UV–Vis spectroscopy is one technique used to study the electronic
absorption of conducting polymers that is useful for
investigating the oxidation and doping state of the polymer
backbone.
Pure PANI has two absorption peaks (shown in
inset of Fig. 3). The optical absorption spectra of the sulphonic
acid-doped PANI–PVA blends are shown in Fig. 3, and peaks
are listed in Table 2. As presented in Table 2, the absorption
peaks for pure PANI exhibit two peaks at 274 nm and at
396 nm, whereas pure PVA only exhibits one absorption peak
at 294 nm. In the sulphonic acid-doped PANI–PVA blends,
the absorption peaks are observed at 290–276 nm and 438–
420 nm, corresponding to the pfi p* of benzenoid rings and
localised polarons (quinoid, Q), respectively.