Synthesis, characterization and assessment of poly(urethane-co-pyrrole)s derived from castor oil as anticorrosion coatings for stainless steel

Abstract

Electrically conductive and organic-solvent soluble poly(urethane-co-pyrrole)s (CPUPYs) were prepared by oxidative polymerization of pyrrole with a hydroxyl-terminated polyurethane prepolymer in the presence of ceric (IV) ammonium nitrate. Direct electrodeposition of CPUPYs from their appropriate solvent on the surface of stainless steel working electrode by continuous cycling potential between −0.8 and 1.8V vs. Ag/AgCl with a scan rate of 0.03V/s led to smooth, strongly adhered and insoluble coatings. All materials were characterized by conventional spectroscopic methods, and their physical and viscoelastic properties were evaluated. The corrosion protection properties of the CPUPYs-coated stainless steels were measured by Tafel polarization and electrochemical impedance spectroscopy. A substantial lower corrosion current, higher corrosion potential and higher charge transfer resistance values of CPUPYs-coated steels were recorded and comparisons were made with those properties of bare steel as well as parent polyurethane and neat polypyrrole-coated stainless steel. Excellent anticorrosive efficacy of newly developed CPUPYs-coated steel was achieved.