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PudMed

Permanent URI for this collectionhttp://65.108.157.135:4000/handle/123456789/13

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Browsing PudMed by Subject "absorption"

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    Article
    Citation Count: 19
    Null Extinction of Ceria@silica Hybrid Particles: Transparent Polystyrene Composites
    (Amer Chemical Soc, 2015) Incel, Anil; Guner, Tugrul; Parlak, Onur; Demir, Mustafa M.; Demir, Mustafa
    Scattering of light in optical materials, particularly in composites based on transparent polymer and inorganic pigment nanopartides, is a chronic problem. It might originate mainly from light scattering because of a refractive index mismatch between the particles and transparent polymer matrix. Thus, the intensity of light is rapidly diminished and optical transparency is reduced. Refractive index matching between the pigment core and the surrounding transparent matrix using a secondary component at the interface (shell) has recently appeared as a promising approach to alter light scattering. Here, CeO2 (ceria) nanopartides with a diameter of 25 nm are coated with a SiO2 (silica) shell with various thicknesses in a range of 6.5-67.5 nm using the Stober method. When the hybrid core shell particles are dispersed into transparent polystyrene (PS), the transmission of the freestanding PS composite films increases over both the ultraviolet (UV) and visible region as the shell thickness increases particularly at 37.5 nm. The increase of transmission can be attributed to the reduction in the scattering coefficient of the hybrid particles. On the other hand, the particles in tetrahydrofuran (THF) absorb over UV and the intensity of absorption shows a systematic decrease as the shell thickness increases. Thus, the silica shell suppresses not only the scattering coefficient but also the molar absorptivity of the core ceria particles. The experimental results regarding the target shell thickness to develop low extinction (scattering + absorption) composites show a qualitative agreement with the predictions of Effective Medium Theory.