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Radiation Modified (PEO)8ZnCl2 Polyelectrolytes and Nanocomposites

Polyethylene oxide (PEO) based solid electrolytes are gaining technological importance so improvement of their electrical and/or mechanical properties becomes increasingly important. PEO is semicrystalline polymer and ion transport is 2 to 3 orders of magnitude faster in the amorphous phase so stable PEO films with high amorphous content, low glass transition and melting temperature are preferred. That can be achieved by crosslinking that can be induced using chemical initiators, photochemically or by ionizing radiation. Radiation initiation has many advantages: it is homogeneous throughout the sample, initiation rate is independent of temperature, can be varied by varying dose rate, etc. (PEO)8ZnCl2 polyelectrolytes were prepared using unirradiated PEO or PEO crosslinked by 60Co  -radiation to selected doses, dissolving it in ethanol-water solution, adding ZnCl2 and then drying the solution. The resulting films were dried in vacuum, stored in dessicator. The space for spherulites growth can be further reduced by adding TiO2 nanograins so nanocopomposite polyelectrolytes were prepared by addition of TiO2 nanograins to the solution first. The temperature conductivity dependence of polyelectrolytes and nanocomposites was measured between 10 Hz and 1 MHz in the temperature range from room temperature to 110 °C with non-blocking Zn electrodes on an home made impedance spectrometer. DSC measurements and optical microscopy was performed in the same temperature range. FTIR spectra of PEO samples were recoreded at room temperature. The crystallinity significantly decreased with radiation dose increase due to crosslinking of PEO. The room temperature conductivities between 10-3 to 10-4 (Ω cm)-1 were achieved. Addition of nanograins increased conductivity more than can be ascribed to crystallinity reduction, possibly because of interactions of anion with nanograins.

poly(ethelene oxide); ionising radiation; polyeletrolyte; nanoparticle; nanocomposite; DSC; optical microscopy; impedance spectroscopy; FTIR

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