Improved solubility, conductivity, thermal stability and corrosion protection properties of poly(o-toluidine) synthesized via chemical polymerization

We report on the synthesis of poly(o-toluidine) (POT), a methyl-substituted derivative of PANI, by inverse emulsion polymerization. A mixture of 2-butanol and chloroform was used as dispersion medium; benzoyl peroxide as oxidant, while dodecylbenzenesulfonic acid (DBSA) was used both as dopant and as surfactant. POT was collected in its salt form and was found to be completely soluble in various organic solvents (so far highest number of solvents) such as DMSO, chloroform, toluene, THF, acetonitrile and ethanol. The synthesized polymer was characterized by cyclic voltammetry, in situ UV–Vis spectroelectrochemistry, viscosity and in situ conductance measurements, FTIR and TGA. Conductance measurements show that POT has high conductance comparable with that of electrochemically synthesized POT. The POT film dip-coated on a gold electrode was highly stable in air; no appreciable decrease in the electrochemical activity of the film occurred even when left open for 14 days in air. Thermal analysis reveals a very good thermal stability up to 513 °C. Potentiodynamic polarization measurements show that POT acts as a highly efficient corrosion protection layer on steel with 77% protection efficiency.