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Influence of Electrostatic Interactions on Chain Dynamics and Morphological Development in Perfluorosulfonate Ionomer Membranes

Published online by Cambridge University Press:  01 February 2011

Kirt A. Page  and
Robert B. Moore
Kirt A. Page
Affiliation:
The University of Southern Mississippi, Department of Polymer Science Hattiesburg, MS 39406–0076
Robert B. Moore
Affiliation:
The University of Southern Mississippi, Department of Polymer Science Hattiesburg, MS 39406–0076
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Abstract

Several high temperature methods of processing Nafion® have been developed using various alkylammonium ion forms of the ionomer, and the choice of counterion has been shown to have a significant effect on the thermal and mechanical properties of this material. In particular, it has been shown that neutralization gives rises to two high-temperature mechanical relaxations as observed in dynamic mechanical analysis (DMA). While several studies in the literature have attempted to explain the molecular origins of these mechanical relaxations, the assignments were based primarily on limited DMA results and have at times been contradictory. The study presented here is a fundamental investigation into the molecular origins of the thermally induced morphological relaxations and dynamics of alkylammonium forms of Nafion® membranes as studied by variable temperature small-angle x-ray scattering (SAXS) and solid-state 19F NMR spectroscopy. The intensity of the small-angle ionomer peak at ca. q = 2 nm–1 was monitored as a function of temperature for each alkylammonium neutralized sample in unoriented and oriented states. In the case of the oriented samples, the degree of anisotropic scattering from the oriented ionomer morphology was quantified using the Hermann's orientation function and monitored as a function of temperature. Changes in intensity of the ionomer peak and the Hermann's parameter as a function of temperature were shown to correlate well with relaxations observed in DMA. Several variable temperature solid-state 19F NMR techniques (including spin diffusion, side-band analysis and T1ρ experiments) were used to investigate the dynamics of the Nafion® chains. Side band analysis indicated that the side-chain is more mobile than the main chain and that the mobility is greatly affected by the size of the counterion. Changes in side-band intensity as a function of temperature were shown to correlate well with DMA data. Results from T1ρ experiments show strong counterion dependence and suggest coupled main- and side-chain motions. A two-component relaxation process was also observed for the main-chain fluorines. The results of the NMR investigations, along with the SAXS data, have led to the development of a more detailed description of the dynamics of Nafion® and the molecular origins of the mechanical relaxations. With this information, the continuing goal to determine how the strength of the electrostatic interactions in perfluorosulfonate ionomers affects the chain dynamics and developing morphology may be realized for the purpose of controlling the morphology to create more efficient ionomeric membrane materials.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 856: Symposium BB – Multicomponent Polymer Systems-Phase Behavior, Dynamics, and Applications , 2004 , BB6.4
Copyright
Copyright © Materials Research Society 2005

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References

REFERENCES

1. Grot, W. Chem.-Ing.-Tech. 1978, 50, 299.Google Scholar
2. Yeo, R. S.; Mc Breen, J.; Kissel, G.; Kulesa, F.; Srinivasan, S. J. Applied Electrochem. 1980, 10, 741.Google Scholar
3. Mauritz, K. A.; Moore, R. B. Chemical Reviews 2004.Google Scholar
4. Moore, R. B.; Cable, K. M. Polymer Preprints 1997, 38, (1), 272–273.Google Scholar
5. Nakano, Y.; Mac Knight, W. J. Macromolecules 1984, 17, 1585–1591.Google Scholar
6. Yeo, S. C.; Eisenberg, A. Journal of Applied Polymer Science 1977, 21, 875–898.Google Scholar
7. Hodge, I. M.; Eisenberg, A. Macromolecules 1978, 11, (2), 289–293.Google Scholar
8. Miura, Y.; Yoshida, H. Thermochimica Acta 1990, 163, 161–168.Google Scholar
9. Kyu, T.; Hashiyama, M.; Eisenberg, A. Canadian Journal of Chemistry 1983, 61, 680–687.Google Scholar
10. Almeida, S. H. d.; Kawano, Y. Journal of Thermal Analysis and Calorimetry 1999, 58, 569–577.Google Scholar
11. Su, S.; Mauritz, K. A. Macromolecules 1994, 27, 2079–2086.Google Scholar
12. Moore, R. B.; Martin, C. R. Macromolecules 1988, 21, 1334–1339.Google Scholar
13. Caravatti, P.; Bodenhausen, G.; Ernst, R. R. Journal of Magnetic Resonance 1983, 55, 88–103.Google Scholar
14. Cory, D. G.; Ritchey, W. M. Journal of Magnetic Resonance 1988, 80, 128–132.Google Scholar
15. Moore, R. B.; Cable, K. M.; Croley, T. L. Journal of Membrane Science 1992, 75, 7–14.Google Scholar
16. Cable, K. M. Tailoring Morphology-Property Relationships in Perfluorosulfonate Ionomers. The University of Southern Mississippi, Hattiesburg, 1996.Google Scholar
17. Chen, Q.; Schmidt-Rohr, K. Macromolecules 2004, 37, 5995–6003.Google Scholar
18. Boyle, N. G.; McBrierty, V. J.; Eisenberg, A. Macromolecules 1983, 16, 80–84.Google Scholar
19. Liu, S.-F.; Schmidt-Rohr, K. Macromolecules 2001, 34, 8416–8418.Google Scholar
20. Schlick, S.; Gebel, G.; Pineri, M.; Volino, F. Macromolecules 1991, 24, 3517–3521.Google Scholar
21. Page, K. A.; Moore, R. B. Polymer Preprints 2003, 44(1), 1144–1145.Google Scholar
22. Slade, R. C. T.; Barker, J. Solid State Ionics 1989, 35, 11–15.Google Scholar
23. Hietala, S.; Maunu, S. L.; Sundholm, F. Journal of Polymer Science: Part B: Polymer Physics 2000, 38, 3277–3284.Google Scholar
24. Gong, X.; Bandis, A.; Tao, A.; Meresi, G.; Wang, Y.; Inglefield, P. T.; Jones, A. A.; Wen, W.-Y. Polymer 2001, 42, 6485–6492.Google Scholar
25. MacMillan, B.; Sharp, A. R.; Armstrong, R. L. Polymer 1999, 40, 2481–2485.Google Scholar
26. MacMillan, B.; Sharp, A. R.; Armstrong, R. L. Polymer 1999, 40, 2471–2480.Google Scholar
27. Meresi, G.; Wang, Y.; Bandis, A.; Inglefield, P. T.; Jones, A. A.; Wen, W.-Y. Polymer 2001, 42, 6153–6160.Google Scholar
28. Giotto, M. V.; Zhang, J.; Inglefield, P. T.; Wen, W.-Y.; Jones, A. A. Macromolecules 2003, 36, 4397–4403.Google Scholar
29. Haryadi, ; Rankothge, M.; Hook, J.; Gorkom, L. v.; Moran, G. 1994.Google Scholar
30. Rankothge, M.; Hook, J.; Moran, G. Bulletin of Magnetic Resonance 18, (1–2), 137–138.Google Scholar
31. Rankothge, M.; Hook, J.; Gorkon, L. v.; Moran, G. Macromolecules 1997, 30, 4357–4362.Google Scholar
32. Kang, H. W.; Moran, G. Journal of Membrane Science 1998, 148, 173–184.Google Scholar
33. Vander Hart, D. L.; McFadden, G. B. Solid State Nuclear Magn. Reson. 1996, 7, 45–66.Google Scholar
34. Mehring, M., Principles of High Resolution NMR in Solids. 2nd ed.; SpringerVerlag: 1983; ‘Vol.’ p 342.Google Scholar