ИСТИНА

Conductive polymers such as polyaniline (PANI) and poly-3,4-ethylenedioxythiophene (PEDOT) were prepared by electrochemical polymerization of aniline and 3,4-ethylenedioxythiophene (EDOT), respectively, in the presence of sulphonated polyelectrolytes with different structure and different molecular weight. The following flexible-chain polyelectrolytes were used: poly(styrene-4-sulfonic acid) (PSSA), poly-(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA), and their sodium salts in the case of EDOT. The aniline and EDOT electropolymerization was performed in potentiostatic (PS), galvanostatic (GS) and cyclic voltammetry (CV) regimes. To elucidate the role of polyelectrolyte in the synthesis we have performed in situ Raman and UV-Vis spectroscopy studies during aniline and EDOT electropolymerization. The films obtained were characterized by cyclic voltammetry, Vis-NIR and Raman spectroelectrochemistry and AFM-microscopy. The synthesis of PANI in the presence of high-molecular-weight (HMW) polyelectrolytes proceeds as the traditional electrodeposition in the inorganic acid with low pH. Crucial differences in the kinetics of synthesis and the properties of prepared films were observed in the case of electrochemical polymerization of aniline in the presence of low-molecular-weight (LMW) PAMPSA and, to a lesser degree, in PSSA (Fig. 1a). In case of using LMW polyelectrolytes the aniline electropolymerization has non-autocatalytic character in PS and GS regimes, as well appearance of the “middle peak” during CV polymerization. This leads to defect structure of PANI films obtained. On the contrary, the electropolymerization of EDOT in the presence of HMW and LMW polyelectrolytes proceeds as the traditional electrodeposition in organic media. But the electropolymerization rate is higher in PS regime and the potential of polymerization in GS regime is lower in the presence of low-molecular-weight PSSNa (Fig.1b). Moreover the rate of EDOT electropolymerization depends on the form (acid or salt) of polyelectrolyte. The dependence of polymer properties and character of the synthesis on polyelectrolyte structure and its molecular weight is discussed considering peculiarities of the aniline and EDOT distribution in the solution of polyelectrolyte with different hydrophilicity, conformational state and spatial distribution of sulfonic groups in polyelectrolyte coils.