嵌段共聚物PEO-PPO-PEO在纳米金合成中的应用
文献类型：学位论文
| 作者 | 寿庆辉 |
| 学位类别 | 硕士 |
| 答辩日期 | 2011-06-09 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 郭晨 ; 刘会洲 |
| 关键词 | PEO-PPO-PEO 自组装 相互作用 贵金属金 纳米材料 |
| 其他题名 | Gold Nanoparticles Synthesis Using PEO-PPO-PEO Block Copolymer |
| 学位专业 | 环境工程 |
| 中文摘要 | 聚氧乙烯–聚氧丙烯–聚氧乙烯(PEO-PPO-PEO)嵌段共聚物（商品名Pluronic）在水溶液中可以自组装形成形貌和性质丰富的介观结构，具有生物相容、结构可控和温度敏感等优点，是制备纳米材料的理想元件。PEO-PPO-PEO嵌段共聚物用于贵金属纳米颗粒的合成，可以同时作为金属离子的还原剂、金属颗粒的稳定剂，实现了高稳定性的纳米颗粒的一步合成，合成步骤简单、经济且环境友好，具有很好的应用前景。论文结合各种光谱技术（紫外-可见光谱、红外光谱、拉曼光谱）和透射电子显微镜、暗场光学显微镜等形貌观察手段，研究PEO-PPO-PEO嵌段共聚物用于金纳米颗粒合成过程的影响因素，进一步调控合成各种结构的金纳米颗粒，同时探讨了纳米金合成过程中嵌段共聚物自身形态变化尤其是囊泡结构的形成。研究内容主要包括以下三个方面： (1) pH值对嵌段共聚物合成纳米金过程的影响应用Pluronic P123合成金纳米颗粒，在一定的反应物用量（P123, HAuCl4），只改变嵌段共聚物水溶液pH值的条件下，发现纳米金的形态、稳定性显著依赖于pH值的范围。在酸性条件下获得的纳米金稳定性较差，在碱性条件下嵌段共聚物吸附于纳米金颗粒表面形成核壳结构，稳定性高，能够适应一定范围内物理化学环境的改变。pH在11.12时，粒径在9.6 nm，均一性高。pH值影响Pluronic的醚氧键与金离子的结合能力以及Pluronic与金颗粒之间的疏水相互作用，进而影响金离子还原、金团簇的生长过程，与pH值在离子型表面活性剂合成纳米金的影响显著不同。 (2) 金团簇、核壳结构的制备研究在一定的pH值、反应物摩尔分量比的条件下，嵌段共聚物/金颗粒复合结构的形成。嵌段共聚物P123水溶液pH为11时，通过调节反应物体积比，制备了纳米金的团簇结构以及核壳结构的纳米金。固定反应物配比（VG:VP=0.1），在较低的碱性条件下（pH =8左右）能够合成粒径10 nm左右的金多面体，pH在10.57至11.63的范围内，获得嵌段共聚物包覆的核壳结构的纳米金。嵌段共聚物在一定形貌的金颗粒形成过程中不是简单的作为模板，而涉及嵌段共聚物Pluronic和金原子（包括金离子和金单质）的协同作用。 (3) 纳米金合成过程中嵌段共聚物Pluronic囊泡结构的形成应用硼氢化钠作为强还原剂，嵌段共聚物Pluronic作为稳定剂剂，在60℃下合成纳米金颗粒。纳米金颗粒粒径为5 nm，为典型的球体。同时，嵌段共聚物自组装形成囊泡结构，平均尺寸为66 nm，稳定性高。初步研究表明温度和金离子的加入对囊泡的形成起重要作用。 |
| 英文摘要 | Poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) block copolymers could self-assemble into several types of mesostructure with various morphologies and properties in selective solvents. The PEO-PPO-PEO block copolymers have many attractive advantages which makes them ideal building blocks of nanomaterials, e.g., temperature-responsivity, biocompatibility, and the self-assembled structures could be well controlled by varying the copolymer composition or adding additives. This thesis aims at controllable preparation of gold nanoparticles using PEO-PPO-PEO block copolymers, and investigating self-assembly behavior after the incorporation of gold compounds and gold nanoparticles formation. Through spectroscopic and microscopic obs- ervations, we investigate the mechanism of gold nanoparticles production using block copolymers. The main results are as follows: (1) Effect of pH on single-step synthesis of gold nanoparticles using PEO-PPO-PEO triblock copolymer in aqueous medium. Reactions are studied between variable pH value and fixed concentrations of the two reactants, HAuCl4 and P123 block copolymers. Results indicate that the reaction pathway during the nanoparticles formation can be controlled by varying pH value. The nanoparticles synthesized at pH=11.12 have an average diameter of 9.6 nm with a narrow size distribution, and the Pluronics are adsorbed on individual gold surface to form a core-shell structure via hydrophobic interaction. The present work provides an economic way to improve the dispersion and stabilization of the gold nanoparticles, and throws further light on the understanding of gold nanoparticles production using block copolymers. (2) One-Pot Synthesis of Plum Pudding Like Gold Clusters and Core/Shell Gold Nanoparticles Using Pluronic Block Copolymers Gold@polymer nanocomposites, including gold nanoparticle clusters and core/shell nanoparticles have been fabricated by tailoring the molar ratio of gold precursors to Pluronic P123 molecules. For gold clusters, the AuNPs are embedded in the Pluronic assemblies like plums in a plum pudding, and each one holds about 21 single gold nanoparticles. The core/shell nanostructures with AuNPs adsorbed by Pluronic molecules have an average diameter of 9.6 nm with a narrow size distribution. Gold polyhedras with a mean diameter of 12.8 nm could also be obtained by tailoring pH value of the P123 solution. The specific morphologies of the resultant nanocomposites were presumably obtained due to the synergistic interaction among several reactants. Gold nanoparticles with an average size of 5 nm were produced using NaBH4 as reductant in the Pluronic P123 aqueous solution at 60 °C. As the nanoparticles formed, a large population of vesicles was found for the first time. Vesicles have a mean diameter of 66 nm, according to TEM observation with the specimen negatively stained. The enhancement of hydrophobic interaction of PPO segment after the nanoparticles formation may promote the amphiphilic block copolymers to self-assemble into vesicles. (3) Polymersome formation from Pluronic block copolymers during gold nanoparticles synthesis. |
| 语种 | 中文 |
| 公开日期 | 2013-09-23 |
| 页码 | 77 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1664]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 寿庆辉. 嵌段共聚物PEO-PPO-PEO在纳米金合成中的应用[D]. 中国科学院研究生院. 2011. |
入库方式： OAI收割
来源：过程工程研究所
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