The oxidative chemical polymerization of o-phenylenediamine (OPDA) was studied in hydrochloric acid solution using potassium dichromate as oxidant at 5°C. The effects of potassium dichromate, hydrochloric acid, and monomer concentrations on the polymerization reaction were investigated. The order of reaction with respect to potassium dichromate, hydrochloric acid, and monomer concentration was found to be 1.011, 0.954, and 1.045, respectively. Also, the effect of temperature on the polymerization rate was studied and the apparent activation energy of the polymerization reaction was found to be 63.658 kJ/mol. The obtained polymer was characterized using XPS, IR, UV-visible, and elemental analysis. The surface morphology of the obtained polymers was characterized by X-ray diffraction and transmission electron microscopy (TEM). The TGA analysis was used to confirm the proposed structure and number of water molecules in each polymeric chain unit. The ac conductivity(σac)of (POPDA) was investigated as a function of frequency and temperature. The ac conductivity was interpreted as a power law of frequency. The frequency exponent (s) was found to be less than unity and decreased with the increase of temperature, which confirms that the correlated barrier hopping model was the dominant charge transport mechanism.

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ABSTRACT:The inhibitory effect of a 3-(10-sodium sulfonate decyloxy) aniline monomeric surfactant and the analog polymeric surfactant poly[3-(decyloxy sulfonic acid) aniline] (PC 10 ) on the corrosion of aluminum in 0.5M hydrochloric acid was studied with weight loss and potentiodynamic polarization techniques. The results show that the inhibition occurred through the adsorption of inhibitor molecules on the metal surface. The inhibition efficiency was found to increase with increasing inhibitor concentration and decrease with increasing temperature. It was found that these inhibitors acted as mixed-type inhibitors with anodic predominance. The adsorption of these compounds on the metal surface obeyed the Langmuir and Frumkin adsorption isotherms. Thermodynamic functions for both the dissolution and adsorption processes were determined. The obtained results from the weight loss and potentiodynamic polarization techniques were in a good agreement.

Inhibition effect of poly 3-dodecyloxy aniline polymeric surfactant (PC 12 H) on the corrosion of aluminum in 0.5 M HCl solution was investigated using potentiodynamic polarization technique under different experimental conditions. Inhibition efficiency and thermodynamic functions for dissolution and adsorption of PC 12 H are compared with Poly 3-(dodecyloxy sulfonic acid) aniline (PC 12 SO 3 H) to explain the effect of terminal side chain on the corrosion protection. Data show that the presence of-SO 3 H as a terminal group in PC 12 SO 3 H decreases the inhibition efficiency from 88.7%, in case of PC 12 H, to 55.1% in case of PC 12 SO 3 H. Quantum chemical calculations were performed on PC 12 H and PC 12 SO 3 H to investigate the relationship between the molecular structures and their inhibition efficiencies.

Effective electrode potential of a metal in a solution [5]. 2. Overpotential of hydrogen on the metal [6-8]. 3. Chemical and physical homogeneity of the metal surface [9]. 4. Inherent ability to form an insoluble protective film [10]. 5. Hydrogen-ion concentration (pH) in the solution [11-16].