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Mixed solvent effect on lithium-coordination to poly(ethylene oxide)

Authors

  • Ilhem F. Hakem,

    Corresponding author
    1. Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
    2. Faculty of Sciences, Department of Physics, Tlemcen University, Tlemcen 13000, Algeria
    • Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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  • Jyotsana Lal,

    1. IPNS, Argonne National Laboratory, Argonne, Illinois 60439
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  • Michael R. Bockstaller

    Corresponding author
    1. Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
    • Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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Abstract

This article presents a comparative study of the structure formation of poly (ethylene oxide) PEO/Li complexes in aqueous and acetonitrile solutions using small-angle neutron scattering (SANS). We demonstrate that in acetonitrile solutions, Li-cations coordinate to the ether–oxygen of the monomeric unit, and this results in charging and stretching of the polymer chains. This is found to be in contrast to aqueous solutions, where the ions remain free in solution. In particular, we demonstrate that the “binding” and “screening” regimes that were observed in case of PEO/K+ solutions in acetonitrile are also found in the respective PEO/Li+ solutions. The addition of water to solutions in acetonitrile increasingly diminishes the ion-coordination to the polymer, eventually resulting in neutral polymer chains at water contents above ϕ*water = 30% (w/v). The preferential adsorption of water on PEO in mixtures of acetonitrile and water is evidenced by the pronounced stretching of polymer chains, in particular, at a water content of ϕwater = 25% and 33.33% (w/v) where complete stretching of the chains is observed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3642–3650, 2006

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