Electrochemical and Raman spectroscopic study of polyaniline; influence of the potential on the degradation of polyaniline

Raman based pH measurements with polyaniline

“…As the film thickness increases, the ES to pernigraniline base (PNB) transition also becomes visible in the CV at E pa,3 /E pc,3 = $820/ 790 mV. This transition results in a degradation product of the PANI film (hydroquinone-benzoquinone couple), which can be observed as a minor redox process at E pa,2 / E pc,2 = $590/530 mV [34]. The PANI film was characterized in 1.0 M HCl between À0.2 and 0.6 V after the polymerization ( Fig.…”

Electrosynthesis and characterisation of poly(N-methylaniline) in organic solvents

“…1(b), the first couple at E pa,1 @ 275 mV and the third couple at E pa,3 @ 766 mV (v = 50 mV/s) can be ascribed to the LE-E and the E-PN transitions of PNMA (Scheme 1) [5]. As for PANI [28], the second redox couple at E pa,2 @ 516 mV has been interpreted by Sivakumar and Saraswathi in an aqueous solution as associated with the hydroquinone-benzoquinone degradation product [17]. The anodic oxidation peak potentials of the PNMA film observed in this study are very similar to the peak potentials of PNMA obtained by Sivakumar and Saraswathi in an aqueous solution at pH 0.…”

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

“…Three oxidation peaks are detected by cyclic voltammetry of PANI; ‘first’ peak belongs to the oxidation from leucoemeraldine to emeraldine and the ‘second’ to the transition from emeraldine to pernigraniline and chain growth . The current of the ‘middle’ peak is typically observed in early stages of PANI film growth, decreases with film thickness, and increases again with oxidative degradation . It was attributed to the oxidation of the products of hydrolysis and hydroquinones or to the phenazine‐like cross‐linked structures …”