Nanogravimetric observation of unexpected ion exchange characteristics for polypyrrole film p-doping in a deep eutectic ionic liquid.

The electrochemical quartz crystal microbalance was used to determine redox-driven ion transfers accompanying p-doping of polypyrrole (PPy) films in the choline chloride-based deep eutectic ionic liquid ethaline; electroneutrality maintenance is gravimetrically dominated by choline cation transfer and this requires the presence within the undoped film of ionic liquid, when this finite reservoir of choline is exhausted there is a shift to chloride transfer.