Optically active SiO2/TiO2/polyacetylene multilayered nanospheres: Preparation, characterization, and application for low infrared emissivity

Optically active silica/titania/substituted polyacetylene (SiO2/TiO2/SPA) multilayered core-shell nanocomposite was successfully prepared by the combination of subsequent surface titania deposition and polymer grafting on the bare silica nanosphere. The chiral amino acid-based SPA copolymer serving as the organic shell was optically active and adopted a predominately single-handed helical conformation. The SiO2/TiO2/SPA nanospheres were characterized by Fourier transform infrared spectroscopies (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) to record the formation of the multilayered architecture and the results clearly showed that the inorganic/organic hybrid nanoparticles exhibited hierarchical multilayered core-shell construction. The SPA outer shell experienced an enhancement in thermal stability and still remained considerable optical activity after grafting to the SiO2/TiO2 nanosphere. The SiO2/TiO2/SPA nanocomposite had an infrared emissivity value (epsilon = 0.548) at the wavelength of 8-14 mu m which was much lower than each of its components. The reduced infrared emissivity values proved that the strengthened interfacial interactions originating from the coating SPA had an effective synergistic effect with the semiconductive anatase TiO2 nanoparticles on silica sphere in lowering the infrared emissivity value. (C) 2013 Elsevier B.V. All rights reserved.