Electrochemical investigation of conformational rearrangements of polypyrrole deposited on Al alloys

Polypyrrole (PPy) films were electrochemically deposited on AA2024 and AA6082 Al alloys by a two-step galvanostatic procedure: (1) activation in nitric acid and (2) deposition in oxalic acid. Polymeric films were electrochemically characterized through a series of cyclovoltammetric experiments, underlining differences due to the two different substrates. Interesting effects are linked to the presence of copper in AA2024, that extracted from the alloy during the deposition, is included into the polymeric matrix increasing its quality and polymerization yield. Methods and experiments based on Otero's Electrochemically Stimulated Conformational Relaxation model (ESCR) were performed in order to investigate structural changes of the polymer in function of an applied potential. PPy on AA2024 manifests a more complex redox process, involving both cations and anions, as compared to the polymer film on AA6082 that involves only anion interchange.