Polymerization of Aniline in an Organic Peroxide System by the Inverted Emulsion Process

An inverted emulsion process for the synthesis of the emeraldine salt of polyaniline using a novel oxidizing agent, namely benzoyl peroxide, is described. The polymerization is carried out in a nonpolar solvent in the presence of a functionalized protonic acid (sulfosalicylic acid) as the dopant and an emulsifier (sodium lauryl sulfate). The influence of synthesis conditions such as the duration of the reaction, temperature, concentration of the reactants, etc., on the properties of polyaniline was investigated to determine the optimum conditions for the synthesis of polyaniline salt in high yield and conductivity. Using different substituted anilines and dopants, the synthesis of polyaniline derivatives was also carried out. The polymer salt and its base were characterized by a number of techniques such as UV−vis, FT-IR, FT-Raman, NMR and EPR spectroscopies, conductivity, particle size, SEM, X-ray powder diffraction, and TGA−DTA. The polyaniline−sulfosalicylic acid salt synthesized shows a conductivity of 2.53 S cm-1, which is a marked increase over the ones synthesized employing ammonium persulfate as the oxidant and sulfosalicylic acid as the dopant (2 × 10-2 S cm-1).