钨磷酸/聚乙烯基吡咯烷酮纳米复合膜的光致变色性能

Study on the photochromism of phosphotungstic acid/polyviny pyrrolidone nanocomposite films

制备了一系列不同配比的钨磷酸/聚乙烯基吡咯烷酮纳米复合薄膜.通过原子力显微镜、红外光谱和紫外-可见吸收光谱对复合薄膜的结构和光致变色性能进行了研究.AFM结果表明,复合前后聚乙烯基吡咯烷酮表面形貌因杂多酸的掺杂而发生了显著变化.红外光谱分析结果表明,Keggin结构钨磷酸和聚乙烯基吡咯烷酮分子的基本结构在复合薄膜中仍然存在,乙烯基吡咯烷酮分子基团质子化后与杂多阴离子成盐,形成电荷转移桥.在紫外光照射下,复合薄膜由无色变为蓝色,在空气中暗处放置后复合膜重新恢复为无色.复合膜的升色速度和褪色速度均随着杂多酸含量的增加而加快.结果表明,杂多酸含量对复合膜的光致变色性能存在显著影响.

A series of polyvinyl Pyrrolidone （PVPd） composite films with different phosphotungstic acid （PWA） content have been prepared. The structure and photochromic behavior of the composite thin films were studied with atomic force microscopy （AFM）, FT- infrared spectroscopy （FT- IR） and ultravioletvisible spectra （UV-vis）. AFM images indicated that surface topography of the polymer matrix charged after adding PWA. FT-IR results showed that the Keggin geometry of PWA and PVPd were still preserved inside the PWA/PVPd composite thin films and the salts were formed by combining the ion based on the N atoms in the polymeric molecules and H ＋ of the polyanions. Irradiated with UV light, the transparent films changed from colorless to blue and returned to original color when it was exposed in air. The photochromic efficiency during the coloration process and the velocity during the bleaching process were enhanced with increasing of polyoxometalates content, which indicated that the PWA content effected on the photochromic properties of the PWA/PVPd composite thin films.