Electrocopolymerization, Characterization and Anticorrosive Properties of Nanostructure Poly (aniline-co-4-hydroxy phenyl acetic acid)

Abstract

In this study electrochemical deposition of nanostructure poly (aniline-co-4-hydroxy phenyl acetic acid) (PAHPA), polyaniline (PANI) and poly (4-hydroxy phenyl acetic acid) (PHPA) were carried out using cyclic voltammetry (CV) in aqueous solution of oxalic acid 0.3 M as reaction medium to achieve a protective coating for ferritic and economic 430SS in high corrosive solutions as 3.5% NaCl. In the electropolymerization of PAHPA, the monomer ratio was 1 : 1 (mol/mol). FT-IR and CV techniques were applied to characterize electrodeposited coatings. The morphological and structure analyses of the deposited films were done using scanning electron microscopy (SEM). Anticorrosive behaviors of coated steels were investigated by two techniques, potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) and were compared with protection efficiencies of PANI and PHPA. Our results showed that PAHPA coatings provided a noticeable better corrosion protection than homopolymers. The protection efficiency value for the PAHPA coated 430SS electrode was 97%, that it was higher than protection efficiencies of the hompolymers. Also effect of long immersion times on the protective films and their corrosion behaviors was studied. The PAHPA protection efficiency decreased about %3 when immersion time increased to 10 days. These results demonstrated the copolymer film can be highly corrosion resistant coating for 430SS in corrosive solutions that have chloride ions.