Wei FENG
,
Tierui ZHANG
,
Yan LIU
,
Ran LU
,
Cheng GUAN
,
Yingying ZHAO
,
Jiannian YAO
材料科学技术（英）
A series of photochromic hybrid films were prepared through entrapping Dawson type tungsten heteropolyoxometallates (P2W18O626-) and molybdenum heteropolyoxometallate (P2Mo18O626-) into polyacrylamide matrix. FTIR results showed that the Dawson geometry of heteropolyoxometallates is still preserved inside the composites and strong coulombic interaction is built between heteropolyoxometallates and polyacrylamide via hydrogen bonding. Irradiated with ultraviolet light, the transparent films change from colorless to blue and show reversible photochromism. The bleaching process occurs when the films are in contact with air or O2 in the dark. The molybdenum heteropolyoxometallate hybrid film has higher photochromic efficiency and slower bleaching reaction than tungsten heteropolyoxometallate hybrid film. ESR results indicated that polyacrylamide is a hydrogen donor and the photoreduced process is in accordance with the radical mechanism.
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Thin film
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Wei FENG
材料科学技术（英）
We fabricated an inorganic-polymeric photoluminescent thin film based on ZnO nanoparticles, which were grown directly in the poly(vinylpyrrolidone) (PVP) matrix. The microstructure, composition, thermal stability, and the temperature-dependent photoluminescence of the thin film were investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicated that all the ZnO nanoparticles with a polycrystalline hexagonal wurzite structure were well separated from each other and were dispersed in the polymeric matrix homogeneously and randomly. Raman spectrum (Raman) showed a typical resonant multi-phonon process within the hybrid thin film. The shifts of infrared bands for PVP in the hybrid film should be attributed to strong coulombic interaction between ZnO and polymeric matrix. The stability of the hybrid film and the effect of the perturbation of ZnO on the stability were determined by means of the thermogravimetric analysis (TG) and differential thermal analysis (DTA). The ultraviolet-visible adsorption (UV-vis) showed distinct excitonic features. The photoluminescent spectrum (PL) of the ZnO nanoparticles modified by PVP molecules showed markedly enhanced ultraviolet emission and significantly reduced green emission, which was due to the perfect surface passivation of ZnO nanoparticles. Temperature dependent photoluminescent spectrum studies suggested that the ultraviolet emission was associated with bound exciton recombination.
关键词:
Thin film
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