Spectrophotometric investigation of co-solvent induced doping of PCA-protonated polyaniline solutions

Protonation of polyaniline emeraldine base (PANI EB) was carried out by using different molar concentrations (0.1–0.5 M) of 2-pyrrolidone-5-carboxylic acid (PCA) in dimethylformamide (DMF) solvent. A dedoping effect was observed by UV–vis spectroscopic analysis when doped PANI solutions were diluted with DMF. This effect is due to interaction between the dopant and the solvent which leads to dedoping. It was observed that the dedoping effect was minimized on diluting with methanol. Further on methanol addition a dilution-induced partial doping effect was observed. It is assumed that this may be due to hydrogen bonding interactions between the two solvents.