화학공학소재연구정보센터
Journal of Applied Polymer Science, Vol.55, No.3, 399-405, 1995
Mechanism of Proton Doping in Polyaniline
The protonation processes of polyaniline (PANI) were examined by means of both UV-visible and fluorescence spectra and in situ UV-visible and in situ electron spin resonance (ESR) spectra in order to understand the mechanism of proton doping in PANI. Results obtained from UV-visible and fluorescence spectra of PANI films indicate that the protonation processes take place on the imine segment of the polyemerldine chain consistent with MacDiarmid’s suggestions. It is noted that the protonation processes consist of chemical and diffusion processes. The doping processes at the initial stage are controlled by a chemical reaction, whereas the doping processes at the middle period are dominated by a diffusion process. In situ ESR spectra of PANI films have demonstrated that a polaron is formed after protonation processes, but a splitting process of bipolaron into polaron at the measured time region was not observed. For partial protonated PANI, moreover, the fact that variation of absorption value of the peak at 630 nm with doping time supported suggestions in which a parameter of the protonation state for the molecular structure of doped PANI should be considered.