Synthesis of poly(3-methylthiophene) in the presence of 1-(2-Pyrrolyl)-2-(2-thienyl) ethylene by electropolymerization

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 cm² for the charge transfer resistance (R_ct) for poly(3-MT) alone and 9700 ohm cm² 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.