In situ polymerization of polypyrrole in alcohols: Controlling deposition rate and electrical conductivity

In situ polymerization of polypyrrole (PPy) in various alcohols and water/methanol mixture solvents has been studied. The deposition rate in alcohols has been found to be slower than that in aqueous solution with the same composition, approximately 1-2 nm/min, by two orders of magnitude. On the other hand, the electrical conductivity of PPy films deposited in alcohols ranged from approximately 10-6 S/cm to approximately 1 S/cm, depending on the solvent, while that in aqueous solution was approximately 100 S/cm. These results suggest that the replacement of the solvent water with alcohols induces drastic deactivation of FeCl3 as an oxidizer. The surface morphologies of the PPy films deposited in alcohol solutions mimic those of PPy films deposited in aqueous solutions. For in situ polymerization of PPy in water/methanol mixture solvents, it has been found that the electrical conductivity as well as the deposition rate is continuously and monotonically tunable by changing the methanol content. This indicates that the utilization of a mixture solvent is a promising way to control the electrical conductivity as well as the deposition rate.