钠米颗粒在环形高分子熔体中的集聚—分散转变及复杂囊泡在剪切流场中的动力学行为

发布时间：2018-03-07 22:08

本文选题：环形高分子　切入点：纳米粒子　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：纳米粒子/高分子复合材料由于具有独特的光学、电学、力学性质而在许多科研和技术领域有着重要应用。一般地,纳米粒子在高分子中的分散性好坏会很大程度决定材料的性能。人们做了一系列研究来实现纳米粒子分散最优化,常用的方法为纳米粒子表面嫁接高分子以及改变高分子和纳米粒子间的相互作用强度。环形高分子的特殊的拓扑结构,使其具有很多不同于线形高分子的性质。对环形高分子熔体中纳米粒子行为的研究,可能会发现新的有趣现象。第二章中,我们发现,改变环形高分子的刚性,可以实现纳米粒子/环形高分子复合材料中纳米粒子由集聚-分散的转变,完全不同于线形高分子熔体中纳米粒子由各向同性的球形集聚转变为线形集聚。这是由于半刚性环形高分子熔体中,纳米粒子间的平均有效作用势势能随刚性增加由短程吸引变成了排斥,且纳米粒子周围环形高分子单体浓度较高。而对纳米粒子周围环形高分子的研究,我们发现环形柔性链为径向分布,而半刚性环形刚性链却由于拓扑性质包裹在纳米粒子周围。半刚性环形高分子覆盖在纳米粒子周围使得其它纳米粒子被屏蔽在外,促成了纳米粒子的分散。这一发现为我们改善纳米粒子在纳米复合材料中的分散性提供了新的思路。囊泡在流场中的动力学行为由于和许多生物过程密切相关,而引起了广泛关注。研究发现干净的单个囊泡在剪切流场中存在三种运动方式:翻滚、摇摆与坦克踩。真实的囊泡表面往往装饰了如多糖、蛋白质等生物大分子,有些细胞表面还带有鞭毛。此外,囊泡与囊泡间静电、碰撞等复杂的相互作用也能影响囊泡的动力学行为。这些复杂囊泡在剪切流场中可能出现新的运动方式,对其的深入研究能加深我们对某些复杂的生物过程的理解。第三章,我们研究了二维囊泡膜表面嫁接高分子或者小囊泡后在剪切流场中的动力学行为,发现囊泡除了那三种经典运动方式外,在嫁接链或小囊泡尺寸最够大时,在较高剪切率下还出现了由坦克踩向平移运动方式的转变。此外,嫁接点的位置以及嫁接小囊泡的数目都会对新运动方式的出现产生影响。单个囊泡在剪切流场中的运动方式可以用于描述稀相囊泡悬浊液中囊泡的行为。而半稀相或非稀相囊泡悬浊液中囊泡彼此间存在相互作用(如碰撞、吸引),运动方式更加复杂,而对于这类囊泡在流场中的动力学行为的研究很少。第四章模拟了两个相互吸引的三维囊泡在剪切流场中的动力学行为。发现弹性囊泡存在四种不同的运动运动方式:结合的翻滚,结合的摇摆,碰撞/转动混合,以及分离的坦克踩。其运动方式是由剪切流场同囊泡之间的吸引的竞争结果决定的。而对于很难形变的刚性囊泡,其运动方式则相对简单。第五章,我们探讨了不同形状纳米盘在球壳表面的自组装行为。发现只有在球壳弹性适中时,纳米盘才能在球壳表面形成稳定有序的自组装结构。而对于不同形状和不同数目的纳米盘,最终形成的自组装结构也会有不同。之后我们进一步研究了不同长度和数目的纳米棒在球壳表面的自组装行为。发现纳米棒除了可以形成丰富的自组装结构,还能调控球壳形变为球形、曲边三角体形、椭球形、类似枕头形或者无规则形状。
[Abstract]:The nanoparticles / polymer composite materials with unique optical, electrical, and mechanical properties in many scientific and technological fields have important applications. In general, the dispersion of nanoparticles in the polymer will largely determine the performance of the material. They made a series of research to realize the nanoparticle dispersion optimization, commonly used methods for grafting the surface of nanoparticles and polymer polymer nanoparticles and change the interaction strength. The topological structure of special ring polymer, which has many different from the linear polymer properties. Research on behavior of polymer melt in ring shaped nanoparticles, may find new interesting phenomena. In chapter second, we found that the change of the rigid ring polymer can be achieved, nanoparticles / polymer composite nanoparticles in annular transition from agglomeration and dispersion, completely different from the Linear nanoparticles in polymer melt by spherical isotropic cluster into linear cluster. This is due to the semi-rigid ring in polymer melt, the average effective potential energy between the nanoparticles with increasing rigidity by short-range attraction turned around the ring shaped nanoparticles and exclusion, the higher concentration of monomer and polymer. The nanoparticles around the ring polymer research. We found that the annular flexible chain for radial distribution, and semi rigid rigid annular chain but due to topological properties wrapped in nanoparticles around. Semi rigid ring polymer covered on the nanoparticles so that other nanoparticles are shielded in around, contributed to the nanoparticles dispersed. This discovery provides a new way for us to improve the dispersion of nano particles in nano composite materials the vesicles in the flow dynamics due and is closely related to many biological processes, and The study found that a single capsule widely. There are three kinds of clean bubble motion in shear flow: roll, swing and tank tread. True vesicle surface often decoration such as polysaccharides, proteins and other biological macromolecules, some cell surface with flagella. In addition, vesicles and vesicles between electrostatic. Interaction of the complex can also influence the dynamic behavior of the vesicles. These vesicles appear complex movement of new possibilities on the shear flow field, this in-depth study can deepen our understanding of some complex biological processes. In the third chapter, we study the two-dimensional surface grafting polymer membrane vesicles or vesicles after in the shear flow field of the dynamic behavior, found that in addition to the three classic vesicle movement, the grafting chain or vesicle size is large enough, the high shear rate has emerged from the tank down on the translational movement mode Change. In addition, grafting position and the number of grafting vesicles will appear on the new movement influence. Movement of single vesicles in shear flow field can be used to describe dilute vesicle vesicle suspensions. The behavior of semi dilute or non dilute vesicle interactions exist between each other vesicle suspensions (such as collision, movement, attraction) is more complex, but little research on dynamic behavior of the vesicles in the flow field. The fourth chapter simulates the two three capsule attract each other in shear flow dynamic behavior. It was found that the elastic vesicles in the presence of four different exercises with the combination of: roll, swing, rotation and collision / mixing, separation tank tread. The movement is composed of shear flow with vesicles of the attraction between the competition results of the decision. It is difficult for the deformation and rigid capsule bubble movement The way is relatively simple. The fifth chapter, we discuss the different shapes of nano disk in the self-assembly behavior of spherical shell surface. Found only in the elastic spherical shell, can form self-assembled nano disk stable structure in the shell surface. For different shapes and different number of disk, the final form of the self assembly the structure will be different. Then we further studied the length and the number of nanorods on the self-assembly behavior of spherical shell surface. In addition to the formation of self-assembled nanorod found rich structure, but also regulate the deformation of spherical shell is spherical, three curved angle shape, ellipsoid, pillow shaped or similar irregular shape.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O631;TB383.1

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