【作者】 张良苗；

【导师】 陆文聪；

【作者基本信息】 上海大学 ， 材料学， 2009， 博士

【摘要】 纳米材料因为它们所具有的独特的磁学、电学、光学性质,一直是科学家研究的热点。目前研究的难点是如何合理的控制材料的定向生长,进而实现对其尺寸、维度、组成、晶体结构乃至物性的调控,深入研究结构与物性的关联、并最终实现按照人们的意愿设计合成功能材料。本论文总结了纳米材料的结构、制备、形成机理和性质等方面的进展,把液相合成方法拓展到新颖、特殊结构的设计合成与生长,在研究形成机制及所获得新型纳米结构的物性等方面进行了有益的探索;并在纳米氧化铝粉体、薄膜的廉价制备以及所设计路线工业化生产的可能性方面进行了大胆的尝试。论文中取得了一批创新性成果,主要内容概括如下:1.建立了纳米Al₂O₃空心球的乳液界面控制合成新技术,通过对实验过程中影响空心球形成的各种因素进行考察,阐述了其形成机理。表面活性剂的加入量是反应中最重要的影响因素,它影响乳液中水核的存在形状,最终影响产物的形貌。通过增加表面活性剂Span80的量至1.5g,使之形成带状水核,成功合成了竹叶状Cu（OH）2单晶。通过煅烧得到了表面具有纳米孔的CuO纳米带。并对其带状结构的光学性质进行了初步研究,为进一步探索该类独特结构的优异物理化学性质奠定了坚实的基础。2.利用柠檬酸根可以和很多金属离子络合而控制水解速率及产物结晶方向的特点,在醇-水混合溶剂作用下合成出纳米AlOOH的核壳结构。高倍透射电镜照片显示:其二级结构是由纳米薄片以及其卷曲而成的纳米管组成。核壳结构的形成可归因为酸性条件下表面晶核溶解-再沉淀的过程,不同反应时间产物的透射电镜阐述了这一机制。由于其具有大的比表面积、均一的孔径分布,在吸附与分离、催化等领域将展示良好的应用前景。初步研究表明其在室温条件下显示出较强的对刚果红染料的吸附性能。3.发展了溶剂热法,选择丙酮-水作混合溶剂,调控合成了AlOOH的空心球。通过SEM,TEM,XRD,BET和PL等手段对产物的结构和形貌进行了表征。深入研究了实验参数对产物形貌的影响,探讨了AlOOH的三维结构的形貌与发光性能之间的关系。通过这些新型纳米结构的合成,发展了一条简单有效的制备金属氧化物核壳及空心球纳米结构的途径,并为新的合成方法学的建立奠定了基础。4.建立了以废铝料为原料制备高纯度纳米氧化铝的新流程。废铝料经过与硫酸氢铵反应,利用重结晶技术,实现了硫酸铝铵的纯化。硫酸铝铵与碳酸氢铵等反应得到了碳酸铝铵,经过煅烧最终得到了纯度可达99.99%粒径分布集中在49nm的α-Al₂O₃。并对中间产物碳酸铝铵的合成过程进行实验设计,利用支持向量机方法处理实验数据,得到了控制收率的优化区间。本流程既处理了废料,又为纳米氧化铝的工业化生产找到了一条廉价的工艺路线。5.建立了从废料中提取的无机盐出发,采用溶胶-凝胶法制备氧化铝纳滤膜的方法。深入研究了影响薄膜开裂的各种影响因素（例如支撑体的孔径大小,氧化铝含量,干燥控制剂的选择和用量,浸渍时间,干燥和煅烧条件等）,制得了表面无开裂、无针孔缺陷的不对称膜。并应用数据挖掘方法处理实验数据,得到了不开裂膜制备条件的半经验方程式。更多还原

【Abstract】 Nanomaterials have drawn continuous research attention because of their unique electrical, optical and magnetic properties different from that of bulk materials. But the main challenge in this area is how to precisely control the sizes, dimensionalities, compositions and crystal structures in nanoscale, which may serve as a powerful tool for the tailoring of physical/chemical properties of materials in a controllable way. In this dissertation, based on the comprehensive and thorough investigation of a lot of literatures, I gave a concise review on the structures, properties, applications and preparation methods. Following that, solution-based routes were developed to realize the chemical synthesis of special and novel nanomaterials. Furthermore, valuable explorations have been carried out on the research on their growth mechanism and properties and attempts have been made on low-cost preparation of alumina nanopowders and the possibilities of large scale production. The research conclusions provide some original and innovative results, and the main points are summarized as follows:1. A new and feasible emulsion route was established to control the synthesis of Al₂O₃ hollow spheres. The reaction was accomplished at the organic/aqueous biphasic boundary. Based on a series of comparative experiments under different reaction conditions, the probable formation mechanism of Al₂O₃ hollow spheres was proposed to be emulsion-morphology controlled growth process. The Al₂O₃ hollow spheres could be tailored by using different concentration of surfactant. In addition, Cu（OH）2 bamboo-leaf-like single crystals were successfully synthesized by increasing the surfactant amounts to 1.5g. It could be converted to a porous structure （CuO） after removing the Span80 molecules via calcination. The optical properties of these CuO nanostructures were studied with UV-vis spectra measurements and found to exhibit blue shifts in UV-vis spectra and possess larger band gaps compared with those of bulk crystals. 2. The AlOOH core/shell microspheres were successfully synthesized in large-scale via a one-step template-free solvothermal route. Most shells of the spheres composed of loosely stacked nanoplatelets and nanotubes as second order structure. Based on the evolution process of the products at various stages of the reaction, a possible mechanism was proposed to the formation of core-shell structures, which involved a surface reaction-dissolution-recrystallization process. Citrtate anion, as a coordination agent and shape modifier, plays a key role in determining the morphology of the final products. The as-prepared AlOOH core-shell superstructures are powerful in the removal of Congo red pollutant from waste water. Taking into account the high BET surface area and excellent porous properties, this novel structure is expected to be useful in many other applications, such as catalysts, sorbents, ceramics, and optical nanodevices.3. A solvothermal method using the mixed solvent of water and acetone was developed to prepare AlOOH hollow spheres. The structure and morphology of the products were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, field emission scanning electron microscopy （FE-SEM）, Brunauer-Emmett-Teller （BET） and room-temperature photoluminescence （PL） spectra, etc. The effect of the important experiment parameters on the morphology of the final products was deeply investigated. And we also investigated the dependent relationship between morphologies and PL. And this work may provide new insights into preparing other inorganic core/shell spheres with complicated structure.4. A new synthetic strategy has been established to prepare nano-alumina of high purity with exhausted aluminum scraps as the raw material. Aluminium ammonium sulphate （AA） with high purity was obtained via the reaction of aluminum scrap reacted with ammonium bisulfate and recrystallization several times. And aluminium ammonium carbonate hydroxide （AACH） was synthesized via the reaction of AA reacted with ammonium bicarbonate. The precursor was calcined to getα-Al₂O₃ nanometer powders with average grain size of 49nm. Inductive Coupled Plasma Emission Spectrometer （ICP） analysis result shows that the purity of Al₂O₃ is beyond 99.99%. Support vector machine, a new computational method which can avoid over-fitting and has powerful prediction ability, has been used for optimizing process parameters of AACH and establishing the models between process parameters and the mass ratio of AACH. By this way, the costs of the preparation of nanometer alumina can be reduced while the industrial waste is disposed at the same time.5. Alumina nanofiltration membrane has been prepared by sol-gel dip-coating method. The effects of preparation parameters during the preparation process on the quality of the final membrane were studied. These parameters included pore size of the substrate, alumina content, selection and dosage of the drying control chemical additives, times of dipping, drying process and heating conditions of the gel membrane. The problem of the desquamation between the selective layer and the substrate was solved; large area membrane without pinholes and cracks was prepared successfully. Orthogonality experiments were designed to examine the effects of different preparation parameters. Semi-empirical mathematical model of preparing crack free membrane was built based on the data mining of the preparation data.更多还原