【作者】 孙海南；

【导师】 张长桥；

【作者基本信息】 山东大学 ， 化学工艺， 2011， 硕士

【摘要】 嵌段共聚物是由一系列不同的结构单元连接而成的大分子。由于不同种类单元之间不相容,因而嵌段之间相互排斥；又由于各结构单元之间是由化学键相互连接而成,因此会发生微相分离,在本体中和选择性溶剂中自组装形成有序形貌,如层状相、柱状相、球状相,以及更加复杂的自组装结构,如囊泡、复合胶束、环形胶束、多隔段胶束等。除了常见的柔性嵌段共聚物,一系列刚性以及刚柔嵌段共聚物被合成出来。研究表明,这些具有刚性嵌段的共聚物具有一些特殊的自组装行为,因此可以被应用于光学、微电子、膜工程等领域中。计算机模拟技术被广泛应用于研究化学问题,不但可以解释实验中观察到的现象,阐明微观机理,对实验起到辅助作用,而且也可以作为开展实验的指导。耗散粒子动力学方法作为一种粗粒化方法,由于其包含流体力学相互作用,体系动量守恒,柔性势使其积分步长可以比较大等优点,被广泛应用于嵌段共聚物自组装体系的研究中。在本论文中,我们应用耗散粒子动力学方法研究了具有一定刚性的两嵌段共聚物在选择性溶剂中的自组装行为。通过建立以粒子间的相互作用参数和溶液的浓度为变量的相图,考察了它们对各有序相位置和区域面积的影响。由于有序相的演化过程对于研究微观机理和指导实验有重大意义,我们还考察了层状相、柱状相、球状相的演化过程。发现柱状相和球状相有多种演化途径,以及相互作用参数对体系演化速度的影响。径向分布函数是表征体系空间有序度的重要方法,但是很少被用于分析耗散粒子动力学模拟的体系。在本论文中,我们借助于径向分布函数,对比分析了各种不同有序形貌中聚合物粒子间以及聚合物和溶剂的相对位置关系,从定量的角度分析了各有序形貌的微观差异,以及相互作用参数对有序相间距的影响。更多还原

【Abstract】 Block copolymers are a type of macromolecules composed of a series of different repeating units linked together. Because of the incompatibility between different structural units, the blocks repel each other. On the other hand, the repeating units are connected by chemical bonds, and microphase separation can occur. Block copolymers, in bulk and in selective solvents, can self assemble into a number of ordered morphologies, such as lamellar, hexagonally packed cylinders, spherical, and even more complicated structures such as vesicles, complex micelles, ring micelles, multicompartment micelles and so on. In addition to the flexible block copolymers, a series of rod-coil and rod block copolymers are also synthesized. Studies show that copolymers with rigid blocks have distinct self-assembly behavior, which can be used in optics, microelectronics, membrane engineering and etc.Computer simulation has been widely used to study chemical problems. It not only supports experiments in explaining the phenomena and clarifying microscopic mechanism, but can also guide experiments. Dissipative particle dynamics method is a kind of coarse-grained simulation method. It contains fluid interaction, conservation of momentum, and employs soft potential to enable large integration time step, and has been widely used in the study of self-assembly of block copolymers. In this thesis, we apply dissipative particle dynamics to examine the self-assembly behavior of a diblock copolymer (with a certain degree of rigidity) in a selective solvent. We computed the phase diagram as a function of the concentration and the interaction parameters between the particles, and examined their effect on the location and regional size of each ordered phase. In addition, the evolution of ordered phase is very important for studying the microscopic mechanism and guiding for experiments, therefore, we investigated the evolution process of lamellar, cylinders and spherical phase. Results show that there is a variety of evolution process for cylinders and spherical phase, and the effect of interaction parameter on the evolution of ordered structures. Radial distribution function is an important tool to characterize the degree of spat ial order, but has been rarely used in analyzing dissipative particle dynamics results. I n this thesis, we use the radial distribution function to analyze the relative position of t he particles in different ordered phases, getting a quantitative understanding of the mi croscopic information of the ordered morphologies. In addition, we also study the effe ct of the interaction parameters on the distance between ordered morphologies.更多还原