Viscosity of salt-in-polymer solutions near the glass transition temperature by penetrometry, and pseudo-macromolecule behaviour at a critical composition in NaClO₄-PPO(4000)

The first viscosity measurements of pure PPO(4000) and PPO(4000) liquid polymer electrolytes at temperatures in the vicinity of the glass transition temperature are reported. At the lower temperatures, ion pairing effects on the transport coefficients are suppressed, permitting some general trends in the dependence of the Vogel-Tammann-Fulcher (VTF) viscosity equation parameters on the salt concentration to be discerned. These are discussed in terms of ion-polymer interactions. Anomalies are noted at the composition M/O = 1/30, where some previous studies have found phase separations and these are particularly striking in the case of NaClO₄ solutions for which the VTF equation parameters cannot be reconciled with the observed calorimetric glass transition temperature. The existence of a low temperature thermoplastic (rubbery) domain, is identified and a special chain end linking mechanism, which is optimized in the NaClO₄ case, is proposed to account for it.