Comparative electrochemical performance of electrodeposited polypyrrole in protic and aprotic ionic liquids

• Electropolimerization in ionic liquids.
• Ionic exchange in ionic liquid electrolytes.
• Electrochemical and electrochromic behavior of polypyrrole in ionic liquids.

Polypyrrole (Ppy) thin films were obtained by pyrrole (py) electropolymerization in ionic liquid (IL) media. The charge compensation dynamics as well as the electrochromic behavior of the obtained films were studied in two ILs with similar structures, being one containing –CH3 (aprotic IL) and the other containing –H (protic IL) attached to the ethylimidazolium cation. The results obtained with quartz crystal microbalance with dissipation combined with cyclic voltammetry have shown that in spite of the presence of protons in the PIL, which could favor both electropolymerization and electrochemistry of Ppy in this media, these processes are more effective in the aprotic IL, leading us to conclude that other factors must be take into account when choosing the most appropriated IL as electrolyte. Also, electrochemical reactions in both ILs were successfully associated to the transformation of chromogenic species by evaluating the electrochromic activity of the polymeric films.