Miscible polymer blends with large dynamical asymmetry: A new class of solid-state electrolytes?

We have employed broadband dielectric spectroscopy to investigate the ionic conductivity of poly(vinyl methyl ether)/polystyrene blend (PVME/PS) doped with lithium perchlorate, i.e., an archetype miscible polymer blend with large dynamical asymmetry. We have found that the temperature dependence of the ionic conductivity mimics that of the PVME segmental relaxation in PS. This results in a crossover from super-Arrhenius to Arrhenius behavior, which can be attributed to the restricted motion of confined PVME chains in PS, in analogy with polymer nanocomposites. This crossover produces, for some blends with high PS concentration that are therefore structurally solid, ionic conductivities of the same order as those of liquid PVME. This means that the miscible polymer blends are appealing candidates for making solid-state electrolytes.