Regeneration of polyaniline during acid-base treatment of the samples prepared by fractionating vacuum thermal deposition

Summary form only given. Polyaniline (PAN) layers have wide prospects of application in electrochromic devices, in photoelectrochemical power cells, in light-emitting diodes etc. One of the methods of PAN films preparation is vacuum thermal deposition. Vacuum thermal evaporation of a single portion of chemically synthesized PAN base powder has been performed step-by-step within four temperature intervals falling into 240-450/spl deg/C range. The vapor was deposited on quartz and SnO/sub 2/ -glass substrates, each fraction being deposited on a separate substrate. The samples obtained has been subjected to cyclic contrast acid-base treatment, and UV-Vis spectra of the fractions after each treatment cycle were registered. The spectra of the as-deposited fractions appeared to have little in common with conventional PAN spectra. Arising of the absorption bands essential for conventional PAN spectra has been found to occur for some of the fractions only after the above treatment. This is apparently due to recombination of PAN oligomer radical fragments, formed in the course of the evaporation, resulting in restoration of PAN macromolecule structure. The recombination may be intensified by conformational changes during the acid-base treatment. Cyclic voltammetry curves for the most PAN-like fractions resemble this ones for conventional PAN. The conductivity reachs its maximum for the most polyaniline like fractions, but it´s five orders less than this one for the electrochemically synthesised polyaniline.