ABSTRACT:The electropolymerization of thiophene in the presence of 1-(2-pyrrolyl)-2-(2-thienyl) ethylene (PTE) was investigated. PTE was synthesized via Wittig reaction and by the addition of catalytic amount of PTE during the electropolymerization of thiophene, the conditions of electropolymerization of thiophene were modified. The cyclic votammograms of polythiophenes (PThs) in different conditions were obtained. The analysis of cyclic votammograms of PThs shows a considerable increase in the electroactivity and redoxability when the electropolymerization of thiophene in the presence of catalytic amount of PTE was performed. The presence of PTE during electropolymerization of thiophene leads to an increase in the rate of polymerization too. The cyclic voltammetry (CV) measurement of electron transfer ferro/ferricyanide redox system on different modified glassy carbon (GC) electrode has shown that the rate of charge transfer for PTh in the presence of PTE increased in comparison to pure PTh. The conductivity of obtained polymers was determined by electrochemical impedance spectroscopy (EIS) technique in 3.5% (w/v) NaCl solutions. The Zview(II) software was applied to the EIS to estimate the parameters of the proposed equivalent circuit, based on a physical model for the electrochemical behavior of coatings on GC. The R ct value obtained for PTh is 7667 O cm 2 . This value decreases in the presence of PTE to 4437 O cm 2 . Thus, the new film has more conductivity.

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In this study, the electropolymerization of 3-methylthiophene (3-MT) was preformed in the presence of a catalytic amount 1-(2-pyrrolyl)-2-(2-thienyl) ethylene (PTE) by cyclic voltammetry in acetonitrile as a solvent and lithium perchlorate as the electrolyte on a glassy carbon (GC) electrode. First, PTE was synthesized via the Wittig reaction. The addition of a catalytic amount of PTE during the electropolymerization of 3-MT changes the cyclic voltammograms such that the analysis of cyclic voltammograms of poly(3-MT) shows a considerable increase in the electroactivity and redoxability. Furthermore, the presence of PTE during the electropolymerization of 3-MT increases the polymerization rate. The CV measurement of the electron transfer ferro/ferricyanide redox system using different modified GC electrodes shows that the rate of charge transfer for poly(3-MT) in the presence of PTE is greater than that of poly(3-MT) alone. The conductivity of the obtained polymers was determined by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl (w/v) solutions. With the application of Zview(II) software to the EIS, we estimate the parameters of the proposed equivalent circuit, based on a physical model for the electrochemical behavior of coatings on the GC electrode, to be 15739 ohm cm 2 for the charge transfer resistance (R ct ) for poly(3-MT) alone and 9700 ohm cm 2 for poly(3-MT) in the presence of PTE. Thus, the film of poly(3-MT) formed in the presence of PTE is more conductive.

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