Design and characterization of single ion conducting elastomeric networks

Ionoelastomers, or low glass-transition (Tg) polyelectrolyte networks made by polymerization and crosslinking of ionic liquid monomers, are promising materials in a variety of contexts including low-voltage electroadhesives and electromechanical transducers. We have recently studied several classes of networks containing different polymer backbones, pendent groups, and crosslinkers, and sought to understand how chemical and structural parameters of networks influence their performance using both real and reciprocal space measurements. In one example we have introduced high-mobility silicone backbones that lower Tg and improve conductivity of the materials. Remarkably, heterojunctions of polyanionic and polycationic networks show strongly temperature-dependent rectification, providing insight into the critical role of interfacial polymer dynamics in the operation of these devices. In another example, we have introduced a modular route to prepare polyanionic networks that relies on Sulfur (VI) Fluoride exchange (SuFEx) 'click' chemistry, enabling a systematic study of how ion conductivity depends on the length of short perfluorinated pendent groups. A non-monotonic dependence is identified due to the interplay between ion dissociation and aggregation. Finally, we have studied a variety of different crosslinkers as a route to tune conductivity, stiffness, and toughness of the materials.