Synthesis and characterization of poly(vinyl chloride)/polyindole composites

In this study, polyindole (PIN) and poly(vinyl chloride)/polyindole (PVC/PIN) conducting composites 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 2/3. Firstly, PIN was synthesized and obtained with 78% yield. Then, PVC/PIN composites containing various amounts of PIN were synthesized. Moreover, the films of PVC and PVC/PIN composites were prepared. Mechanical properties of films were examined by stress-strain experiments. The polymers were characterized by FTIR, UV-Visible spectroscopies and conductivity measurements. Their FTIR spectra revealed that polymerization reaction was occurred by 2-3 mechanism. The conductivities of polymers at different temperatures were measured by four-probe technique. The solubility tests showed that PIN and PVC/PIN composites were relatively more soluble in polar organic solvents. Magnetic properties of the polymers were analyzed by gouy scale measurements and were found that their conducting mechanisms are of polaron and bipolaron natures. C, N, H contents of PIN, PVC and PVC/PIN composites were determined by elemental analysis. Amounts of Fe (mg/g) in PIN and PVC/PIN structures were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). Thermal properties of polymers were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and found that they have adequate thermal stability. X-ray diffraction (XRD) spectra showed the amorphous nature of the polymers. Morphological structures of PIN, PVC, PVC/PIN composites and PVC, PVC/PIN composite films were clarified using scanning electron microscopy (SEM).