Scanning Electron Microscopy, Spectroscopy, and Thermal Studies of Polyaniline Doped with Various Sulfonic Acids

Abstract

Inherently conducting polymer (ICP), polyaniline, was synthesized by an in situ chemical polymerization method using camphor sulfonic acid (CSA), p‐toluene sulfonic acid (p‐TSA), and dodecyl benzene sulfonic acid (DBSA). Electronic absorption spectra of doped polyanilines were recorded using m‐cresol as a solvent. The free carrier tail at a higher wavelength (characteristic of extended coil conformation) along with a sharp polaronic peak was observed predominantly in p‐TSA doped polyaniline. The intensity and sharpness of peak at 420 nm is higher in DBSA doped polyaniline. The characteristic peaks of emeraldine salt (ES) phase along with a sharp peak at 1120 cm⁻¹ representing vibration band of the dopant are observed in FT‐IR spectroscopic studies of these polymers. Scanning electron microscope (SEM) studies reveal the change in morphological features depending on the counterion used for the doping purpose. Thermal studies show a common three step decomposition pattern irrespective of the dopant used during synthesis. The room temperature conductivity is found to be higher in DBSA doped polyaniline.

Keywords:

• Polymers
• Chemical synthesis
• Spectroscopy
• Thermogravimetric analysis
• Electrical conductivity

Acknowledgment

The authors are thankful to Dr. B.K. Das, Executive Director, C‐MET, Pune for his constant encouragement.