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    Please use this identifier to cite or link to this item: https://tkuir.lib.tku.edu.tw/dspace/handle/987654321/58019


    Title: Effect of particle size on the photochromic response of PWA/SiO2 nanocomposite
    Authors: Huang, Feng-Hsi;Chen, Ching-Chung;Lin, Dar-Jong;Don, Trong-Ming;Cheng, Liao-Ping
    Contributors: 淡江大學化學工程與材料工程學系
    Keywords: Photochromism;Nanocomposite;Phosphotungstic acid;Silica;Crystallization;Optical display;Smart windows
    Date: 2010-10
    Issue Date: 2011-09-28 11:55:49 (UTC+8)
    Publisher: Dordrecht: Springer Netherlands
    Abstract: A series of photochromic phosphotungstic acid (PWA)/SiO2 composites were synthesized using the sol-gel method. Depending on the feeding schedule of PWA during synthesis, the size of the formed PWA/SiO2 particles varied considerably from as small as 1.2 nm to ca. 10 nm. With decreasing silica particle size, the total contact area/interaction between SiO2 and PWA increases, as revealed by FT-IR and solid-state 29Si-NMR analyses. Particularly, when the size of PWA/SiO2 is ~1 nm, crystallization of PWA is inhibited, and PWA presents as amorphous molecular entities distributing uniformly in the SiO2 host, which is in evidence in the XRD spectroscopy and HR-TEM imaging. In contrast, substantial crystallization of PWA takes place when PWA/SiO2 particles are as large as 10 nm, in which case less amount of surface free Si-OH is available for PWA to make bonds with. Photochromism occurs activated by ultraviolet light irradiation. The rate of coloration/bleaching is found to depend strongly on the particle size of PWA/SiO2; specifically, the rate increases twice when the particle size is reduced from 10 nm to 1.2 nm.
    Relation: Journal of Nanoparticle Research 12(8), pp.2941-2950
    DOI: 10.1007/s11051-010-9884-7
    Appears in Collections:[Graduate Institute & Department of Chemical and Materials Engineering] Journal Article

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