基于小角中子散射的桥连接胶体系统理论与实验研究

发布时间：2018-03-28 10:16

本文选题：胶体系统　切入点：桥连接模型　出处：《清华大学》2016年博士论文

【摘要】：胶体系统在日常生活及工业应用中广泛存在,对胶体粒子间作用机制的研究对于胶体系统性能的优化具有重要意义。在桥连接作用下,胶体系统会出现单相-多相-单相这一奇特的相变过程,尽管已有的研究已经提出了桥连接作用这一假设,但是并未对其进行验证。小角中子散射技术可有效研究纳米到微米尺度材料的结构,因此常常用于胶体系统的结构研究。本文基于小角散射理论,建立了桥连接模型,并对胶体系统的相图信息进行了理论及实验研究。主要内容如下:(1)在小角散射理论框架下,利用多组分粘性硬球模型构建桥连接模型,对系统关键参数进行了解析求解,包括其结构因子、散射强度理论曲线以及相图中的旋节线、最大桥连接吸引力和等效硬球作用点;(2)建立了桥连接作用下双组分粘性硬球系统到单组分系统的映射模型,使单组分粘性硬球系统的研究成果,如逾渗线与双节线的结论可直接应用于桥连接系统;(3)研究桥连接作用下特定实验系统(PS和PNIPAM混合系统)的理论相图并与实验观测结果对比,验证了该模型的有效性;(4)利用桥连接模型,研究组分相对大小和组分间粘性参数对系统相图的影响,还研究了大组分粒子间等效作用力的结构特征。数值拟合结果可为实验操作提供指导;(5)通过小角中子散射实验研究牛血清蛋白(BSA)和氯化钇(YCl3)混合系统,并利用桥连接模型进行数据分析,研究了不同Y3+浓度下系统的散射曲线以及BSA蛋白分子组成和形状的变化情况。本论文证明了双组分胶体系统中桥连接作用的存在,为实验系统中单相-双相-单相的相变过程提供了更深层次的物理解释。本论文建立的桥连接系统到单组分粘性硬球系统的映射模型,使许多已有的单组分粘性硬球系统的研究成果可以直接应用于桥连接系统,极大简化了桥连接系统的研究难度。同时,本文首次利用桥连接模型和小角中子散射技术研究复杂胶体系统,为小角散射领域的实验物理学家们提供了一种新的行之有效的研究方法,也为类似系统的研究提供了理论和实验支撑。
[Abstract]:Colloidal system is widely used in daily life and industry. The study on the mechanism of colloidal particle interaction is of great significance to the optimization of colloidal system performance. The colloidal system has a peculiar phase transition process of single-phase to polyphase, although the hypothesis of bridging interaction has been proposed in previous studies. However, it has not been verified. The small-angle neutron scattering technique can effectively study the structure of nanometer-to-micron scale materials, so it is often used to study the structure of colloidal systems. Based on the theory of small-angle scattering, a bridge connection model is established in this paper. The phase diagram information of the colloidal system is studied theoretically and experimentally. The main contents are as follows: (1) in the framework of small angle scattering theory, the bridge connection model is constructed by using the multi-component viscous hard sphere model, and the key parameters of the system are solved analytically. Including its structure factor, theoretical curve of scattering intensity, spin nodal line in phase diagram, maximum bridge connection attraction and equivalent hard sphere action point, the mapping model of two-component viscous hard sphere system to one-component system under bridge connection is established. The results of single-component viscous hard sphere system, such as the conclusion of percolation line and double nodal line can be directly applied to bridge connection system, are used to study the theoretical phase diagram of a specific experimental system under bridge connection and the mixed system of PS and PNIPAM), and the results are compared with the experimental results. The validity of the model is verified. (4) the influence of the relative size of the study group and the viscosity parameters between components on the phase diagram of the system is verified by using the bridge connection model. The structural characteristics of the equivalent force between large component particles were also studied. The numerical fitting results can provide guidance for the operation of the experiment. The mixed system of bovine serum protein (BSA) and yttrium chloride yttrium chloride (YCL _ 3) is studied by small angle neutron scattering experiment. The scattering curves of the system and the changes of the molecular composition and shape of BSA protein under different concentrations of Y _ 3 were studied by using the bridge connection model. The existence of bridging interaction in the two-component colloid system was proved in this paper. It provides a deeper physical explanation for the phase transition process of single-phase, two-phase and single-phase in the experimental system. In this paper, the mapping model from bridge connection system to single-component viscous hard sphere system is established. Many existing research results of single-component viscous hard ball system can be directly applied to bridge connection system, which greatly simplifies the research difficulty of bridge connection system. At the same time, In this paper, the bridge-connected model and small-angle neutron scattering technique are used to study the complex colloidal system for the first time, which provides a new and effective method for the experimental physicists in the field of small-angle scattering. It also provides theoretical and experimental support for the research of similar systems.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O571.5

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