镶嵌钨硅酸的新型有机-无机纳米复合薄膜的制备及光致变色性能研究

将超分子自组装技术与Sol-gel过程相结合,制备了镶嵌Keggin结构钨硅酸的MAAM/VTEOS/TEOS纳米复合薄膜,并采用IR,XRD和TG-DSC等方法对薄膜进行了结构表征.在复合薄膜光照变蓝后,通过UV-Vis和ESR光谱对薄膜的光致变色性能及其机理进行了研究.结果表明,钨硅酸在复合网络中仍保持Keggin结构,与有机-无机复合基体中的—NH2通过氢键发生强烈的相互作用,经紫外光照后发生电荷转移,SiW12O40]4-被还原为SiW12O40]5-,同时产生氨基自由基.褪色过程则与氧气存在与否有关,实验结果表明,该薄膜具有良好的光致变色性能,对光有较快的响应恢复速度和良好的可逆重复性.

Synthesis and Photochroism of a Novel Organic-inorganic Nanocomposite Film Entrapping Tungstosilicate Acid

A novel photochromic organic-inorganic nanocomposite film was prepared through entrapping Keggin structure H_4SiW_ 12O_ 40 into MAAM/VTEOS/TEOS matrix by combining supramolecular self-assembly technology with sol-gel process. The composite film was characterized by IR, XRD and TG-DSC, and its photochromic behavior and mechanism were also studied and discussed. The transparent film changed from colorless to dark-blue under UV irradiation and was measured by UV-Vis and ESR spectra. The results indicate that SiW_ 12O_ 40] 4- anions maintain Keggin structure in the composite film and interacted strongly with _NH_2 group of the matrix via hydrogen bond. After irradiation under UV light, a hydrogen atom is transferred to a SiW_ 12O_ 40] 4- anion, and a free radical is formed at the same time. The bleaching process is closely related to the presence of O_2, and the experiments show that the composite film has excellent photochromic properties, with a short response and bleaching time and good reversibility.