Kinetic Studies of the Polymerization of Substituted Aniline in Aqueous Solutions and Characterization of the Polymer Obtained

Abstract

The aqueous polymerization of m-methylaniline (mMA) was studied using sodium dichromate as oxidant in the presence of hydrochloric acid. The effect of hydrochloric acid, sodium dichromate and monomer concentration on the polymerization rate, specific viscosity of the obtained polymer and a.c.conductivity was investigated. The initial and overall reaction rates increase with the increase of hydrochloric acid concentration or sodium dichromate concentration but decrease with the increase of the monomer concentration. The specific viscosity values increase with increasing of hydrochloric acid concentration or monomer concentration, which means that the molecular weight of the polymer samples increases in the same direction. But the molecular weight decreases with the increase of sodium dichromate concentration. The highest a.c.conductivity value of the obtained polymer was found in case of using 0.023304 g mol/L of Na2Cr2O7 0.2 M HCI and 0.093225 M monomer solution in the reaction medium. The order of the polymerization reaction with respect to hydrochloric acid, Na2Cr2O7 and monomer concentration was found to be 1.3, 1.33 and —0.83 respectively. Reaction Rate = k 2[HCI]1.3[oxidant]1.33(monomer]−0.83 The apparent activation energy (E a) for this polymerization system was found to be 4.594 × 104 J/mol. The obtained poly(m-methylaniline) was characterized by uv-visible and IR spectroscopy. X-ray diffraction analysis and electron microscopy studies were carried out. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) results were used for the confirmation of the structure.