Structural changes in polyaniline near the middle oxidation peak studied by in situ Raman spectroelectrochemistry

The transitions near the middle oxidation peak of polyaniline were studied by resonance Raman spectroelectrochemistry. Localization of polarons was observed in the potential region between first and middle oxidation peaks and connected with the coupling of the polarons into pairs – specific Raman bands were connected with separated polarons, pairs of polarons, and emeraldine states in general. In addition, a connection of the middle oxidation peak in the cyclic voltammetry of polyaniline with hydroquinone/benzoquinone defect redox transition was confirmed. These findings allow more precise determination of oxidation, protonation, and degradation level of polyaniline by resonance Raman spectroscopy. Copyright © 2017 John Wiley & Sons, Ltd.