Multinuclear Solid-State NMR, DSC, and Conductivity Studies of Solid Polymer Electrolytes Based on Polyurethane/Poly(dimethylsiloxane) Segmented Copolymers

Abstract

Solid polymer electrolytes based on polyurethane/poly(dimethylsiloxane) segmented copolymers (PS55) have been characterized by differential scanning calorimetry (DSC), ionic conductivity, and multinuclear solid-state NMR measurements. The results of DSC measurements indicate the formation of transient cross-links between Li+ ions and the ether oxygens on complexation with LiClO4, resulting in an increase in the soft segment Tg. However, the soft segment Tg remains almost invariant at high salt concentration. There is a conductivity jump at around 310−330 K that the behavior of ionic conductivity changes from Arrehnius- to Vogel−Tamman−Fulcher (VTF)-type behavior. Below this jump temperature, the conductivity follows Arrehnius-like behavior, implying a diffusing mechanism for transport of the charge carriers where the charge carriers are decoupled from the segmental motion of the polymer chain. By contrast, the diffusion of charge carrier is assisted by the segmental motions of the polymer chains above the...