Decoupling mechanical properties and ionic conductivity in conventional ion conducting polymers is challenging due to the dependence of ion motion on segmental chain dynamics. Dynamic polymer networks based on metal-ligand coordination are promising materials to accomplish such decoupling due to the transient nature of the coordination interaction. This work examines the effect of the nature and concentration of metal bis(trifluoromethylsulfonyl)imide (TFSI) salts on the mechanical properties and ionic conductivity of a poly(ethylene oxide) with tethered imidazole ligands (PIGE). Rheological analysis of PIGE containing metal salts shows dramatic tunability of the zero-shear viscosity by varying cation identity. Interestingly, impedance spectroscopy reveals comparable conductivities for monovalent, divalent and trivalent salts at constant metal-to-ligand molar ratios, suggesting some degree of decoupling is indeed achieved. Pulse-field-gradient NMR diffusion measurements indicate that the diffusion coefficient of the TFSI anion is dictated by the polymer glass transition temperature rather than concentration or counter-ion identity.

Dynamic networks based on metal-ligand bond interactions in polymeric ionic liquids

256th National Meeting (2018)

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