Study on the doping process of polyaniline in a thermal solution of poly(styrene sulfonic acid)

The doping process of polyaniline (PANI) was investigated in a thermal (80 °C) solution of poly(styrene sulfonic acid) (PSS). The in situ UV–vis spectra indicated that the doping process at 80 °C was completed in 1200 s, which is much faster than that at 25 °C. Through a kinetic study, the diffusion coefficient of PSS at 80 °C was estimated as 0.37 × 10−16 cm2 s−1, which is 132-fold higher than that at 25 °C (0.28 × 10−18 cm2 s−1). The specific characteristics of PANI doped with PSS (PANI–PSS) were checked using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), cyclic voltammetry (CV), and in situ UV–vis absorption spectroscopy. It was found that the low diffusion rate of PSS at 25 °C prevented the release of anions from PANI–PSS even under a negative applied potential. The electrochemical measurements showed that the charge transfer rate and electroactivity of PANI–PSS were much higher than those of PANI–H2SO4 in a neutral solution.