Electronic and vibrational changes induced by different acidic vapors in polyaniline

We present a comparative study of conductive salt of polyaniline, i. e., polyemeraldine doped with HCl vapor or with HCSA upon m-cresol vapor. Raman scattering, UV-Vis-nir absorption and conductivity measurements vs acid vapor time exposure have been made. In fact, interesting and similar results have been observed by UV-Vis-nir on thin film of polyemeraldine base doped with HCl vapor [1] and on PANI-HCSA thin films deposited from chloroform and exposed to m-cresol vapor [2]. Raman spectra were recorded with the excitation lines from the blue range (λexc = 457.9 nm) to the red region (λexc = 676.4 nm). As expected, results are clearly affected during both processes. These modifications can be interpreted in terms of electronic and conformational changes of the chains, consistent with an increase of the conjugation length and of the delocalization of polarons.