Studies on ZnS and TiO2 Nanomaterials for High Reflective Coatings

Abstract

ZnS and TiO2 bulk particles are widely employed as reflective pigments. Nanocrystalline materials are very promising materials due to their unique properties such as larger surface to volume ratio and quantum confinement effect, as compared to their bulk counterparts, and are potential candidates for technological application. Therefore we are interested to investigate the properties of ZnS and TiO2 nanoparticles. In this work, synthesized ZnS and TiO2 nanoparticles have been explored to develop highly reflecting coatings. For the syntheses of ZnS and TiO2 nanoparticles, respectively the chemical precipitation and sol-gel techniques have been used. The structural, morphological and optical properties of the synthesized nanoparticles have been investigated. The techniques used for their characterization include: X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, Photoluminescence (PL), UV-visible absorption spectroscopy and UV-visible diffuse reflectance spectroscopy (DRS). The effect of the molar ratio of the precursors (L), calcination temperature, nature of capping agent and its concentration on the reflective properties of ZnS and TiO2 nanoparticles have been investigated. Attempts have been made to correlate the reflective characteristics of synthesized nanoparticles with their size, size distribution and morphology. Highly reflective coatings were developed employing these nanoparticles. Coating materials were prepared using these nanoparticles by optimizing various parameters such as pigment to binder ratio, pH, and pigment to solvent ratio. Reflectors have been developed by applying these coating materials separately to aluminium and plastic substrates with different coating thicknesses and different pigment to binder ratios. 2 The reflectors were also exposed to different light illuminations and temperatures to check their durability.