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Linear coupling of alignment with transport in a polymer electrolyte membrane


Polymer electrolyte membranes (PEMs) selectively transport ions and polar molecules in a robust yet formable solid support. Tailored PEMs allow for devices such as solid-state batteries,‘artificial muscle’ actuators and reverse-osmosis water purifiers. Understanding how PEM structure and morphology relate to mobile species transport presents a challenge for designing next-generation materials. Material length scales from subnanometre1,2 to 1 μm (refs 3, 4) influence bulk properties such as ion conductivity and water transport. Here we employ multi-axis pulsed-field-gradient NMR (ref. 5) to measure diffusion anisotropy, and 2H NMR spectroscopy5,6 and synchrotron small-angle X-ray scattering7 to probe orientational order as a function of water content and of membrane stretching. Strikingly, transport anisotropy linearly depends on the degree of alignment, signifying that membrane stretching affects neither the nanometre-scale channel dimensions nor the defect structure,causing only domain reorientation. The observed reorientation of anisotropic domains without perturbation of the inherent nematic-like domain character parallels the behaviour of nematic elastomers8, promises tailored membrane conduction and potentially allows understanding of tunable shape-memory effects in PEM materials9. This quantitative understanding will drive PEM design efforts towardsoptimal membrane transport, thus enabling more efficient polymeric batteries, fuel cells, mechanical actuators and water purification.

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Figure 1: NMR spectroscopy and synchrotron SAXS of a drawn PFSI.
Figure 2: Diffusion as a function of draw ratio and water content.
Figure 3: Linear relationship between channel ordering and diffusion anisotropy.
Figure 4: Hydrophilic channel domain alignment modes for uniaxially stretched membranes.


  1. Schmidt-Rohr, K. & Chen, Q. Parallel cylindrical water nanochannels in Nafion fuel-cell membranes. Nature Mater. 7, 75–83 (2008).

    CAS  Article  Google Scholar 

  2. Mauritz, K. A. & Moore, R. B. State of understanding of Nafion. Chem. Rev. 104, 4535–4585 (2004).

    CAS  Article  Google Scholar 

  3. Ohkubo, T., Kidena, K. & Ohira, A. Determination of a micron-scale restricted structure in a perfluorinated membrane from time-dependent self-diffusion measurements. Macromolecules 41, 8688–8693 (2008).

    CAS  Article  Google Scholar 

  4. Rubatat, L., Rollet, A. L., Gebel, G. & Diat, O. Evidence of elongated polymeric aggregates in Nafion. Macromolecules 35, 4050–4055 (2002).

    CAS  Article  Google Scholar 

  5. Li, J., Wilmsmeyer, K. G. & Madsen, L. A. Anisotropic diffusion and morphology in perfluorosulfonate ionomers investigated by NMR. Macromolecules 42, 255–262 (2009).

    CAS  Article  Google Scholar 

  6. Rankothge, M., Haryadi, Moran G., Hook, J. & Vangorkom, L. Orientation effects in the deuterium NMR-spectroscopy of perfluorinated ionomer membranes. Solid State Ion. 67, 241–248 (1994).

    CAS  Article  Google Scholar 

  7. Cable, K. M., Maurtiz, K. A. & Moore, R. B. Anisotropic ionic-conductivity in uniaxially oriented perfluorosulfonate ionomers. Chem. Mater. 7, 1601–1603 (1995).

    CAS  Article  Google Scholar 

  8. Warner, M., Bladon, P. & Terentjev, E. M. Soft elasticity—deformation without resistance in liquid-crystal elastomers. J. Phys. II 4, 93–102 (1994).

    CAS  Google Scholar 

  9. Xie, T. Tunable polymer multi-shape memory effect. Nature 464, 267–270 (2010).

    CAS  Article  Google Scholar 

  10. Gierke, T. D., Munn, G. E. & Wilson, F. C. The morphology in nafion perfluorinated membrane products, as determined by wide-angle and small-angle X-ray studies. J. Polym. Sci. B 19, 1687–1704 (1981).

    CAS  Google Scholar 

  11. Moore, R. B. & Martin, C. R. Procedure for preparing solution-cast perfluorosulfonate ionomer films and membranes. Anal. Chem. 58, 2569–2570 (1986).

    CAS  Article  Google Scholar 

  12. Hensley, J. E., Way, J. D., Dec, S. F. & Abney, K. D. The effects of thermal annealing on commercial Nafion® membranes. J. Membr. Sci. 298, 190–201 (2007).

    CAS  Article  Google Scholar 

  13. Lin, J., Wu, P. H., Wycisk, R., Pintauro, P. N. & Shi, Z. Q. Properties of water in prestretched recast Nafion. Macromolecules 41, 4284–4289 (2008).

    CAS  Article  Google Scholar 

  14. van der Heijden, P. C., Rubatat, L. & Diat, O. Orientation of drawn Nafion at molecular and mesoscopic scales. Macromolecules 37, 5327–5336 (2004).

    CAS  Article  Google Scholar 

  15. Li, J., Wilmsmeyer, K. G. & Madsen, L. A. Hydrophilic channel alignment modes in perfluorosulfonate ionomers: Implications for proton transport. Macromolecules 41, 4555–4557 (2008).

    CAS  Article  Google Scholar 

  16. Rubatat, L. & Diat, O. Stretching effect on Nafion fibrillar nanostructure. Macromolecules 40, 9455–9462 (2007).

    CAS  Article  Google Scholar 

  17. Hou, J. B., Li, J. & Madsen, L. A. Anisotropy and transport in poly(arylene ether sulfone) hydrophilic–hydrophobic block copolymers. Macromolecules 43, 347–353 (2010).

    CAS  Article  Google Scholar 

  18. Park, M. J. & Balsara, N. P. Anisotropic proton conduction in aligned block copolymer electrolyte membranes at equilibrium with humid air. Macromolecules 43, 292–298 (2010).

    CAS  Article  Google Scholar 

  19. Allahyarov, E. & Taylor, P. L. Simulation study of the correlation between structure and conductivity in stretched nafion. J. Phys. Chem. B 113, 610–617 (2009).

    CAS  Article  Google Scholar 

  20. Majewski, P. W., Gopinadhan, M., Jang, W. S., Lutkenhaus, J. L. & Osuji, C. O. Anisotropic ionic conductivity in block copolymer membranes by magnetic field alignment. J. Am. Chem. Soc. 132, 17516–17522 (2010).

    CAS  Article  Google Scholar 

  21. Burnell, E. E. & de Lange, C. A. NMR of Ordered Liquids (Kluwer, 2003).

    Book  Google Scholar 

  22. Deloche, B. & Samulski, E. T. Short-range nematic-like orientational order in strained elastomers—a deuterium magnetic-resonance study. Macromolecules 14, 575–579 (1981).

    CAS  Article  Google Scholar 

  23. Zawodzinski, T. A., Springer, T. E., Davey, J., Jestel, R. & Lopez, C. et al. A comparative-study of water-uptake by and transport through ionomeric fuel-cell membranes. J. Electrochem. Soc. 140, 1981–1985 (1993).

    CAS  Article  Google Scholar 

  24. Zhang, Z. H., Marble, A. E., MacMillan, B., Promislow, K. & Martin, J. et al. Spatial and temporal mapping of water content across Nafion membranes under wetting and drying conditions. J. Magn. Reson. 194, 245–253 (2008).

    CAS  Article  Google Scholar 

  25. Terzis, A. F., Snee, P. T. & Samulski, E. T. Orientational order of water confined in anisotropic cavities. Chem. Phys. Lett. 264, 481–486 (1997).

    CAS  Article  Google Scholar 

  26. Basser, P. J., Mattiello, J. & Lebihan, D. Estimation of the effective self-diffusion tensor from the NMR spin-echo. J. Magn. Reson. B 103, 247–254 (1994).

    CAS  Article  Google Scholar 

  27. Kirkwood, J. G. The general theory of irreversible processes in solutions of macromolecules. J. Polym. Sci. 12, 1–14 (1954).

    CAS  Article  Google Scholar 

  28. Doi, M. & Edwards, S. The Theory of Polymer Dynamics (Oxford Univ.Press, 1988).

    Google Scholar 

  29. Yin, Y. G., Zhao, C. H., Kuroki, S. & Ando, I. Diffusion of rodlike polypeptides with different main-chain lengths in the thermotropic liquid crystalline state as studied by the field-gradient H-1 NMR method. Macromolecules 35, 2335–2338 (2002).

    CAS  Article  Google Scholar 

  30. Hess, S., Frenkel, D. & Allen, M. P. On the anisotropy of diffusion in nematic liquid-crystals—test of a modified affine transformation model via molecular-dynamics. Mol. Phys. 74, 765–774 (1991).

    CAS  Article  Google Scholar 

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This material is based on work supported by the National Science Foundation under award numbers DMR 0844933 and 0923107, and CBET 0756439. This material is further based on work supported in part by the US Army Research Office under Grant W911NF-07-1-0452 Ionic Liquids in Electro-Active Devices (ILEAD) MURI. Experiments at PAL were supported in part by the Ministry of Education, Science and Technology of Korea and POSTECH.

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J.L. and L.A.M. contributed major ideas to the project, collected NMR diffusion and alignment data, and wrote the primary text of the paper. J.K.P. and R.B.M. generated samples, collected SAXS data and provided interpretation and text editing.

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Correspondence to Louis A. Madsen.

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The authors declare no competing financial interests.

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Li, J., Park, J., Moore, R. et al. Linear coupling of alignment with transport in a polymer electrolyte membrane. Nature Mater 10, 507–511 (2011).

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