Studies on ion dynamics of polymerized ionic liquids through the free volume theory.

Over the last decade, the volume has been envisioned as a critical variable controlling the dynamics of glass-forming systems in general, and charge transport of ionic conductors in particular. Herein, we use theoretical and experimental approaches to investigate the volume effects in a specific 1,2,3-triazolium-based poly(ionic liquid) (PIL) at both the macro and nano scales. The size of the local free volume cavity in the studied system was determined by positron annihilation lifetime spectroscopy (PALS). On the other hand, the theoretical approach enabled us to estimate the hard-core volume (V hc) and thus free volume (V f) in the studied PIL. Since the experimental value determined for V f is relatively large it can be considered as the main factor controlling the superionic properties of this material. Furthermore, the analysis of specific volume and relaxation dynamics in T - P plane in terms of the locally correlated lattice (LCL) and cooperative free volume (CFV) models shows that none of them works for the studied system. Image 1 • Investigations into the size of local free volume cavity of polymerized ionic liquids by means of PALS. • Studies on the effect of free volume on ion dynamics in polymerized ionic liquids. • The failure of the LCL and CFV models in case of ion-conducting polymers. [ABSTRACT FROM AUTHOR]