Synthesis and Characterization of Polycarbonate/Polystyren/Polyethylene Oxide/Zinc Sulfide Nanocomposites: Gamma Ray Induced Changes in their Optical and Color Properties

Amorphous polycarbonate (PC), amorphous polystyrene (PS), semicrystalline polyethylene oxide (PEO) and zinc sulfide (ZnS) nanoparticles (NP) were used to fabricate PC/PS/PEO/ZnS nanocomposite (NC) films. We believe that this study is novel in the area of the effect of gamma ray radiation on such NC. The synthesized ZnS NP had an average particle size of 18 nm, as indicated from the Rietveld refinement of the X-ray diffraction (XRD) scans. Samples of the PC/PS/PEO/ZnS NC films were irradiated with gamma ray doses ranging from 20 to 180 kGy. UV-vis spectroscopy and the International Commission on Illumination (CIE) color changes technique were used to investigate the resulting effects of the gamma ray irradiation on the optical and color properties of the prepared films. The light absorbance of the NC films increased as it was irradiated with the gamma ray doses up to 180 kGy, the maximum dose used. The increase in absorbance was associated with a decrease in the direct bandgap from 5.88 to 4.92 eV, and an increase of Urbach energy from 0.43 to 0.81 eV. This was attributed to the dominance of chain crosslinks. The gamma ray effects on the absorbance, extinction coefficient, refractive index and optical conductivity of the NC films were studied. The modifications in the optical properties indicated that the gamma radiation is a useful tool that allows the application of the resulting PC/PS/PEO/ZnS NC films in optoelectronic devices. Furthermore, the color differences between the pristine and irradiated films were evaluated using the CIE color differences technique. The pristine film was uncolored but showed significant color changes when irradiated with gamma radiation up to 180 kGy, the maximum dose used.