硫化镉纳米粒子分级自组装的机理研究

发布时间：2018-04-10 22:40

本文选题：CdS纳米粒子 + 分级自组装　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：纳米材料因为其具有独特的结构和优良的性能逐渐受到人们的重视。近三十年来发展非常迅速,各种不同的形貌、尺寸、功能以及性质的纳米材料逐渐被科研工作者开发出来。设计不同形貌的纳米材料是人们一直热衷的研究方向,而对引起纳米粒子产生不同形貌的原因的探讨——即纳米粒子间的相互作用力的研究则是对合成不同形貌的和不同性质的纳米粒子有着重大的研究意义。生物分子的分级自组装在自然界中十分广泛,其对于生命有机体是非常必要的。不仅仅是生物分子,无机纳米粒子与生物分子一样,也可以通过分级自组装的方式合成出各种有序的图案,并且整个过程表现为无特征的分级情况。之前人们所运用无机纳米粒子进行分级自组装的例子均是利用配体的作用,而不通过配体的作用使无机纳米粒子达到分级自组装的情况在之前的研究中鲜有提到。本文中我们展示了Cd S纳米粒子可以自发的实现分级自组装而获得各向异性的结构,整个过程具体为:自组装第一步包括聚集现有的小的Cd S纳米粒子(直径4 nm~6 nm)到大的超粒子中(直径为25 nm~30 nm)随后Cd S超粒子组装成几百纳米甚至几千纳米长的链和管。我们通过DLVO理论进行了证明:形成各向异性的一维Cd S结构是由于在构建模块中尺寸的增加而产生动力学稳定的超粒子,小的纳米粒子三维组装聚集成更大的超粒子,此过程则为热力学控制的过程;超粒子协助自身通过从热力学控制的自组装转换为动力学控制的自组装进一步进行一维组装形成各向异性的一维纳米链以及纳米管结构。在研究中发现,纳米粒子由于通过增加不同的能垒形成不同方向的连接。整个过程中伴随着粒子尺寸的增加存在着协同作用。具体为在尺寸较小的时候,粒子更易发生三维的组装。而随着组装的进行,粒子的半径增大,到一个临界点之后则更易发生一维的组装。这项研究对于理解复杂本质的无机纳米粒子的自组装提供了新的思路,并且在之前的研究中鲜有提到。本文提出了尺寸对协同作用的影响,以及显示了尺寸诱导协同作用可以认为是在各种无机纳米粒子中的分级自组装中普遍存在的特点。进一步推进了对纳米级相互作用的研究,对合成不同的形貌以及更优良的性质的纳米材料具有较大的指导意义。
[Abstract]:Nanomaterials have attracted more and more attention because of their unique structure and excellent properties.In the past three decades, various kinds of nanomaterials, such as morphology, size, function and properties, have been developed by researchers.The design of nanomaterials with different morphologies has always been a hot research direction.The study on the causes of different morphology of nanoparticles, that is, the interaction between nanoparticles, is of great significance in the synthesis of nanoparticles with different morphology and different properties.Hierarchical self-assembly of biomolecules is widely used in nature and is necessary for living organisms.Not only biomolecules, but also inorganic nanoparticles, like biomolecules, can synthesize various kinds of ordered patterns by hierarchical self-assembly, and the whole process is characterized by non-characteristic fractionation.Previous examples of using inorganic nanoparticles for staged self-assembly have been based on the use of ligands, but it has not been mentioned in previous studies that inorganic nanoparticles can achieve fractionated self-assembly without the action of ligands.In this paper, we show that CDs nanoparticles can spontaneously achieve hierarchical self-assembly to obtain anisotropic structures.The whole process is as follows: the first step of self-assembly consists of aggregating the existing small CDs nanoparticles (4 nm~6 nm in diameter) to large superparticles (25 nm~30 nm in diameter) and then assembling the CDs superparticles into hundreds of nanometers or even thousands of nanometers long chains and tubes.It is proved by DLVO theory that the formation of anisotropic one-dimensional CD S structure is due to the increase in the size of the building module to produce dynamic stable superparticles, and the smaller nanoparticles are assembled into larger superparticles in three-dimensional assembly.This process is thermodynamically controlled, and the superparticle helps to form anisotropic one-dimensional nanochains and nanotube structures by transforming itself from thermodynamically controlled self-assembly to kinetic self-assembly.It is found that nanoparticles are connected in different directions by increasing different energy barriers.There is a synergistic effect in the whole process with the increase of particle size.Specifically, when the size is small, particles are more likely to occur three-dimensional assembly.However, the radius of the particles increases with the assembly, and it is easier to assemble one-dimensional particles at a critical point.This research provides a new way to understand the complex nature of inorganic nanoparticles self-assembly, and has not been mentioned in previous studies.In this paper, the effect of size on synergism is presented, and it is shown that size induced synergy can be considered to be a common feature in hierarchical self-assembly of various inorganic nanoparticles.The study of nanoscale interaction is further promoted, which is of great significance for the synthesis of nanomaterials with different morphologies and better properties.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O614.242;TB383.1

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