【作者】 刘观峰；

【导师】 黄建花；

【作者基本信息】 浙江理工大学 ， 应用化学， 2012， 硕士

【摘要】 近年来，含有各向异性纳米棒的材料成为现代材料科学的一个重要研究方向。大量研究结果表明：各向异性无机纳米棒的组装结构受到生长条件、基底表面性质和胶体浓度等因素的影响。同时纳米棒能形成液晶相，使得嵌段共聚物/各向异性无机纳米棒以及rod-coil-rod三嵌段共聚物体系的组装行为变得复杂。因而对这些体系的组装机理和组装结构的影响因素仍需进一步探讨，但目前关于这方面的计算机模拟和理论还鲜有报道。本文主要采用Monte Carlo方法和耗散粒子动力学方法模拟研究纳米棒、嵌段共聚物/纳米棒和rod-coil-rod三嵌段共聚物的组装结构和组装机理，主要包括三个部分：（1）纳米棒的组装行为；（2）嵌段共聚物/纳米棒的组装结构的影响因素；（3）考察rod-coil-rod三嵌段共聚物组装机理及主要影响因素。全文共分为六章：第一章介绍纳米单元、嵌段共聚物以及嵌段共聚物/纳米粒子组装的研究进展，以及相关的计算机模拟研究成果。第二章介绍Monte Carlo方法和耗散粒子动力学方法的基本原理及应用，并对本论文中所用的模型及方法进行说明。第三章详细研究各向异性作用(头-尾作用ε_z，肩-肩作用ε_xy)对纳米棒组装行为的影响。在r=ε_z/ε_xy很小和很大时纳米棒分别组装成1D线和2D板。r为中间值时，纳米棒从无序到3D柱状结构的聚集过程中发生一级相变，相变温度Tc受作用势ε_xy和ε_z共同决定。3D柱状结构的长径比与作用势比值r呈指数关系A=0.238r⁽2.13±0.05/_。指数值不同于理论预测是由于在组装过程中水平方向上更多的作用对引起的动力学影响的结果。第四章考察了影响嵌段共聚物/纳米棒的组装结构的因素。研究结果发现混合体系组装结构受链段与纳米棒相互作用、嵌段共聚物浓度以及纳米棒浓度的影响，通过变化纳米棒浓度诱导六方柱结构向柱/层的混合相转变，最后转变为层结构，模拟结果与实验报导相符。组装结构的变化是由于纳米棒之间的各向异性作用和混合体系的协同作用共同引起的。第五章考察了rod-coil-rod三嵌段共聚物在稀溶液中的组装结构，组装过程以及影响组装结构的主要因素。在rod-coil-rod三嵌段共聚物囊泡形成过程中，首次观察到双层板结构卷曲形成囊泡的动力学过程。第六章为全文的总结和展望。更多还原

【Abstract】 Recently, anisotropic nanorods in material science are increasingly becoming one ofimportant research topics in material science. A large amount of researches show thatsuperlattices of nanorods are dominated by many factors including growth conditions, nature ofsubstrate surface and colloidal concentration. The self-assembly of nanorods/copolymers androd-coil-rod block polymers becomes more complex, because nanords can form liquidcrystalline phases. Therefore, further investigations should be carried out to discover theassembling mechanism of these systems.In this thesis, the self-assembly behavior of nanorods, diblock polymers/nanorods androd-coil-rod block copolymers, as well as the effects on their self-assemblied structures wereinvestigated by dynamic Monte Carlo method and dissipative particle dynamics （DPD）simulation. Firstly, the assembly of nanorods was studied in detail, then the influences of theinteraction between copolymer-nanorod, the polymer concentration and the nanorodconcentration on the assembled strucutures of polymer/nanorod mixtures were investigated. Atlast, the self-assembly of rod-coil-rod triblock copolymers in dilute solution was studied byDPD simulations. The thesis is divided into six chapters as following:Chapter1introduced the progress of experiments, theoretical studies and computersimulations on the systems of nanorod, copolymer/nanorod and rod-coil-rod triblockcopolymer.Chapter2introduced the principle of Monte Carlo method and DPD method. The relativeapplication and the model used in this thesis were also elucidated.In Chapter3, the effect of anisotropic interaction on the assembly behavior of nanorodswas investigated.1D nanowires and2D sheet are assembled at a very small and large value of r=ε_z/ε_xy, respectively. Here, zand xyrepresent the end-to-end and side-by-side interactionbetween nanorods, respectively. At intermediate values of r, a first-order phase transition fromdisorder to3D pillar takes place. The transition temperature Tcdepends on both interactions xyand z. The aspect ratio A of3D pillar structure is in power-law relation with the interactionratio r asA0.238r2.130.05. The exponent is different from that of theoretical prediction, which may be due to the kinetic effect resulted from more attraction pairs in the lateral directionin the assembly process.Chapter4presented the simulation result of diblock copolymer A₅B₅/nanorod mixtures.The attraction between block A-nanorod, the concentration of A₅B₅s and nanorods are found toexert a dramatic effect on the morphology of A₅B₅/nanorod hybrids. With an increase of thenanorod concentration, the morphology of A₅B₅/nanorod mixture changes from hexagonalcylinders to lamellar structure.Chapter5investigated the self-assembly of rod-coil-rod triblock copolymers in dilutesolution. A vesicular structure is assembled when the concentarion of copolymers A4B16A4is inthe range of0.75-0.20. The formation mechanism of vecisle has been investigated in detail. Thevesicle is formed through the following pathway: a bilayer disk is developed from a randomlydispersed system, it then bends and encapsulates solvents and finally closes to form a vesicle,which is the first observation for the rod-coil-rod triblock copolymers.A summary was given in Chapter6.更多还原