Synthesis, Characterization and Electrochemical Polymerization of a Comonomer Bearing Thiophene and Imidazole: The Comparison of Impedance Behavior on Different Surfaces

Abstract

In this study, a comonomer based on imidazole bearing thiophene at 2, 4 and 5-positions named of 2, 4, 5-trithiophenylimidazole (Th3-Im) was synthesized by means of Pd catalyzed Still cross coupling reaction. The product was characterized by using H-NMR and FTIR-ATR. It was electrochemically polymerized at a scan rate of 50 mV/s, applying 10–20 scans on different working electrodes such as Pt wire (radius, 1 mm), Au wire (0,5 mm), single carbon fiber (SCF) and ITO-PET (1–1 cm) from solutions containing 0.1 M Th3-Im and 0.1 M tetrabuthylammonium perchlorate (TBAP) in dichloromethane (DCM). The Th3-Im was oxidized at 0.84 V on the surface of ITO-PET. Furthermore, the effect of Poly(Th3-Im) coating on different working electrodes on impedance were investigated, and the data were collected by using electrochemical impedance spectroscopy (EIS). The double layer capacitance, CDL, value was obtained as highest on SCF surface as 0.67 mF. The morphological investigation of the polymer was carried out by using SEM and AFM. It was clearly observed that granular pieces were cumulated on electrode surface, especially on planar surface. It was found that the capacitance values of obtained coating electrodes are strongly affected by the dependence of the morphology of used electrode surface.