Simultaneous Transient Gel Behavior and Multivalent Ionic Mobility in Polymeric Ionic Liquid-Ligand Gels*

Polymeric ionic liquids form labile metal-ligand bonds with cations to delocalize and conduct multivalent metal ions in the solid state. These multifunctional interactions transiently cross-link the polymer network, leading to dramatic enhancements in the storage modulus on some timescales. Correlating the relationship between metal-ligand interaction energies, timescales, and continuum-level mechanical and conductivity properties leads to design rules for multivalent ion-conductive polymers. Oscillatory rheology experiments are used to elucidate metal-ligand coordination timescales while ionic conductivity measurements are used to both understand the timescale of crosslink motion and the mechanism of ion motion in a telechelic poly(methyl acrylate) with imidazole endgroups.