Synthesis and characterization of polythiophene and polyindole based composites and copolymers

In this study, homopolymers of polythiophene (PT), polyindole (PIN) and polythiophene and polyindole based composites and copolymers were synthesized by chemical polymerization. In the experiments, iron (III) chloride was used as an oxidant and the molar ratio of monomer/oxidant was taken as 1/3. Firstly, PT and PIN were synthesized. Then, PT/PIN(53%) and PIN/PT(47%) composites were synthesized by changing the synthesis order of PT and PIN. Besides, at the synthesis conditions of polythiophene and polyindole and at the room temperature using same ratios, from thiophene and indole monomers the copolymers syntheses were carried out. The synthesized products were characterized by FTIR, UV-vis spectroscopies and conductivity measurements. The conductivities of polymers, composites and copolymers at room temperature and different temperatures were measured by four probe technique. Among the polymers, composites and copolymers, PT-PIN copolymer the highest conductivity with a value of 0.28 S cm-1. It was observed that the conductivities of PT, PIN, composites and copolymers increased with increasing temperature. From FTIR analyses, it was suggested that the polymerization reaction of polythiophene and polyindole occurred via 2,5 and 2,3 propagation mechanisms, respectively. The solubility tests showed that the polymers had very low soluble properties. Magnetic properties of the polymers, composites and copolymers were analyzed by Gouy scale measurements and were found that their conductivity mechanisms are of bipolaron nature. C, N, H and S contents of PT, PIN, the composites and copolymers were determined by elemental analysis. Generally, it was found out that calculated and experimental values were compatible with each other. Amount of Fe (mg/g) in the samples were determined by atomic absorption spectroscopy (AAS). The thermal properties of the polymers, composites and copolymers were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and found that they have quite good thermal stabilities. X-ray diffraction (XRD) spectra showed the amorphous nature of the materials. Morphological structures of the samples were clarified using scanning electron microscopy (SEM).