Influence of synthesis conditions on polypyrrole-poly(styrenesulphonate) composite electroactivity

The influence of the conditions of electrosynthesis (potential, monomer and electrolyte concentrations) on the electroactivity of polypyrrole-poly(styrenesulphonate) (PPy-PSS) composite films was determined. This electroactivity was evaluated by the charge storage ability of the polymer (amount of electrical charge stored (millicoulombs) per unit mass (milligrams) of polymer). A parallel kinetic study on PPy-PSS electrogeneration was followed. The charge storage ability of electrogenerated PPy-PSS films increased when films were electrogenerated from increasing concentrations of monomer. Films generated from increasing concentrations of polyelectrolyte or at high potentials showed lower charge storage abilities. Increasing monomer concentration favours the monomer oxidation at lower overvoltages, increases the polymerization rate at constant potential and retards the passivation-degradation processes towards high anodic overvoltages. An increase of the electrolyte concentration retards the monomer oxidation towards higher overvoltages, increases the polymerization rate at constant potential, once the monomer oxidation was initiated, and favours passivation processes. The empirical kinetics of the electrochemical generation of composite films of PPy-PSS from aqueous solution, at 800 mV (vs. SCE), were followed by ex situ ultramicrogravimetry. The orders with respect to pyrrole and NaPSS are 0.35 and 0.70 respectively.