Preparation and Properties of TiO2-Coated Hollow Glass Microspheres as Thermal Insulation Materials for Energy-Saving Buildings

Abstract

A hollow glass microsphere (HGM)/TiO2 composite hollow sphere was successfully prepared via a simple precipitation method. The TiO2 coating layers grew on the surface of the HGMs that range from 20 to 50 μm in diameter as nanoparticles with the formation of the Si‒O‒Ti bonds. The growth mechanism accounting for the formation of the TiO2 nanolayers was proposed. The morphology, composition, thermal insulation properties, and visible–near infrared (VIS–NIR) reflectance of the HGMs/TiO2 composite hollow spheres were characterized. The VIS–NIR reflectance of the HGMs/TiO2 composite hollow spheres increased by more than 30% compared to raw HGMs. The thermal conductivity of the particles is 0.058 W/(m K). The result indicates that the VIS–NIR reflectance of the composite hollow spheres is strongly influenced by the coating of TiO2. The composite hollow spheres were used as the main functional filler to prepare the organic–inorganic composite coatings. The glass substrates coated by the organic–inorganic coatings had lower thermal conductivity and higher near infrared reflectivity. Therefore, the HGMs/TiO2 composite hollow spheres can reflect most of the solar energy and effectively keep out the heat as a thermal insulation coating for energy-saving constructions.