嵌段共聚物（PS-b-PAA）/无机杂化材料的研究和应用

【作者】 胡冰；

【导师】 雷忠利；

【作者基本信息】 陕西师范大学 ， 材料物理与化学， 2008， 硕士

【摘要】 随着科学的不断发展,材料科学从单一的聚合物材料正在向和各学科交叉转变,其中有机-无机杂化材料已成为材料科学发展的重要方向之一。有机-无机杂化材料因在光学透明性、可调折光指数、高催化活性、耐高温及耐磨损等方面表现出优良的性能而广泛应用于新型的结构材料、涂层材料、光学材料、电学材料、磁学材料和生物学材料等方面,使用越来越广泛。因此,寻求具有多种优异性能的该类新材料将是今后一个时期材料领域的重点研究课题之一。基于以上想法,本论文在简述了近年来有机-无机杂化材料研究进展的基础上,主要开展了以下三方面的工作:1.以嵌段共聚物PS-b-PAA为稳定剂,在超声辐照下成功地制备了分散性较好、尺寸较均匀的立方相纳米银颗粒。用原子力显微镜（AFM）、红外光谱（FT-IR）、透射电镜（TEM）、紫外-可见吸收光谱（UV-Vis）和热分析（TGA）等对制备的纳米银复合材料进行了表征。红外结果表明超声辐照并没有破坏聚合物的链结构。聚合物的引入,对纳米银颗粒起到了很好的分散保护作用。低浓度的硝酸银溶液,得到粒径较小的纳米银颗粒;随着硝酸银浓度增大,纳米银颗粒粒径也增大;而聚合物的浓度增大时,所得银纳米颗粒粒径减小。聚合物的重均分子量越大,银纳米颗粒的粒径越小。TG结果说明银纳米粒子的引入,能提高聚合物的热稳定性。2.利用低强度超声辐照技术在室温下用嵌段共聚物作为保护剂,制备出单晶的银纳米棒和高度有序的树枝状超分子银纳米材料。电子衍射图表明生成的银纳米棒为单晶。银纳米晶的形态从棒状的银纳米晶生长为树枝状的银纳米晶。溶液中AgNO₃的浓度对树枝状银的形成有生长起非常重要的作用。封盖高分子材料的浓度与银浓度的比率同样对银纳米结构的形状及大小有影响。这些不同的银纳米材料与纳米结构可能在催化中有重要的应用。这种方法可以扩展到制备其它贵金属的新型纳米结构。3.通过逐层自组装（Layer-by-Layer）的方法将磁性粒子吸附到双亲嵌段共聚物表面,制备了双亲PS-b-PAA/Fe₃O₄复合材料,并以该复合材料作为载体固定化果胶酶。讨论了自由酶和固定化酶的贮存稳定性,可重复利用性和动力学性质。结果表明:固定化酶相对自由酶最显著的优点是可以长期贮存。且固定化酶有很好的pH稳定性,能够在很宽的pH范围内保持很高的酶催化活性。可具有良好稳定性的固定化酶使得利用昂贵的酶的成本降低并在生物催化技术方面开辟了新的领域。而且由于PS-b-PAA/Fe₃O₄粒子表面吸附的Fe₃O₄增强了其磁力性能,使得其在反复利用的催化过程中具有简便、快速分离的优点。更多还原

【Abstract】 With the continuous development of science, Materials science from single polymer material changes to the interdisciplinary, organic-inorganic hybrid materials of scientific development has become one of the important directions. The inorganic-organic hybrid materials are used widely in electricity, magnetics, and optics fields and so on, because of its interesting optical, magnetic, catalytic and thermal steady properties. Therefore, to seek such new materials of excellent performance will be one of the key research subjects in the coming period on the field of materials subject. In this thesis, our research is mainly focused on the following three parts:1. Silver nanoparticles were synthesized by using amphiphilic block copolymer PS-b-PAA based on the flexibility of the copolymer chains and the complex effect of -COOH in the poly（crylic acid） with Ag⁺ and Ag under ultrasonic irradiation. The product was characterized by Atomic Force Microscopy （AFM）, Fourier Transfer Infrared Spectrometer （FT-IR）, Transmission Electron Microscope （TEM）, UV-Vis spectrum and Thermal Gravity Analysis （TGA）. The FT-IR results revealed that the backbone of the PS-b-PAA block copolymer was not be cleavage during the synthesis of the silver nanoparticles under ultrasonic irradiation. The TEM results revealed that the size of the resulting silver nanoparticles prepared basing on the copolymer was strongly dependent on the initial concentration of the silver ion solution and the copolymer. Low initial silver ion concentration allowed for yielding silver nanoparticles with a small size and the size of the silver nanoparticles increased with the concentration of the silver ion solution increasing. And that the silver nanoparticles decreased with the M_n of the copolymer increasing.2. Using the block copolymers as a protective agent, the single crystals of silver nanorods and highly ordered dendritic supramolecular silver nanomaterials were prepared under low-intensity ultrasound irradiation at room temperature. The electronic diffraction pattern indicated that the silver nanorods are single crystal. The shape of the silver nanocrystal grows from stick to dendritic. The concentration of silver nitrate and copolymer play an important role in formation and growth process of the silver nanocrystal. These different silver nanomaterials possibly have important application in catalysis applications. This method can be extended to prepare the new type of nano-structure of other precious metals.3. The idea of preparing the surface of Fe₃O₄ layer pre-adsorbed on the copolymer via layer by layer self-assembly approach receives special relevance in enzyme technology. The copolymer PS-b-PAA/Fe₃O₄ support presents a very simple, mild, and time-saving process for enzyme immobilization. We discussed the storing stability, reusability and kinetic property of the free enzyme and the Immobilized enzyme. The most significant advantages of the Immobilized enzyme is the long-term storing stability. And immobilized enzymes have good pH stability in a wide pH range, maintaining a high level of enzyme activity. The immobilized enzyme which have good stability reduced the cost of the expensive enzyme and opened up a new field of the catalytic technology. These particles, premodified with the layer of magnetic nanoparticles to impart a magnetic property were repeatedly used as catalysts following their rapid and easy separation with a magnet.更多还原