【作者】 徐冰冰；

【导师】 许林；

【作者基本信息】 东北师范大学 ， 无机化学， 2009， 博士

【摘要】 变色材料的种类十分丰富,由于多金属氧酸盐在变色领域展示出广阔的发展前景,从而受到了越来越多的关注。本论文工作以多金属氧酸盐为电致变色活性组分通过交替沉积自组装技术与溶胶-凝胶技术制备变色材料。利用交替沉积自组装技术,将Dawson型钨磷酸和聚乙烯醇组装到膜中,得到了具有既可光致变色又可电致变色的双模式变色复合膜。这种双模式变色复合膜无论是在紫外光激发还是在电激发下都能产生由无色变为蓝色的现象,而且着色后的薄膜在可见光照射下,或是通过施加正电压,均可以使其褪色。复合膜的着色和褪色过程可重复多次,而几乎没有吸光度的损失。通过FT-IR谱和X-射线光电子能谱等测试手段研究复合膜的组成和结构。采用紫外-可见光谱分析该复合膜的光致变色性质。采用光谱电化学方法考察薄膜电致变色性质。通过原子力显微镜手段表征复合膜的表面形貌。采用交替沉积自组装方法,制备了含有多金属氧酸盐阴离子（P2W18）与聚紫精阳离子（PXV）的电致变色复合膜。该复合膜能产生从无色到蓝色到蓝紫色的多颜色电致变色效果,即实现了宽幅的可调变光学吸收功能。循环伏安和光谱电化学表明,这两种材料复合到膜中后,均保留了各自的电致变色特点,而且都对电致变色光反差产生贡献。此外,该复合膜修饰电极在pH=1-5.5的范围内十分稳定,其氧化还原峰位置与溶液pH呈线性关系,说明该复合膜还具有pH传感性质。基于考虑“构效关系”的分子设计思想,系统的考察了膜结构对含有多金属氧酸盐（P2W18）和聚电解质（PAH）薄膜的电致变色性质的影响。经过光谱电化学和原子力显微镜等研究显示,组分的浓度和氯化钠的浓度,对复合膜的结构产生了巨大的影响。采用较高的多金属氧酸盐和聚电解质的浓度或者聚电解质中含有较高氯化钠的浓度制备出的薄膜,具有较厚的和较紧密的膜结构。这样的结构能增加多金属氧酸盐在薄膜中的吸附量所以提高了薄膜的电致变色光反差;但是由于紧密的结构阻碍了离子在膜中的传递,因而降低了电致变色的响应速度。因此,可以通过调控复合膜的制备过程,力求实现在分子水平上调节复合膜的电致变色性质。使用溶胶-凝胶方法,制备了一种含有十二钼磷酸的气致变色硅胶传感材料。该气致变色材料的制作过程非常简单,而且这种负载了多酸的硅胶材料能够在室温下检测一些具有还原性的气体（例如:H₂S和SO₂）而无需任何能量消耗。这种钼磷酸-硅胶材料在与H₂S气体接触后,其颜色由黄色迅速变为深绿色,该气致变色反应复合一级反应动力学。与SO₂气体相比较,该材料对H₂S气体具有更强的敏感度,这是由于H₂S气体的还原性更强导致的。更多还原

【Abstract】 Chromogenic materials have attracted much attention due to the applications in large area glazing, information displays, switch devices and optical storage. In this paper, we focus on the preparation of chromogenic materials based on polyoxometalates by layer-by-layer assembly and sol-gel technology.We successfully prepared PVA–POM multilayer films with concurrent photochromism and electrochromism by layer-by-layer self-assembly technique. The composite films can be photochromic and electrochromic from transparent to deep blue by either irradiation with UV light or electrochemical induce, and the photochromism and electrochromism is reversible. The layered nanocomposite films were studied by UV–vis absorption, cyclic voltammetry, chronoamperometry, X-ray photoelectron spectra and atomic force microscopy.We present our exploration in the development of a“dual electrochrome”composite film fabricated from the tungstophosphate （P2W18） and poly（hexyl viologen） （PXV） by a layer-by-layer self-assembly method. The polyanion and polycation species in the multilayer film are both cathodically coloring electrochromic material. The resulting“dual electrochrome”film could display color changes from colorless to blue to violet, achieving a breadth of gray-scale control with adjustable absorption. The high contrast, extended color range, suitable response time, and low operation potential of the electrochromic film should be promising to meet the requirement for developing flexible displays and electrochromic devices. Furthermore, the P2W18/PXV multilayer film modified ITO electrode is pH sensitive, showing a promising multifunctional application.We investigated the effects of film structure on the electrochromic performance of LbL films assembled from inorganic nanoparticle tungstophosphate （P2W18） and weak polyelectrolyte poly（allylamine hydrochloride） （PAH）. The influences of film structure on the electrochromic properties of the multilayer were investigated through varying fabrication conditions. Spectroelectrochemical and electrochromic characterizations of assembled films reveal that high concentration of polycation, anion and salt produces thicker and denser film structure, leading to high optical contrast and color efficiency whereas slow response times. Among the three parameters discussed above, salt concentration has the strongest influence on the electrochromic multilayer structure. By adjusting multilayer structure properly, dramatic changes of the optical contrast and response time can be realized.We report the preparation and characterization of a gasochromic silica sensing material containing POM. The fabrication procedure of the gasochromic monolithic pieces is very simple. In addition, the advantage of the POM-SiO2 material is that it is capable of detecting some reducing gases （H₂S and SO₂） at room temperature without any power consumption. The gasochromic material exhibits higher sensitivity to H₂S than to SO₂. The gasochromic response is strongly correlated to the reducing ability of the gas.更多还原