Ionic conduction in polyphosphazene containing oligo(oxyethylene) side chains with cyclic carbonate as terminal groups

Novel comb-type polyphosphazene derivatives with cyclic carbonate groups as the terminal function of oligo(oxyethylene) side chains [CEP] were prepared for the achievement of high ionic conductivity, when they were hybridized with LiCIO₄, in accordance with increase of permittivity. The relative permittivity of CEP turned out to be extraordinarily high, i.e. 24,6, whereas that of a similar comb-type polyphosphazene with methyl ether terminal function of side chains was less than 10 at 25°C. The [LiCIO₄(5)/CEP (95 wt.-%)] hybrid showed relatively high ionic conductivity of 7,3 · 10⁻⁶ at 25°C and 9,6 · 10⁻⁵ S · cm⁻¹ at 60°C, respectively. From the observation of the temperature dependence of ionic conductivity at 10–60°C, it was revealed that the ionic conduction obeys the Vogel-Tamman-Fulcher and Williams-Landel-Ferry equations based on the free volume theory.