X-ray photoelectron spectroscopy study of electrically conducting polyaniline/polyimide blends

The changes in protonation level ([N+]/[N] ratio), doping state, and conjugation condition for polyaniline-complexes/polyamic acid (PANI-complexes/PAA) blends and their thermally cured polyaniline-complexes/polyimide (PANI-complexes/PI) have been assessed by X-ray photoelectron spectroscopy and UV–Vis spectroscopy. It was suggested that the protonation levels were predominantly associated with dopants that show different protonation ability. By XPS N1s peak convolution, it was found that thermal treatment of blends led to dedoping when the curing temperature reached 250°C. However, stability of protonation state of blends against thermal curing was higher than pure PANI-complexes. Dopants in the blends also affect the distribution of N+ species and thermal stability to curing. Mild thermal treatment (180°C) led to the increase of conjugation length ascribing to the increased order of polymer chain, although their protonation levels were not increased.