Methods for charge-titrating assembly of partially metallized nanoparticles, and metamaterials produced therefrom

Abstract

Variations provide a metamaterial comprising a plurality of metamaterial repeat units containing a surface-patterned nanoparticle or microparticle that is coated with a metal in a surface pattern. The surface-patterned particle may include a dielectric material or a semiconductor material partially or fully coated with metal(s). In some embodiments, the surface-patterned particles are split ring resonators. Some variations provide a method of making a metamaterial, the method comprising: metallizing surfaces of particles, wherein particles are coated with metal(s) in a surface pattern; dispersing surface-patterned particles in a liquid solution at a starting pH; introducing a triggerable pH-control substance capable of generating an acid or base; and triggering the pH-control substance to generate an acid or base, thereby adjusting the solution pH to a titrated pH. The zeta potential is closer to zero at the titrated pH compared to the starting pH, causing the surface-patterned particles to assemble into a metamaterial.

What is claimed is: 
     
         1 . A metamaterial comprising a plurality of metamaterial repeat units, wherein each of said metamaterial repeat units comprises a surface-patterned particle that is a base particle coated with one or more metals in a surface pattern, and wherein said surface-patterned particle is characterized by an average particle size from about 1 nanometer to about 100 microns. 
     
     
         2 . The metamaterial of  claim 1 , wherein said surface-patterned particle has a geometry selected from the group consisting of round, cylindrical, elliptical, cubic, diamond-shaped, bipyramidal, hexagonal prism, and combinations thereof. 
     
     
         3 . The metamaterial of  claim 1 , wherein said base particle comprises a dielectric material, a semiconductor material, or a combination thereof. 
     
     
         4 . The metamaterial of  claim 1 , wherein said base particle comprises a material selected from the group consisting of oxides, sulfides, phosphides, selenides, tellurides, fluorides, arsenides, silicon, and combinations thereof. 
     
     
         5 . The metamaterial of  claim 1 , wherein said one or more metals are selected from the group consisting of gold, silver, copper, nickel, aluminum, and combinations thereof. 
     
     
         6 . The metamaterial of  claim 1 , wherein said surface-patterned particle is partially coated with said one or more metals. 
     
     
         7 . The metamaterial of  claim 1 , wherein said surface-patterned particle is fully coated with said one or more metals. 
     
     
         8 . The metamaterial of  claim 1 , wherein said surface-patterned particle is a ring resonator. 
     
     
         9 . The metamaterial of  claim 1 , wherein said surface-patterned particle is a split ring resonator. 
     
     
         10 . The metamaterial of  claim 1 , wherein said metamaterial is a periodic three-dimensional array of said metamaterial repeat units. 
     
     
         11 . The metamaterial of  claim 1 , wherein said metamaterial repeat units have a packing density of at least 50 vol % within said metamaterial. 
     
     
         12 . The metamaterial of  claim 1 , wherein said metamaterial contains at least 10 3  of said metamaterial repeat units. 
     
     
         13 . The metamaterial of  claim 1 , wherein said metamaterial is essentially free of organic molecules chemically bonded or physically adsorbed to said surface-patterned particles. 
     
     
         14 . The metamaterial of  claim 1 , wherein said metamaterial repeat units contain cylindrical or ellipsoidal structures with an average length-to-width ratio of about 1.5 or higher. 
     
     
         15 . The metamaterial of  claim 1 , wherein said metamaterial is present in a system selected from the group consisting of photonic systems, magnets, optical devices, optical filters, optical-absorbing systems, cloaking systems, electronic devices, electrochemical systems, and computers.