H

Emeraldine Salt (Green)

Emeraldine Salt (Green)

Emeraldine Base (Blue)

Leucoemeraldine Base (Yellow)

Figure 8. Chemical transitions observed in the oxidation/reduction of polyaniline.

as a 7T-v* band at ca. 330 nm [76]. Such alkaline dedoping when performed on PAn • HA films also leads to a dramatic reduction in electrical conductivity, the EB form being an insulator.

The reversible redox switching of polyaniline films can also be readily monitored by cyclic voltammetry. For example, the cyclic voltammogram of PAn • HCl in 1 M HCl is shown in Figure 9. In the cathodic sweep, oxidation peaks are observed at ca. 0.2 and 0.7 V (vs Ag/AgCl) that may be attributed to the successive oxidations of leucoemeraldine to emeraldine to pernigraniline.

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