【作者】 任媛；

【导师】 武利民； 陈敏；

【作者基本信息】 复旦大学 ， 材料学， 2011， 硕士

【摘要】 目前,无机纳米材料因其具有优良的性质成为材料领域的研究热点。纳米粒子是一种介于宏观固体和分子间亚稳态的中间态物质。当粒子尺寸进入纳米数量级(1—100 nm)时,由于纳米粒子的表面组成基元占较大比例,使得其显示出强烈的体积效应、量子效应、表面效应和量子隧道效应。同时纳米材料的电学、光学、磁学等特殊性质,给材料的应用注入了新的活力。本论文主要研究了铃铛型二氧化钛(WiO2)复合微球和上转换稀土纳米颗粒薄膜的制备及其性能研究：(1)采用层层自组装技术,在商品级TiO2纳米粒子(P25)的表面交替组装PSS(聚苯磺酸钠)/PDDA(聚二烯丙基二甲基氯化铵)聚电解质后,进一步通过溶胶-凝胶法,在聚电解质表面包覆二氧化硅(SiO2)壳层,得到TiO2/PSS/PDDA/SiO2复合微球。在紫外光的照射下,聚电解质层被P25降解除去,得到具有铃铛结构的WiO2@j@SiO2纳米粒子。TEM观察显示,复合微球的核(TiO2)和壳层(SiO2)的空隙为2-12nm,可由聚电解质的层数来控制。将该复合微球掺杂到水性聚氨酯中,可得到紫外屏蔽性能优异的耐老化透明涂层。对罗丹明B溶液的降解实验结果表明,核和壳层之间的空隙越大,复合微球的光催化活性越大。(2)采用溶剂热的方法制备了形态规整、荧光性能优异的上转换稀土纳米晶粒NaYF4:Yb, Er。随后,借助超声搅拌将稀土纳米晶粒分散在氯仿中得到稀土纳米晶粒的油性分散液。在分散液中加入少量的水,形成平整的油/水界面。最后,向油/水界面逐步滴加无水乙醇。在自由能降低的驱动下,分散在有机溶剂中的稀土纳米晶粒逐渐迁移到油/水界面,形成规整的单层颗粒薄膜。SEM观察显示,制备的单层薄膜具有规整的形貌。重复同样的实验步骤可制备多层纳米颗粒薄膜。薄膜的荧光性能与薄膜的层数成正比。本方法过程简单易行,可以用于显示器或者传感器等薄膜材料的制备。更多还原

【Abstract】 In recent years, inorganic nanomaterials are becoming the hotspot in academic research because of their excellent properties. Nanoparticles are intermediate materials between bulk materials and molecules. For the nanoparticles with size less than 100 nm, the proportion of atoms on the surface of particle is extremely high. As a result, volume effect, quantum effect, surface effect and quantum tunneling effect are the basic properties of nanomaterials. Moreover, some other functional properties, such as electric property, luminescence property and magnetic property have extended the application of nanomaterials.In this paper, rattle-type TiO2@SiO2 nanoparticles and monolayer films of upconversion rare earth nanoparticles NaYF4:Yb,Er were prepared. Also the properties of the nanomaterials were investigated. All the research contents and results are shown as follows:(1) Rattle-type TiO2@SiO2 particles, with commercial TiO2 particles encapsulated into hollow SiO2 shell, were fabricated by successive coating of multilayer polyelectrolytes and SiO2 shell onto TiO2 particles and then treatment by UV irradiation to remove the polyelectrolyte layers. TEM observation showed that the composite particles had a unique rattle-type structure in which there was void space between the TiO2 core and SiO2 shell. The photocatalytic degradation of Rhodamine B indicated that these composite particles with larger void space tended to have higher photoactivity. The polyurethane films doped with rattle-type TiO2@void@SiO2 composite particles had very good UV-shielding property.(2) Upconversion rare earth nanoparticles NaYF4:Yb,Er with uniform morphology and excellent luminescence property were prepared by solvothermal method. And then, the nanoparticles were dispersed into chloroform by magnetic stirring. Water was added to the vessel to produce a chloroform/water interface. And then some ethanol was added to the interface at a low rate. At the same time, the rare earth nanoparticles were trapped at the interface gradually to form a monolayer film. Repeating the same strategy, the nanoparticles were also successfully self-assembled into multilayer films. The luminescence intensity was in direct proportion to the number of the layers. The procedure is very simple and effective. These films hold immense promise for a number of technical applications in areas such as display and sensing materials.更多还原