Sodium Ion Conduction of Perfluorosulfonate Ionomer/ Poly(oxyethylene) Composite Films

A composite film of Na⁺-form Nafion and diendoacetylated poly(osyethylene) (M_w = 400) (POE₄₀₀e) was cast from a dimethylformamide solution at 120 °C. The ionic conductivity of this thin film was measured. The resulting film showed good flexibility, transparency, and no leakage of POE_400E up to the POE incorporation of 55 wt %. At this composition, sodium ionic conductivity was 1.0 ✕ 10^‒6 S cm^‒1, which is relatively high as a single-ion conductor because of the high dissociation of the sodium perfluorosulfonate groups. The ionic conductivity increases with POE incorporation. This can be explained from a decrease in the glass transition temperature (T_g) of POE regions and the connection of ion clusters swollen by POE.