Structural analysis of micrometer-long gold nanowires using a wormlike chain model and their rheological properties

The recent growing interest in the applications of gold nanowires (AuNWs) as flexible materials has raised the fundamental issue of how their mechanical properties are related to their morphology. In this work, to address this issue, the systematic synthesis of AuNWs, their structural analysis, and their rheological investigation were demonstrated. The structural analysis of AuNWs was performed based on TEM observations and light-scattering experiments. From these observations, it was found that the length of AuNWs varies from nanometer to micrometer depending on the reaction time while a constant width of 1.6 nm is maintained. On the basis of static light-scattering experiments and a wormlike chain model, the structural parameters of AuNWs during their growth were successfully obtained. When the contour length of AuNWs reached around 5 μm, the AuNW solution showed non-Newtonian behavior and appeared to behave as a gel. Dynamic viscoelasticity measurements indicated that such viscous behavior is responsible for entanglement between AuNWs. It is concluded that AuNWs are analogous with conventional polymers in terms of both their structure and their rheological behavior.