Silver nanoparticles/polyvinyl alcohol film: studies of thermal characterization, AFM and corrosion protection by electrodeposition on 304L stainless steel

A composite polymeric system consisting of silver nanoparticles and polyvinyl alcohol (nAg/PVA) was characterized by thermal analysis and compared to the two basic components, namely the silver nanoparticles (nAg) and polyvinyl alcohol (PVA). The main stage of decomposition of PVA and nAg/PVA takes place in temperature range between 210 and 325 °C, when the thermal processes consist of dehydroxylation reaction and polyene formation, macromolecular chain cleavage and oxidation reactions. The finalization of the PVA decomposition reaction takes place around 420 °C. At temperature values higher than 325 °C, the composite degradation follows another trend compared to PVA, indicating the presence of silver nanoparticles inserted into polymer matrix. Due to its adsorption and inhibitory properties and relatively good thermal stability at temperature lower than 200 °C, the nAg/PVA composite was applied as protective coating against corrosion of 304L stainless steel. Over a prolonged time, the coating can deteriorate affecting the surface characteristics. To evaluate the stainless steel surface morphology and nAg/PVA electrochemical stability over time, the atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS) were used. AFM and EIS confirmed that on the stainless steel surface, a relatively uniform and smooth composite film with a good electrochemical stability were formed, ensuring a corrosion protection performance (P%) of 81.7%.