An electrochemical method to rapidly assess the environmental risk of silver release from nanowire transparent conductive films

Abstract

Silver nanowires (AgNW) are new nanomaterials designed to be incorporated into transparent conductive films in electronics, microelectrodes, heated surfaces and others. Although in these films, the AgNW are generally protected by a coating material, a risk for release of silver at all stages of the nanoproduct life cycle does exist due to corrodibility of the metal. Since ionic and nanoparticulate Ag represent a toxicological risk for a large number of living cells, there is a need for quantifying the potential Ag release from these product components. We developed an electrochemical method to evaluate possible corrosion activity of silver in AgNW transparent conductive films (TCFs) and concomitant Ag+ release. A polysiloxane polymer was used as protective coating of AgNW TCFs. A consistent correlation is observed between the degree of corrosion and the coatings' characteristics, in particular the thicknesses. A major advantage of the new approach, compared to classical aging studies, is the short experimentation time: 20 min are sufficient for a diagnostic result. The method is an accelerated corrosion and release test. It is environmentally sound methodology with use of very low electric power and with no harmful reagents. A particularly attractive application could be in the field of environmental risk assessment of metals from portable electronics and biosensors.