Structural colors from TiO2/SiO2 multilayer flakes prepared by sol–gel process

Preparation of TiO2/SiO2 multilayer flakes and their application to decorative powders were investigated. In contrast to conventional products prepared through the multicoating of core platelets, the coreless TiO2/SiO2 multilayer flakes were prepared by detaching multilayer films from their substrates. These flakes exhibited structural colors, when the optical path length of both the TiO2 and SiO2 layers are adjusted to be one fourth of the wavelength of visible light. A multicoating of more than five layers resulted in the propagation of cracks, which prevented the preparation of thick flakes. Paint films fabricated using the multilayer flakes and acrylic resins showed reflectance spectra that were comparable with those obtained for multicoatings on substrates.

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► Coreless flakes prepared from TiO2/SiO2 multilayer films show structural color.
► Paint films fabricated from our flakes and acrylic resins show structural color.
► Thick crack-free coatings must be developed to obtain the primary colors of light.