多金属氧酸盐纳米复合膜的制备、表征与光致发光/变色性质研究

【作者】 张宏宇；

【导师】 王恩波； 许林；

【作者基本信息】 东北师范大学 ， 无机化学， 2002， 硕士

【摘要】 二十一世纪的“光子时代”即将到来! 近十年来，纳米科学、材料科学、微电子科学以及超分子科学等学科的不断交叉发展和积累，为新型无机-有机发光，光电变色材料提供了坚实的理论准备。功能性薄膜材料在材料科学领域中起着举足轻重的作用。这些有序的分子膜主要是通过LB技术，自组装技术和聚电解质交替沉积技术来组装实现的。它们在纳米材料，传感器，光学器件等领域有广泛的应用前景。 多金属氧酸盐（POMs）是一类有确定结构，且具有多种功能特性的金属氧簇化合物。它们作为构建功能材料“万能”的无机建筑块吸引了广泛的关注，现已经成为国际上的研究热点。若将功能性的多金属氧酸盐应用到薄膜领域中，这将极大拓宽材料科学的研究领域，具有现实意义。基于以上观点，作者对含有多金属氧酸盐的发光和光致变色薄膜进行了研究，并取得了一些有益的成果。具体结果如下： 1．用Layer-by-Layer静电自组装的方法成功的构建了一系列具有荧光性质的多层膜，{PEI/PSS/PAH/（POM/PAH）_n} (POM=[Eu(BW₁₁O₃₉)₂]^15-，[Eu(SiW₁₁O₃₉)₂]^13-，[EuP₅W₃₀O₁₁₀]^12-)。用紫外光谱仪跟踪了多层膜的制备过程，发现吸收值随沉积层数的增加而线形增加。着说明了多层膜的沉积过程是一个均一过程。多层膜的X-ray光电子能谱不但证明了POM和PAH在膜中的存在，而且还给出了多层膜的增长性，与紫外光谱所得结果一致。原子力显微镜（AFM）图象表明多层膜表面较均匀，且覆盖率较高。说明用LbL的方法可以制备高质量的多层薄膜。薄膜的XRR谱未能给出令人满意的Kiessig边纹，因此无法获得准确的膜厚度和粗糙度。经过可靠的估算，多层膜的厚度在纳米尺度范围内。薄膜在室温下的荧光光谱显示出稀土离子Eu³⁺的5^D₀→⁷F_J的特征谱线，其发光行为与POM-Eu的固体样品相同。 2．用浸渍法制备了一种新型的光致变色复合膜EuP₅W₃₀/PVP，其发光行为也得到了研究。SEM图象给出了复合膜的表面形貌。观察到多金属氧酸盐簇与包裹在外层的PVP形成球状的粒子。膜的红外光谱证实了无机、有机物种间的相互作用，但EuPSW3。的几何构型在复合物中保持不变。复合物体现明显的三步失重，基于失重百分数得膜的实验式为WPh2厌uPSW30)田ZO)102。复合物的光致变色行为用紫外光验证。经紫外光照射后复合膜在可见区的吸收强度强烈增强。在氧气的存在下，复合膜表现出可逆的变色行为。顺磁共振（ESR）证实了其变色机理，是由于生成了还原物种的杂多蓝，而使复合膜具有变色行为。此外，复合膜的荧光光谱也得到了研究。其体现了Ef”的’D。一h的特征发射谱线。更多还原

【Abstract】 The ’photon era’ of the 21st century is coming, and already!In the last decade, nanometer science, material science, microelectronics and supramolecular science have been rapidly developed, so they can provide essential prerequisite for the study of novel inorganic-organic photoluminicent and photochromic materials. It is a fact that functional film materials play a great role in material science. Organized molecular film, fabricated mainly by Langmuir-Blodgett method, self-assembling technique and polyelectolytes alternating deposition technique, have various potential applications hi the fields of nano-materials, sensors, optical devices, ect.Polyoxometalates (POMs), a class of molecularly defined inorganic metal-oxide clusters, posses intriguing structures and diverse properties and, therefore, attract increasing attention worldwide. For this, it will be of critical importance to successfully incorporate the functional properties of POMs into the ultrathin material. In this thesis, author carried out a series of research hi photoluminicent and photochromic film based on POMs, and some constructive and helpful results were obtained. All the results are summarized as follows:1. A series of photoluminecent multilayer films, (PEI/PSS/PAH/ (POM/PAH)n} (POM = [Eu(BWn039)2]15~ , [Eu(SiWn 039)2]13" . [EuPsWaoOno]12") ?were successfully fabricated by electrostatic layer-by-layer assembly. UV-vis spectroscopy was used to follow the absorbance with increasing the number of bilayer indicates a process of uniform assembling. The XPS measurements not only confirmed the presentation of POMs and PAH in multilayer films, but also showed that the peak intensities of the W4f and Njs levels increase as the number of (POM/PAH) bilayers increases, in agreement with result from the UV-vis spectra. The AFM images of the POM/PAH film show that the surface ofthe film is homogeneous and the coverage is high. The roughness of the surface of the film was calculated to be less 0.8 nm. It is regret that the satisfactory Kiessig fringes appearing in the X-ray diffraction pattern of a multilayer film was not obtained, and the thickness and roughness of film was not calculated accurately, either. The photoluminescent behavior of the multilayer film at room temperature was investigated to show the characteristic Eu3+emission pattern of 5Do~*7Fj. The fluorescence behavior of the multilayer is essentially identical to that of solid samples.2. A novel hybrid photochromic composite film composed of Preysslers heteropolyacid EuPsWso and PVP was prepared by dip-coating method. SEM was used to investigate the surface topography. The change of characteristic peak in the infrared spectra (IR) was investigated and it showed that the Preyssler geometry of EuPsWso was still preserved inside the hybrid film. The TG curve showed three steps of weight loss and approximately revealed the composition of the hybrid film, (VP)42(EuP5W3o)(H2O)io2. XPS, UV-vis and ESR were used to investigate the photochromic behavior and mechanism of hybrid film. From the above result, one can draw a conclusion that charge transfer took place between the organic and inorganic species under UV irradiation. Furthermore, the photoluminescent behavior of the multilayer film at room temperature was investigated to show the characteristic EuJ+emission pattern of 5Do-7Fj.更多还原