The Role of Polymer–Ion Interaction Strength on the Viscoelasticity and Conductivity of Solvent-Free Polymer Electrolytes
Seamus D. Jones, Nicole S. Schauser, Glenn H. Fredrickson, Rachel A. Segalman
Abstract
Metal–ligand coordinating polymers utilize labile bonds between polymer-bound ligands and free cations to delocalize and conduct mono and multivalent metal ions in the solid state. These interactions simultaneously act as reversible cross-links, leading to delayed terminal relaxation as measured by oscillatory rheology. Well-controlled poly(methyl acrylate)s with imidazole chain ends are synthesized as model polymers to obtain metal–ligand bond lifetimes and to investigate design rules for solid polymer electrolytes. Through changes in identity of the metal species, metal–ligand bond lifetimes are varied over nearly two orders of magnitude. Scaling analysis demonstrates a correlation between the bond lifetime and the ionic conductivity, suggesting a hierarchical conduction mechanism that involves interplay of polymer segmental motion with the dissociation of metal–ligand bonds. This suggests an alternative means to enhance long-range ionic transport that is partially decoupled from efforts to enhance the segmental mobility of ion-conducting polymers.