Polypyrrole plus polyacrylate composites: Electrogeneration

Suitable conditions for the electrogeneration of polypyrrole + polyacrylate electroactive composites were established. In the presence of sodium polyacrylate, pyrrole oxidation is initiated at 350 mV from aqueous solution. Higher ratios of polyacrylate/pyrrole concentrations than 0.03 give very thin and passive films; thick and electroactive films are obtained from lower concentration ratios, as was proved by voltammetric, potentiometric and chronoamperometric studies from either different concentrations of polyelectrolyte or different concentrations of monomer. Films of composite electrogenerated at constant polarization times and increasing constant potentials, in the range between 700 and 3000 mV, show increasing masses, increasing productivities of the polymerization charge, decreasing ability to store charge per milligram of composite, and a practically constant ratio between polymerization charge and charge consumed to oxidize the film until 1800 mV. Masses of films generated at different polymerization times and constant potential (800 mV) follow straight lines, which allow kinetic studies. Charge storage efficiencies increase for films generated at long polarization times, while productivities remain constant (around 0.55 mg mC(-1)). Increasing passivities were attributed to strong interaction-adsorption between the electrode and polyacrylate anions during polymerization.