Close-Packed Colloidal Crystalline Arrays Composed of Silica Spheres Coated with Titania

Abstract

Titania coated monodisperse silica spheres have been synthesized and fabricated as a close-packed colloidal crystalline array. We have demonstrated that the coated colloidal sphere can be used to control the peak position of the optical stop band through variation of the coating thickness. The titania coated silica spheres were prepared by the layer-by-layer assembly coating process, which reciprocally laminates the cationic polyelectrolyte and the anionic titania nanosheets on a monodisperse silica spheres, and were sintered to change the titania nanosheets to anatase. The Bragg diffraction peak of the colloidal crystalline array shifted to the long wavelength region with an increase of thickness of the titania layer. Angle-resolved reflection spectra measurements clarified that the red shift was caused by increasing of the refractive index with increase of the thickness of the layer. The current work suggests new possibilities for the creation of advanced colloidal crystalline arrays with tunable optical properties from tailored colloidal spheres.

Rayleigh like scattering from silica–titania core-shell particles and their application in protection against harmful ultraviolet rays

“…The composite particles having silica core and titania shell are widely studied. These particles are typically synthesized using techniques like layer-by-layer deposition (Caruso et al 1999(Caruso et al , 2001Nakamura et al 2005Nakamura et al , 2006, sol-gel synthesis (Holgado et al 2000;Guo et al 2003;Kim et al 2003;Liu et al 2005;El-Toni et al 2006;Lim et al 2008), laser pyrolysis (Maskrot et al 2006), heterocoagulation (Wilhelm and Stephen 2006) and flame synthesis (Hu et al 2007). Most of these methods involve multiple steps, pH control and ingredients like surfactant polyelectrolytes which makes it difficult to replicate in bulk scale.…”

Polystyrene@TiO2 core–shell microsphere colloidal crystals and nonspherical macro-porous materials

“…Recently, various core-shell microspheres have been prepared, including zinc sulfide-coated polystyrene [6,7] or silica spheres [8], core-shell latex spheres with semiconductors [9] or dyes incorporated into the shell [10], silica-core with different kind of shell [11][12][13]. Such sphere arrays could have potential applications as photonic crystals.…”

Optical properties and microstructures of colloidal crystalline arrays composed of titania nanosheets coated core-shell structured spheres

“…In this study, we demonstrate the synthesis of titania-nanosheet-coated polystyrene latex 18 or silica spheres 19 by LBL assembly coating, and the fabrication of the particles into a close-packed colloidal crystalline array by use of a fluidic cell composed of two flat glass substrates and two spacers. 20 We also report on the optical properties and microstructures of the colloidal crystalline array estimated by angle-resolved reflectance spectra measurements.…”

“…20 We also report on the optical properties and microstructures of the colloidal crystalline array estimated by angle-resolved reflectance spectra measurements. 18,19 Finally, we explore the novel prospects of using the nanosheet coating to tune the optical properties of the colloidal crystalline array for use in photonic crystal applications.…”

“…111 and n eff of the colloidal crystalline arrays derived from angle-resolved diffraction spectra 19. …”