Effect of Pressure on Decoupling of Ionic Conductivity from Segmental Dynamics in Polymerized Ionic Liquids

摘要

We examine, for the first time, the relation between charge transport and segmental dynamics in polymerized imidazolium-based ionic liquid [PBuVIm][NTf2] in the temperature and pressure thermodynamic space. The results of ambient pressure dielectric experiments combined with temperature-modulated differential scanning calorimetry measurements have revealed a fundamental difference between the conducting properties of the examined poly-IL and its low-molecular-weight counterpart. While the dc conductivity is practically coupled to structural relaxation in aprotic ionic liquid, a significant separation between the time scale of charge and mass transport is found for the polymerized system. However, squeezing of the studied macromolecular system is found to reduce the decoupling between tau(sigma) and tau(alpha) that is attributed to significant slowing down in anions mobility under conditions of high compression. Thereby, our studies provide a fundamental understanding of the relationships between chemical structure, morphology, and ion transport properties in polymerized ionic systems diverse emerging technologies.