Porous metal oxide microspheres with varying pore sizes

Abstract

Porous metal oxide microspheres are prepared via a process comprising forming a liquid solution or dispersion of polydisperse polymer nanoparticles and a metal oxide; forming liquid droplets from the solution or dispersion; drying the liquid droplets to provide polymer template microspheres comprising polymer nanospheres and metal oxide; and removing the polymer nanospheres from the template microspheres to provide the porous metal oxide microspheres. The porous microspheres exhibit saturated colors and are suitable as colorants for a variety of end-uses.

1 . A bulk sample of porous microspheres comprising an average diameter of from about 0.5 μm to about 100 μm, wherein the porous microspheres have two or more populations of pores each having a different average pore size. 
     
     
         2 . The bulk sample of  claim 1 , wherein the pores of each microsphere are distributed throughout the volume of the microsphere. 
     
     
         3 . The bulk sample of  claim 1 , wherein the bulk sample exhibits a color observable by the human eye 
     
     
         4 . The bulk sample of  claim 1 , wherein the bulk sample exhibits angle-independent color. 
     
     
         5 . The bulk sample of  claim 1 , wherein the average pore diameters of each population are independently selected from about 50 nm to about 999 nm. 
     
     
         6 . The porous microspheres of  claim 1 , wherein porous microspheres comprise a metal oxide selected from the group consisting of silica, titania, alumina, zirconia, ceria, iron oxides, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof. 
     
     
         7 . The porous microspheres of  claim 1 , wherein the porous microspheres are monodisperse. 
     
     
         8 . A bulk sample of porous microspheres exhibiting a color observable by the human eye, wherein the porous microspheres have two or more populations of pores each having a different average pore diameter, and wherein the porous microspheres comprise one or more light absorbers. 
     
     
         9 . The bulk sample of  claim 8 , wherein the one or more light absorbers are present from about 0.1 wt % to about 40.0 wt %, based on the total weight of the porous microspheres. 
     
     
         10 . The bulk sample of  claim 8 , wherein the two or more populations of pores consist of two populations of pores characterized by a bimodal size distribution. 
     
     
         11 . The bulk sample of  claim 8 , wherein the pores of each microsphere are distributed throughout the volume of the microsphere. 
     
     
         12 . The bulk sample of  claim 8 , wherein the bulk sample exhibits angle-independent color. 
     
     
         13 . The bulk sample of  claim 8 , wherein the average pore diameters of each population are independently selected from about 50 nm to about 999 nm. 
     
     
         14 . The bulk sample of  claim 8 , wherein the porous microspheres comprise a metal oxide selected from the group consisting of silica, titania, alumina, zirconia, ceria, iron oxides, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof. 
     
     
         15 . The bulk sample of  claim 8 , further comprising a substrate. 
     
     
         16 . The bulk sample of  claim 8 , wherein the porous microspheres are monodisperse. 
     
     
         17 . A composition selected from an aqueous formulation, an oil-based formulation, an ink, a coating formulation, a food, a plastic, a cosmetic formulation, or a material for a medical application or a security application, the composition comprising an average diameter of from about 0.5 μm to about 100 μm, wherein the porous microspheres have two or more populations of pores each having a different average pore diameter. 
     
     
         18 . The composition of  claim 17 , wherein the pores of each microsphere are distributed throughout the volume of the microsphere. 
     
     
         19 . The composition of  claim 17 , wherein the composition exhibits angle-independent color. 
     
     
         20 . The composition of  claim 17 , wherein the average pore diameters of each population are independently selected from about 50 nm to about 999 nm.