The Alignment of Gold Nanorods in Macroscopic Domains

The uniform alignment of nanoparticles in domains with macroscopic length scales is critical to the production of self-assembled composite metamaterials for optical applications. We describe methods of self assembly leading to films and suspensions with a high loading of orientationally ordered nanoparticles in macroscopic domains. The nanoparticles are short aspect ratio gold nanorods, with both plasmon peaks in the visible spectrum. Orientational order can be achieved via applied electric field, mechanical strain, as well as via interactions with anisotropic hosts and among nanoparticles. We have determined the orientational order in our samples from polarized absorbance measurements.