Aqueous oxidative polymerization of 3-methoxyaniline and characterization of its polymer

Abstract

The aqueous polymerization of 3-methoxyaniline (3-OMeA) was studied using sodium dichromate as oxidant in presence of hydrochloric acid. The effect of hydrochloric acid, sodium dichromate, monomer concentration and reaction temperature 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 increasing of hydrochloric acid concentration, reaction temperature or sodium dichromate concentration but decrease with the increasing of the monomer concentration. The specific viscosity values increase with the increasing of the hydrochloric acid concentration or the 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 both sodium dichromate concentration and reaction temperature. The highest a.c.conductivity value of the obtained polymers was found when 0.0205 g mol/L of Na 2 Cr 2 O 7 , 0.8 g mol/L HCI and 0.0821 g mol/L of monomer were used in the reaction medium at 5C, the electrical conductivity and dielectric constant of this polymer sample were investigated as a function of temperature. The order of the polymerization reaction with respect to hydrochloric acid, Na 2 Cr 2 O 7 and monomer concentration was found to be 0.85, 1.36 and 0.74 respectively. The apparent activation energy (E a ) for this polymerization system was found to be 7.656 2 10 4 J/mol. The obtained poly(3-methoxyaniline) was characterized by UV-visible and IR spectroscopy, X-ray diffraction analysis and electron microscopic studies. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) results were used for the confirmation of the suggested structure.