The effect of dopant on structural, thermal and morphological properties of DBSA-doped polypyrrole

Polypyrrole is prepared with different molar ratios of dodecylbenzene sulfonic acid (DBSA) (0.1, 0.2, 0.3 and 0.4) by in situ chemical polymerization method. The reaction temperature was 0-5 degrees C for 24 h. The FTIR spectrum confirmed the attachment of sulfonyl group in the pyrrole structure. The intensity of polypyrrole increased with increase in sulfur content. SEM graphs revealed the granular morphology of the doped polymer surface. DBSA has had strong effect on morphology with formation of aggregated particles at higher concentrations. Higher concentration of DBSA-doped PPy shows higher thermal stability. The promotion of electron from ground state to excited state of polypyrrole is confirmed by UV spectroscopic studies. Various sizes in particle distribution of DBSA-doped PPy were analyzed by a particle size analyzer. Solubility of polypyrrole was determined at room temperature. The solubility and quantity of polypyrrole increased with higher dopant concentration. Current-voltage (I-V) characteristics were carried out over the temperature range 313-343 K, which was found to be linear. The conductivity of doped-PPy showed high conductivity at low concentration of dopant while, conductivity decreased with increasing concentration of DBSA. The higher doping level of DBSA was confirmed by elemental analysis.