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题名: 两亲性三嵌段共聚物在选择性稀溶液中的自组装及应用
作者: 朱锦涛
学位类别: 博士
答辩日期: 2005
授予单位: 中国科学院长春应用化学研究所
授予地点: 中国科学院长春应用化学研究所
关键词: 两亲性嵌段共聚物 ; 自组装 ; 胶束 ; 纳米材料 ; 选择性溶剂
其他题名: Self-assembly and Application of the Amphiphilic Triblock Copolymers in Selective Dilute Solution
学位专业: 高分子化学与物理
中文摘要: 本论文主要研究了ABA和ABC型两亲性三嵌段共聚物在选择性稀溶液中的自组装行为,得到了多种形态新颖、结构复杂多样的胶束,研究了这些复杂胶束的形成过程,探讨了影响胶束形态的各种因素并通过适当的方法对胶束形态进行调控。研究了聚乙烯基毗陡(P4VP)/聚苯乙烯(PS)三嵌段共聚物P4VP-b-PS-b-P4VP在二氧六环/水中的自组装行为,成功得到了嵌段共聚物环状胶束,并通过实验研究了环状胶束的形成过程。结果表明,胶束形态依赖于退火时间的长短。随着退火时间的延长,胶束结构从棒状过渡到环形结构。以实验结果为基础提出了环状胶束形成的新的机理,即囊泡塌陷形成环。同时,通过改变实验条件还得到了一些新型的环状复合结构,如环套环形、鸟状、哑铃形、戒指形、网络状等结构,并得到了与计算机模拟一致的结果。通过不同的方法对ABA型三嵌段共聚物(P4VP-b-PS-b-P4VP)在选择性溶液中的自组装胶束形态进行调控:首先,详细研究了P4VP-b-PS-b-P4VP在不同的共溶剂中的自组装行为。结果表明通过单纯改变共溶剂的性质可以很方便地调节胶束的形态,得到了球、棒、囊泡等结构。并用混合溶剂的方法得到了长度和直径可控的纳米线胶束。同时,通过加入第二种选择性溶剂(核层嵌段PS的选择性溶剂甲苯)的方法使形成胶束的核层嵌段在胶核中的伸展程度增加,从而使胶束形态发生转变。其次,研究了加入表面活性剂十五烷基苯酚(PDP)以构建分子间氢键来调节P4VP-b-PS-b-P4VP的胶束形态。结果表明,通过调节PDP的加入量可以使胶束形态发生从球到棒,到网络状、再到囊泡结构的转变。通过实验对比系统地研究了PDP的加入对胶束形态转变的影响,提出了相应的形态转变机理。再次,研究了不同分子量的嵌段共聚物之间共混及共聚物与均聚物共混对胶束形态的影响。结果表明加入亲油嵌段的均聚物对共聚物胶束形态影响非常明显,胶束形态与加入的均聚物的分子量及加入量直接相关。同时得到了一些新形态的胶束,如海绵状、笼子状等。共聚物共混的研究结果表明:通过两种不同分子量的共聚物共混可以得到这两种共聚物胶束的过渡态结构。用共聚物混合的方法还可以得到一些具有生物模拟性的胶束结构,如乌贼状、章鱼状等。这加深了人们对囊泡的形成机理及各种胶束形态之间形态转变的认识。P4VP-b-PS-b-P4VP通过在二氧六环/水中的自组装形成了囊泡,结果表明囊泡的尺寸依赖于初始状态下共聚物在共溶剂中的浓度及退火时间。除得到常规的球形囊泡外,还得到一些非球形囊泡,如长条形、三角形、项链形等囊泡结构。结合计算机模拟的方法研究了囊泡的形成机理,发现这些不同结构的囊泡的形成是由于初始状态下密度涨落所引起的。研究了实验中经常出现的各种胶束形态共存现象的原因,发现体系中亚稳态的存在是多形态共存的重要原因之一。通过聚苯乙烯一左聚乙烯基毗睫一左聚氧乙烯(PS一b一PZVP一b一PEO)在THF/水中的二次自组装首次得到了一种具有生物模拟性的巨大的节状蠕虫胶束(SWM)。研究发现,SWM是由重复单元盘状结构和丝状结构相连组成的。最令人吃惊的是这种SWM与自然界中的一些生命体如蛆叫、蛹、昆虫类的幼虫结构非常相似。通过对SWM形成过程中的中间态胶束结构的深入研究发现SWM是由球形胶束通过二次自组装形成的。SWM的形成过程可以分为三个阶段:ABC三嵌段共聚物先组装形成球形结构;这些球型结构粘连在一起形成梭形的中间结构;这些梭状中间结构中的球经过重组和重新调整各嵌段的排布最终形成SWM。用所得到的嵌段共聚物胶束为模板,采用无电沉积的方法成功制备了各种形态的金属一有机高分子纳米复合材料。用简单的方法还得到了导电金属金一银的双金属纳米结构材料。这些纳米结构材料在微电子器件等领域有潜在应用价值。以上研究结果丰富了人们对嵌段共聚物在选择性介质中自组装行为的理解,为人们提供了对生物材料自组装本质的理解的依据。这在两亲性分子在溶液中自组装的基础研究方面以及基于这些自组装形态而构建结构及功能更复杂的纳米结构材料等方面都有一定的意义。
英文摘要: In this dissertation, we systematically investigated the self-assembly of ABA and ABC amphiphilic triblock copolymers in selective dilute solution and found various previously unknown complex micellar morphologies. In addition, we studied the micellar formation process and discussed the factors which affect the aggregate morphologies. The micellar morphologies were tuned by manipulating the related parameters. We investigated the self-assembly of amphiphilic polystyrene/poly(4-vinypyridine) triblock copolymer P4VP-6-PS-6-P4VP in dioxane/water mixed solution and found novel morphology-ring-shaped morphology. The ring formation process was studied and found that the micellar morphology depends on the annealing time. It changes from rod structure to ring-shaped structure with increasing annealing time. Based on the experimental results, we proposed a new ring formation mechanism, i.e., collapse of vesicles. In addition, we have found some novel compound ring-shaped micellar morphologies by changing the experimental method, such as ring-ring nesting, bird-like, dumbbell-like, finger-ring-like, network among others. The results correlate well with computer simulative ones. The micellar morphologies of ABA triblock copolymer (P4VP-6-PS-6-P4VP) in dilute solution were tuned by using the following methods: Firstly, we gave a thorough investigation on the self-assembly of P4VP-6-PS-6-P4VP in different common solvent. The results indicated that the micellar morphologies can be conveniently tuned into spheres, rods, vesicles, et al. by changing the common solvent properties individually. The lengths and diameters of the nanowires can be controlled by tuning the properties of the mixed common solvent. Meanwhile, the micellar morphologies transition would occur when we added a selective solvent (toluene) for the core-forming blocks (PS blocks) which can increase the stretching of the core-forming blocks. The micellar morphologies can be tuned by using this method. Secondly, we tuned the aggregate morphologies of P4VP-6-PS-6-P4VP through hydrogen bonding (between PDP and P4VP blocks) by adding a surfactant, i.e., pentadecyl phenol (PDP) into the copolymer solution. The aggregate morphologies were found to be changed from spheres to rods, network and looped structures, and then to vesicles and compound vesicles by increasing the PDP adding amount at the same concentrations as the PDP free copolymer solutions. We proposed a morphological transition mechanism based on the parallel experimental results. Thirdly, effect of copolymers (with different molecular weight) blending and homopolymer of core-forming blocks (PS blocks) addition to the copolymer system on the micellar morphologies was investigated. It was found that the micellar morphologies were sensitive to the homopolymer addition to the copolymer solution. The micellar morphologies depended on the molecular weight and adding amount of the homopolymer. The results of copolymer blending indicated that intermediate structure can be obtained by binary blending copolymers with different molecular weight. The micellar morphologies depended on the ratio of the copolymer in the mixtures. Some biomimetic structures, such as cuttle-fish like, octopus-like micelles were obtained through this method. These structures are important for the study of vesicles formation and micellar morphology transitions. Self-assembly of P4VP-6-PS-6-P4VP into vesicles in dioxane/water was studied and found that the size of the vesicles depended on the initial concentration of the copolymer in common solvent and the annealing time. Besides the normal spherical vesicles, we found some non-spherical vesicles, such as long-style, trigonal and necklace-like vesicles in our experiments. The results show that various vesicles in dilute solution are formed solely on account of the inhomogeneous density distribution in local region in nature. Our results confirm that structural complexity coexisting behavior in the single-amphiphile systems is largely attributed to the metastability rather than the polydispersitv of the triblock copolymer. We investigated the self-assembly of a linear ABC amphiphilic triblock copolymer PS-6-P2VP-6-PEO in THF/water and found a previously unknown architecture of giant biomimetic segmented worm-like micelles (SWMs). Our results show that the SWMs comprised sequences of repeated elemental parts, i.e. disks. A most interesting feature is that disks having different diameters became connected through threads to form various giant biomimetic SWMs, which resemble such organisms as earthworms, pupae and larvae. A kinetic study indicated the ABC triblock copolymer aggregates to form spherical micelles through primary self-assembly. The results indicated that the process of SWM formation occurred basically through three stages: (1) the ABC triblock copolymer self-assembled into small spheres; (2) these small spheres joined together to form intermediate shuttle-like structures; (3) the spheres within the shuttle-like structures rearranged and underwent further adjustment to form the final SWMs. We successfully fabricated various metallized nanostructures by coating metallic nanolayers onto the soft self-assembled nanotemplates through simple electroless plating methods. In particular, bimetallic nanostructures have been obtained by using simple methods. These nanomaterials and the bimetallic materials with different structures are potentially active materials in different fields, such as micro-electric devices and sensors. These findings enrich our knowledge of the potential for the self-assembly of amphiphiles in selective media and are important for understanding the origin of self-assembly in biomaterials. We believe that these findings are also important in understanding the self-assembly of amphiphiles in selective solvent and for fabricating functional complex nanomaterials based on the self-assembles.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ciac.jl.cn/handle/322003/34531
Appears in Collections:长春应用化学研究所知识产出_学位论文

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Recommended Citation:
两亲性三嵌段共聚物在选择性稀溶液中的自组装及应用.朱锦涛[d].中国科学院长春应用化学研究所,2005.20-25
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