Electrochemically induced free solvent transfer in thin poly(3,4-ethylenedioxythiophene) films

In dynamic intrinsically conducting films, counterions transfer and conformational movements stimulated by the electrochemical reactions affect the free water molecules transfer. Poly(3,4-ethylenedioxythiophene) or PEDOT is included in this category. Here, p-doping of PEDOT immersed in LiClO4 aqueous solution was explored by ac-electrogravimetry. Electrochemical impedance spectroscopy combined with mass impedance spectroscopy proves useful for species identification and kinetics. For PEDOT, new equations have been developed to analyze the ac  -electrogravimetry response. Quantitatively, faster free water transfer and slower coupled ClO4−/free water transfer were separated. Free water transfer plays a key role as a “fingerprint” of conformational movements. This might respond to fundamental questions about the mechanism of PEDOT as well as their implication in technological devices based on this polymer.