Selective reflection enhancement by controlling of surface-layering structure of inorganic nanoparticles on polymer microspheres

Abstract

Polymeric materials generally transmit or absorb UV light while weakly reflecting visible light. Treating the surface of a polymer material can increase reflectivity in the visible region. Inorganic nanoparticles, including silica and alumina, exhibit high reflectivity and light scattering at visible and UV wavelengths. Therefore, the possibility exists to absorb UV light and selectively reflect visible light by immobilizing a single layer of inorganic nanoparticles on the surface of polymer microspheres. Core-shell microspheres containing a layered shell of inorganic nanoparticles were prepared by a modified suspension polymerization method. The surface morphology of the microspheres was altered by changing the type, size, and amount of inorganic nanoparticles. The reflectivity of the microspheres was investigated via UV-Vis-NIR spectrophotometry. The packing density of the shell layer was controlled by changing the quantity of nanoparticles added. UV–visible spectroscopy indicates that the core-shell microspheres absorb UV light at wavelengths less than 380 nm and selectively reflect visible light at wavelengths greater than 400 nm. The reflectance of visible light is enhanced by changing the type and concentration of inorganic nanoparticles, and reflectance is increased by 26% relative to bare polymer microspheres. Thus, the core-shell microspheres absorb UV light and selectively reflect visible light.