Dielectric Relaxation and Conductivity Study of Polytetrafluorene‐Ethyl Ionomers

Dielectric relaxation measurement was performed on the H2O containing ionomer from Dow Chemical with poly‐tetrafluoro‐ethylene (PTFE) backbones. The temperature Cole‐Cole plot of the complex permittivity was employed to separate the dielectric relaxation of the polar groups from the conducting ions at low temperatures. The resulting conductivities reached 10−2 S/cm at 295 K, comparable to that of Nafion®. The temperature dependence of the dc resistance was found to be non‐Arrhenius and fitted by the Vogel Tamman‐Fulcher expression T1/2exp(Qc/(T−T0)) , yielding a T0 of 90 K and Qc of 0.12 eV. The difference between this T0 and the Tg is much larger (over 250 K) than that of PEO (≈50 K). The polar‐group relaxation extracted at temperatures between 90–160 K produced an activation energy of 0.075 eV. This relaxation is attributed to the restricted water molecules and pendant groups of PTFE affecting the ion transport.