Charge Transport and Ion Dynamics in Imidazolium-Based Homo- and Tri-Block Poly(Ionic Liquid)s*

Broadband Dielectric Spectroscopy (BDS) and Differential Scanning Calorimetry (DSC) are used to probe ion dynamics in a series of imidazolium-based tri-block copolymers, and compared to their homopolymer analogues. Two calorimetric glass transitions are observed and assigned to the charged and uncharged (polystyrene) blocks. Exchanging bromide with bis(trifluoromethylsulfonyl)amide counter-ion, a change of the glass transition temperature by over 50 K is realized, bringing forth an increase in the room-temperature dc-ionic conductivity by over six (6) orders of magnitude. By systematically varying the volume fraction of the charged block, we demonstrate that the choice of counter-ion is the key parameter influencing charge transport in these systems.