Advanced metrology and molecular dynamics simulations for quantifying counterion condensation in block copolymer electrolyte thin films*

Ionic conductivity is an important property of polymer electrolyte membranes and electrode binders. The impact of counterion condensation, a proxy for the extent and strength of ionic group dissociation in polymer electrolytes, on ionic conductivity has received less attention and is not clearly known. This talk highlights our effort to quantify counterion condensation in self-assembled block copolymer electrolyte (BCE) thin films. Advanced metrology (GI-SAXS, QCM, ICP-OES, and LC-MS) were applied to quantify counterion condensation in BCEs. These techniques identified the Donnan concentration during ion-partitioning experiments and determined the activity coefficients of these ions in thin films. Experimental results were compared against the Gibbs-Donnan Model and Manning’s Theory of Counterion Condensation, as well as classical molecular dynamics simulations. The agreements and differences between the experimental and modeling techniques will be presented and discussed.