Use of polyaniline and its derivatives in corrosion protection of copper and silver

Abstract

This study examines the use of spin-applied conjugated polymers such as polyanilines for corrosion and dissolution protection of silver and copper. In particular, attention is given to the protection that these polymers provide under con-ditions of an applied potential and at elevated temperature. These particular conditions are those in which current inhibitors such as benzotriazole do not provide acceptable protection for the metal. A number of polyaniline derivatives are studied, including the unsubstituted parent polymer and the substituted poly-o-phenetidine both nondoped and doped, with several different protonic acids. The polymers are readily soluble in organic solvents and can be applied as thin coatings onto the metal surface. The corrosion protection of the resulting structure is determined by electrochemical and inductively coupled plasma techniques using water as an electrolyte and under varied conditions of temperature, humidity, and bias. It is found that polyaniline could either enhance the corrosion rate or produce significant corrosion protection depending on the chemical nature of the polymer backbone and the conditions in which the material is processed and doped. The poly-o-phenetidine is found to adhere well to the metal surface and provides exceptional protection both under an applied potential and at elevated temperature.