Evaluation of Polymer Nano Pigments Performance as Corrosion Inhibitor

Inherently conducting polymers (ICPs), including polyanilines, polythiophenes and polypyrroles are organic materials that have electrical properties similar to inorganic materials such as semiconductors and metals. ICPs have the potential to replace many of these materials due to lower manufacturing costs, lower density, better processability, higher mechanical flexibility and broader chemical functionalization capabilities. The starting materials to make polyaniline are the least expensive of all the inherently conducting polymers and polyaniline is the most thermally stable of the ICPs. The two most general methods used for synthesizing polyaniline are electrochemical and chemical oxidative polymerizations. Aniline, polyaniline and their derivatives including aniline black have all been considered for use in corrosion protection [1]. Polyaniline blends (composite coatings) are usually considered to be the best choices for protecting metals from corrosion. In these blends, polyaniline is highly dispersed in a classical polymer binder and can provide many advantages [2].However, most of the organic coatings are permeable against the oxygen, water and chloride ions there are free volumes, cavities and defects inside the coating matrix generated during coating application or curing processes. Therefore, the mentioned corrosive species penetrate into the coating through the microscopic electrolyte pathways. Therefore, obtaining a long corrosion protection using organic coatings without reinforcing it by other inhibiting materials seems impossible among them incorporation of different additives, inhibitors and anti corrosive pigments are found as the most effective methods. Nanopigments doped with inhibitive species like Zn, Ni, Co and Mn has been considered as route for obtaining inhibitive performance. These nanopigments release inhibitive species like Co2+, Mn2+ and Ni2+ cations in the scratched area and protect it from corrosion through precipitating a passive film on the bare metal surface. The gole of this research is synthesized and characterization a novel anticorrosive nanopigment based on cobalt ferrite nanopigment and polyaniline - CoFe2O4 composite. The corrosion inhibition properties of the nanopigment was examined in the extract form in3.5 wt.% NaCl solution andafter inclusion into the epoxy coating by OCP analyze [3].