Plasticized single-ion polymer conductors: conductivity, local and segmental dynamics, and interaction parameters

This paper considers high-quality conductivity data for plasticized ionomers in the context of polymer local and segmental processes. Dielectric spectroscopy was conducted on a neat PEO-based ionomer and six mixtures containing 6 wt % plasticizer with a wide range of dielectric constants. Conductivity increased dramatically but remained Vogel Fulcher Tamman (VFT)-like for all plasticized ionomers, indicating that the mechanism of ion transport was unchanged. Relaxation times of the polymer local beta and segmental alpha processes were analyzed for the plasticized ionomers, providing activation energies and relaxation strengths for the beta process and VFT fitting parameters for the alpha process. The glass transition temperature T(g) of the mixtures was found to be the critical characteristic governing conductivity, based on four criteria: VFT-like behavior of conductivity, decrease in the conductivity-segmental coupling index upon the addition of plasticizer, statistical insignificance of solvent quality (dielectric constant, donor number, and viscosity) on conductivity, and the creation of a conductivity master curve as a function of T(g)-normalized temperature.