Reversible macroscopic alignment of Ag nanowires

The macroscopic arrangement of one-dimensional nanowires (NWs)/nanorods is crucial for many technological applications, because of their structure-dependent physical properties. Using a simple flow-induced alignment method, reversible structural changes between aligned and random states were demonstrated in Ag NW suspensions. The alignment of the NWs was induced under high shear rates and was stable for at least 6000 s, because of depressed Brownian motion. An aligned Ag NW suspension could return to its original random state under low shear, because of the rotation of the Ag NWs. The practical implications of flow-induced alignment are shown through the dielectric, electric, and optical properties of the dispersions. Although the alignments were not perfect, these properties still exhibited marked direction dependence. It is remarkable that the macroscopic, reversible structural change between aligned and random states and the related changes of physical properties can be easily scalable to large areas for many potential applications.