Dependence of polypyrrole bilayer deflection upon polymerization potential

•PPy bilayer actuation at different formation potentials.•EQCM measurements in correlation to polymerization potentials.•Model of “σ-dimerization” discussed to explain mixed ion actuation.

The nature of polypyrrole (PPy) is largely influenced by the potential used for its polymerization. To investigate this influence, PPy-bilayer actuators were created using different polymerization potentials in order to examine the effect of the polymerization potential on the involvement of anions and cations in the actuation process.Cyclic voltammetry and chronoamperometry methods were used to record the ion behaviour while simultaneous measurements were made of the PPy-bilayer deflection in order to characterize the PPy-bilayer actuation properties. A polymerization potential close to 0.85 V and 1.1 V produced a PPy-bilayer actuator which managed an optimum deflection in an electrolyte consisting of TBAPF6 (tetrabutyl ammonium hexaflourophosphate) in propylene carbonate (PC).Electrochemical quartz crystal microbalance (EQCM) measurements showed the degree to which solvated cations and anions are involved in the charging and discharging processes during actuation of the PPy-bilayers. The influence of anions and cations during actuation of the PPy-bilayer at reduction and oxidation is described by the model of reversible σ-dimerization.