ИСТИНА

Polyaniline is one of the most popular inherently conductive polymers, due to its high conductivity and enviromental stability. Aniline oligomers are interesting objects able to selfassembly with formation of conductive ordered nanostructures and may serve as models of polyaniline. Polyaniline can be converted into its conductive form electrochemically or via acid doping. Usually, the highest conductivity is achieved in the case of polyaniline macromolecules in extended conformation self-assembled into ordered structures. The same may apply to aniline oligomers. Herein we report on solution properties of short aniline oligomers (tri- and tetraaniline) and mixture of higher oligomers doped by various (low molecular and polymeric) acids in different solvents. It was found that doping of tetraaniline or aniline oligomers mixture with polymeric acids (poly-4-styrenesulfonic or poly-2-acrylamido-2-methyl-1-propanesulfonic) in DMSO led to appearance of intensive long wavelength (>1000 nm) absorption band in UV-vis-NIR spectra. In the case of tetraaniline that band was quite sharp, being broader in the case of oligoanilines mixture. The same spectral changes were observed upon addition of large excess (orders of magnitude) of low-molecular acids (camphorsulfonic, dodecylbenzene sulfonic or hydrochloric) to tri- or tetraaniline in DMSO or DMF. The long-wavelength absorption band in the spectra of polyaniline oligomers is similar to the band observed in the spectra of highly conductive ordered polyaniline with macromolecules in extended conformation and assigned to absorption of delocalized polarons. The effect is possibly explained by conformational changes (stretching) of oligoaniline molecules or by their selfassembly with J-aggregates formation.