Raman spectrometry, UV-visible-near IR and attenuated total reflection IR absorptions are used to analyze the protonation of the emeraldine form of the phenyl/ -NH 2 end-capped BQBBa tetramer and of the phenyl/ -NH 2 end-capped (BQBB) 4 a hexadecamere in strong (H 2 SO 4 or HCl), intermediate (CH 3 COOH) and weak (CH 3 OH) acids. Evolution of the pristine solution with aqueous dilution and time is analyzed in order to understand the formation of a sol of nanofilaments, which agglomerate and finally precipitate. Water in an acidic solution favors the precipitation of the corresponding emeraldine salt material, i.e. increases the degree of aggregation of the oligomeric species and the aromatic behavior of the rings. The secondary doping effect consists in intercalation of water molecules in the highly aggregated (paramagnetic) species, strongly bound to the oligomeric units and whose removal is always accompanied by elimination of the protonating agent (primary doping). The role of interchain interactions in charge carrier mobility appears more important than that of intrachain behavior.

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An inelastic neutron scattering study of polyaniline (camphorsulfonic and chloride salts, emeraldine base in the form of powder or film) from ca. 1 to 120 cm-1 shows significant changes in the compounds as a function of the temperature. Intensity and bandwidth undergo major modifications below 50 K, because of the freezing of the dynamic ring disorder. The greatest modifications were observed for camphorsulfonic acid salt. In the range from 100 to 3000 cm-1, a nonlocalized inelastic scattering process previously assigned to the “free protons” (in other words, noncovalently bonded hydrogen atoms) was also observed. Comparison with the spectra of oxidized tetramer (BQBBa), BB (diphenylamine), BBB (N,N‘-diphenyl-1,4-phenylenediamine), and BQB (-diimine) model compounds shows that, at the neutron spectrometer resolution, the dynamics of BQB already give a good basis for the aromatic ring dynamics in a polyaniline framework. Assignment of the modes is proposed in the light of low-wavenumber Raman and IR spectra. The thermal disordering of the rotational degrees of freedom appears very similar to that observed in crystalline benzene.