite solid ion conductor was prepared by infiltrating zirconia or titania nanotube arrays, made by electrochemical anodization of Zr or Ti metal, with proton-conducting sulfonated poly(ether-ether-ketone) (SPEEK) ionomer. The resulting material was characterized using scanning electron microscopy, X-ray diffraction, and infrared spectroscopy showing the successful filling of the nanotubular matrix with the ionomer. Impedance spectroscopy revealed a conductivity increase by several orders of magnitude after infiltration; furthermore, the impedance of the TiO 2 nt-SPEEK nanocomposite is very sensitive to the relative humidity. Possible applications of these ionic conducting nanocomposites include solid-state humidity sensors or heterogeneous catalytic materials.

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Theoretical and experimental infrared spectra of hydrated and dehydrated sulfonated poly(ether ether ketone)

Cited by 17 publications

References 46 publications

Operando Raman Micro-Spectroscopy of Polymer Electrolyte Fuel Cells

Operando Raman Micro-Spectroscopy of Polymer Electrolyte Fuel Cells

Infrared spectroscopy of ion-induced cross-linked sulfonated poly(ether ether ketone)

A humidity-sensitive nanocomposite solid ion conductor: sulfonated poly-ether-ether-ketone in nanotubular TiO2 or ZrO2 matrix

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