Ionic conduction in polyphosphazene solids and gels:: 13C, 31P, and 15N NMR spectroscopy and molecular dynamics simulations

Polyphosphazene single-substituent polymers were synthesized with the general formula [NP(OCH2CH2OCH2CH2XCH3)(2)] where X = oxygen for polymer 5 or X = sulfur for polymer 6. Characterization of these materials made use of H-1, C-13, N-15, and P-31 nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, gel permeation chromatography, and elemental microanalysis. The polymers were complexed with LiSO3CF3 and AgSO3CF3 and examined both as solid electrolyte media and in the presence of dimethylformamide solvent. The ionic conductivities of these materials were determined at 25 degrees C through the use of complex impedance analysis. The mechanism of ionic conduction in the polymer-salt complexes was probed through an examination of C-13, P-31, and N-15 NMR shifts and C-13 NMR spin-lattice relaxation times (T-1) for d(7)-DMF solutions. Molecular dynamics simulations were also carried out in order to investigate the interactions within the polymer-salt-DMF complexes.