Ion transport in polymeric ionic liquids: recent developments and open questions

Polymeric ionic liquids (PILs) are an emerging class of materials that combine the attractive properties of ionic liquids with the sequence complexity and mechanical characteristics of macromolecules. While significant advances have occurred in the context of synthesis and characterization of such materials, comparatively less understanding exists on the mechanisms underlying ion transport in such materials. In this perspective article, the status of understanding in related systems of salt-doped polymer electrolytes, (non-ionic-liquid-based) single-ion polymer conductors and room temperature ionic liquids is briefly reviewed. Subsequently, some recent developments in the context of PILs are discussed to identify some open questions confronting the issue of ion transport in such materials.