Researchers have developed a method to self-assemble close to perfect structures of gold nanoparticles. The gold nanoparticles were grafted with polymer chains into 2D supercrystals by controlling salt concentration. The materials were characterized using high-resolution synchrotron surface X-ray scattering methods, including grazing incidence small angle X-ray scattering and X-ray reflectivity, at the Advanced Photon Source, a U.S. Department of Energy, Office of Science User Facility. At low salt concentrations, no ordered structures exist. As salt concentration is increased, 2D hexagonal order develops, and above a threshold concentration highly ordered hexagonal crystallinity is observed. The size of the crystalline unit cell can be varied by changing the salt concentration. The novel approach of using salt and polymers for self-assembly is general and can be used to assemble other functionalized nanoparticles. In addition, the approach is robust, scalable, and allows for a wide range of unit cell tunability, which may allow the design of novel materials for optical properties.
Salt-induced 2D hexagonal superlattices of polyethylene-glycol functionalize gold nanoparticles at the vapor-liquid interface.
Macroscopic and Tunable Nanoparticle Superlattices