Kinetic Study of the Effect of the Micellar Concentration of Sodium Dodecyl Sulfate on the Spectroscopic, Morphological and Electrical Characteristics of a Polyaniline Prepared by a Hybrid Micro-Nanoemulsion Bi-Micellar Polymerization Technique

Abstract

In the present work a study of the micro-nanoemulsion polymerization of aniline (ANI) was undertaken by employing two kinds of micelles as binary dopants, one type based on one of three sulfonic acids, dodecyl benzene sulfonic acid (DBSA), naphthalene-disulfonic acid (NDSA) or para-toluene sulfonic acid (TSA)), and the other based on an added surfactant (sodium dodecyl sulfate (SDS)). The effects of the important parameters, SDS concentration, sulfonic acid nature and temperature, were studied. The resulting polyaniline salts were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR), Raman and X-ray fluorescence (XRF) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and by a standard electrical resistance four-probe method. The SDS concentration had the predominant role in the doping level, thereby affecting the resultant conductivity. The present investigation revealed that the key parameters, SDS concentration, temperature and sulfur content, in the final product were influential in determining the PANI properties. The oxidation degree increased with a decrease in temperature of polymerization. It was found that the polymerization yield and electrical conductivity of the polyaniline salts PANI-NDSA-SDS and PANI-DBSA-SDS prepared with the critical micelle concentration (CMC) had the highest values and the polymer became thermally more stable. The highest electrical conductivity value obtained was 92.25 S/cm for PANI-NDSA-SDS prepared at 20 °C with the CMC of the SDS.