Modification of polymer thin film-coated metallic layer inside acid solutions

Abstract

Modification of polystyrene (PS) thin film-coated copper (Cu) layer is studied by varying the PS layer thickness inside different acidic environments. PS-coated Cu films are exposed to acetic and hydrochloric acid environments and are investigated using UV–visible spectroscopy, atomic force microscopy, water contact angle and electrical measurements. Polymeric and metallic layer thicknesses are obtained from the X-ray reflectivity analysis. It is found that the metallic layer corrosion nearly follows an exponential decay with time and the decay time constant takes the higher values for the thicker PS films. The contact angle values, surface morphologies and in-plane current–voltage curves obtained from the films confirm that with increase in the acid concentration, corrosion of the metallic layer is much higher than the polymeric layer, as the in-plane current is reduced by a relatively higher value than the water contact angle. Penetration of the acid solution through intermolecular spacing or microscopic pores of the polymeric layer is the most probable reason for such corrosion of the metallic layer, but the removal of the polymeric layer is not favourable due to the hydrophobic effect.