刺激响应性刚柔嵌段共聚物的自组装

刚柔嵌段共聚物是指刚性链段和柔性链段以共价键相连形成的共聚物。不仅由于刚性链段有序排列的特点使得其自组装行为更为丰富多样,而且刚性分子将优异的功能特性赋予到超分子组装体中,有望实现超分子材料的功能应用。这类嵌段共聚物在溶液中自组装形成的聚集体会对外界的刺激(例如pH、光、温度、化学添加剂等)敏感,产生聚集体形态的变化。本文选取了部分典型的具有刺激响应性的刚柔嵌段共聚物,介绍了其智能自组装行为,并对其良好的发展前景做了展望。     

DNA-多肽复合分子的设计、组装与应用

DNA-多肽复合分子作为一类新型的自组装分子受到研究人员的广泛关注。DNA分子具有可编程性、高特异性、功能多样等优点,多肽分子是一类重要的生物小分子,能够通过分子自组装形成具有不同结构的纳米材料,因此,将二者通过共价交联,可以获得具有多级自组装行为的DNA-多肽复合分子,能够实现两类重要生物分子功能的集成优化,合成具有不同结构与功能的超分子自组装材料。此外,通过酶催化、DNA杂化、DNA链置换反应等,还可实现对多肽-DNA复合分子自组装行为的动态调控,进而模拟生命系统中复杂动态的自组装结构,强化相关材料在生物、化学、材料等领域的应用。本文讨论了DNA-多肽复合分子的设计、组装与应用方面的最新进展,最后基于目前DNA-多肽复合分子存在的一些问题对DNA-多肽复合分子的研究做了展望。     

嵌段共聚物自组装的研究进展

自组装是分子间通过非共价键相互作用自发组合形成的一类结构明确、稳定,同时具有某种特定功能或性能的分子聚集体或超分子结构的现象.嵌段共聚物不仅可以在本体中自组装,还能在溶液中自组装.本文综述了嵌段共聚物在溶液中自组装的规律及其主要影响因素,包括嵌段共聚物链段长度、选择性溶剂的性质、嵌段共聚物的浓度、溶液的pH值等;并介绍...     

可结晶共聚物的分子建模及其应用

共聚是调控高分子材料结晶性能的有效手段,因而共聚物链单元的序列结构对其结晶行为的影响机制是高分子结构与性能关系研究中的重要科学问题.本文从可结晶共聚物链单元序列化学结构的分子建模出发,围绕无规共聚物和嵌段共聚物序列结构对其结晶行为的调控机制,总结了近年来采用动态蒙特卡罗(Monte Carlo)分子模拟方法所开展的相关研究进展.以静态条件下温度调控结晶和动态条件下应变诱导结晶这两个方面为脉络,本文结合线型低密度聚乙烯结晶、两嵌段共聚物自组装受限结晶和热塑性弹性体取向诱导结晶等典型应用案例,旨在表明有效的分子建模有助于研究人员深入理解共聚物结晶的微观调控机制,从而更好地从事高分子材料的基础研究和应用开发.     

全亲水性嵌段共聚物及其超分子自组装

本文介绍了全亲水性嵌段共聚物(DHBCs)的定义与特点.根据不同的环境敏感自组装机理,分类详述了不同DHBCs的结构及其超分子自组装行为,并探讨了相应的应用现状与前景.     

双刚性共轭嵌段共聚物体系的自组装

棒杆-棒杆(rod-rod)共轭嵌段共聚物体系是近几年发展起来的一类新型共轭聚合物材料,由于其特有的电学活性以及通过自组装实现纳米尺度结构可控等特性正逐渐成为人们研究的热点.构筑单元的刚性棒状结构使得rod-rod共轭嵌段共聚物体系倾向于自组装形成囊泡或层状结构等低曲率聚集体.本文总结了近年来关于rod-rod共轭嵌段共聚物体系自组装行为的研究,分别介绍了溶液中以及薄膜状态下双刚性共轭嵌段共聚物体系的自组装行为,在此基础上进一步讨论了rod-rod共轭嵌段共聚物薄膜结构与性能的关系.     

两亲性聚(L-谷氨酸γ-苄基酯)-聚乙二醇接枝共聚物的自组装行为和载药性能研究

由氨基酸及其衍生物聚合形成的聚肽,因其独特的结构和性能,近年来在蛋白质结构模拟、分子链构象研究、生物医学等领域备受关注．其中两亲性聚肽共聚物的自组装行为,为开发具有生物相容性、可控释、可降解性的新型药物载体创造了条件．目前对聚肽共聚物自组装及载药性能研究主要集中于聚肽嵌段共聚物胶束,     

多酸-有机聚合物超分子自组装杂化材料

多酸具有多样的拓扑结构和优异的理化性质,在催化、光电材料和药物等领域显示出广阔的应用前景。多酸-有机聚合物超分子自组装杂化材料不仅有效融合了多酸丰富的功能特性和有机聚合物良好的加工性,而且其有序的自组装结构还赋予材料更多优异的功能调控性。静电复合、氢键作用、共价键连等超分子策略是将多酸引入到聚合物基质中的有效方法。本文总结了多酸-有机聚合物超分子杂化材料近几年的最新研究进展,重点介绍了这类杂化材料的构筑策略、其有序的自组装行为以及超分子功能特性的调控等。     

嵌段共聚物三维软受限自组装

嵌段共聚物在三维软受限条件下能够组装形成结构有序的聚合物胶束,其在催化、电子器件、光学传感等领域有广泛的应用价值,已经引起了广大科研工作者的关注。众所周知,嵌段共聚物自身性质及组装体内部结构和外部形状都会显著影响嵌段共聚物组装体性质及应用。本文简述了近年来嵌段共聚物三维软受限自组装的方法,分析了影响嵌段共聚物组装结构的内在和外在因素,内在因素主要指嵌段共聚物自身性质,包括嵌段共聚物种类、分子量及嵌段比;外在因素主要包括受限空间尺寸、界面性质、热或溶剂退火等。本文讨论了无机纳米粒子与嵌段共聚物三维软受限共组装,探讨了纳米粒子引入对组装结构影响及其在嵌段共聚物组装体中的分布及排列规律,以及组装结构的潜在应用。最后还讨论了目前嵌段共聚物三维软受限自组装存在的问题,同时对未来的发展方向进行了展望。     

寡肽自组装纳米材料研究进展

肽类自组装是自然界普遍存在的分子自组装现象之一,研究其自组装行为对理解生命现象、仿生制备以及构建功能材料等具有重要的意义.寡肽由于合成简单,结构组成明确,同时具有良好的生物相容性、可控的降解性,其组装体在药物/基因控制释放、细胞培养、组织工程支架材料及生物矿化等领域具有很大的应用前景.本文概述了近年来寡肽自组装的研究进展,系统介绍了线性和环状寡肽的分子结构设计、自组装体形貌及组装机理以及组装体在生物医学等领域的应用.     

Fabrication of functional nano-objects via self-assembly of nanostructured hybrid materials

A simple route to fabricate functional nano-objects via self-assembly of block copolymer-based hybrid materials is described. In water–toluene mixtures, spheres, rod-like morphologies, and ring-like morphologies as well as vesicles of metal loaded block copolymers micelles are fabricated. The concept is generic to realize different functionalities by incorporating various inorganic components (Au, Ag, Pt, Co…) into the block copolymer matrix. A mechanism describing the formation of micellar aggregates with different morphologies is presented based on a simple force balance approach. Moreover, the composition of the solvent mixture is modified to gain control over the morphology of micellar aggregates. It was found that swelling of the micelle core with a selective cosolvent is the driving force to induce morphology transitions from spherical to rod- and ring-like structures as well as vesicles. These nano-objects can be further used as building blocks to construct well-defined structures via self-assembly in spin coated thin films. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1642–1650, 2010     

Crystallization-driven self-assembly of semicrystalline block copolymers and end-functionalized polymers: A minireview

Self-assembly has been a powerful method to fabricate the polymer materials with well-defined structures and morphologies. Such assembled materials have shown wide potential applications in many fields such as nanomaterial, nanomedicine, lithography, and microelectronic. Crystallization has been a general behavior of stereoregular polymers. Besides the various noncovalent interactions, crystallization of polymer blocks or end groups can be an efficient way to manipulate the self-assembly pathway and assembled structures of polymers in both solid and solution. Crystallization-driven self-assembly has been widely implemented for the semicrystalline block copolymers (BCPs) and end-functionalized polymers. This minireview briefly presents the recent progresses in the crystallization-driven self-assembly of BCPs and end-functionalized polymers in both solid and solution states. Formation process, mechanism, and hierarchical structure of the crystallization-induced assemblies for BCPs and end-functionalized polymers are highlighted.     

Self-assembly of polypeptide-based copolymers into diverse aggregates

Recently, increasing attention has been given to the self-assembly behavior of polypeptide-based copolymers. Polypeptides can serve as either shell-forming or core-forming blocks in the formation of various aggregates. The solubility and rigidity of polypeptide blocks have been found to have a profound effect on the self-assembly behavior of polypeptide-based copolymers. Polypeptide graft copolymers combine the advantages of a grafting strategy and the characteristics of polypeptide chains and their self-assembly behavior can be easily adjusted by choosing different polymer chains and copolymer architectures. Fabricating hierarchical structures is one of the attractive topics of self-assembly research of polypeptide copolymers. These hierarchical structures are promising for use in preparing functional materials and, thus, attract increasing attention. Computer simulations have emerged as powerful tools to investigate the self-assembly behavior of polymers, such as polypeptides. These simulations not only support the experimental results, but also provide information that cannot be directly obtained from experiments. In this feature article, recent advances in both experimental and simulation studies for the self-assembly behavior of polypeptide-based copolymers are reviewed.     

由嵌段共聚物制备有形状的核壳结构聚合物纳米颗粒

嵌段共聚物可自发组装形成形貌丰富的纳米粒子和有序纳米结构的材料,为纳米材料和纳米技术领域提供了很重要的新材料和新手段.该领域的进一步发展提出了对嵌段共聚物的自组装体赋予功能性的要求,即需要通过可控聚合反应合成反应性嵌段共聚物,并且对其自组装的纳米粒子进行结构、形状及功能性的调控.本文针对以上研究目标,结合本课题组在该领...     

Phase diagrams,mechanisms and unique characteristics of alternating-structured polymer self-assembly via simulations

Alternating-structured polymers(ASPs), like alternating copolymers, regular multiblock copolymers and polycondensates, are very important polymer structures with broad applications in photoelectric materials. However, their self-assembly behaviors,especially the self-assembly of alternating copolymers, have not been clearly studied up to now. Meanwhile, the unique characteristics therein have not been systematically disclosed yet by both experiments and theories. Herein, we have performed a systematic simulation study on the self-assembly of ASPs with two coil alternating segments in solution through dissipative particle dynamics(DPD) simulations. Several morphological phase diagrams were constructed as functions of different impact parameters. Diverse self-assemblies were observed, including spherical micelles, micelle networks, worm-like micelles, disklike micelles, multimicelle aggregates, bicontinuous micelles, vesicles, nanotubes and channelized micelles. Furthermore, a morphological evolutionary roadmap for all these self-assemblies was constructed, along with which the detailed molecular packing models and self-assembly mechanisms for each aggregate were disclosed. The ASPs were found to adopt a folded-chain mechanism in the self-assemblies. Finally, the unique characteristics for the self-assembly of alternating copolymers were revealed especially, including(1) ultra-fine and uniform feature sizes of the aggregates;(2) independence of self-assembled structures from molecular weight and molecular weight distribution;(3) ultra-small unimolecular aggregates. We believe the current work is beneficial for understanding the self-assembly of alternating structured polymers in solution and can serve as a guide for the further experiments.     

Soft confinement-induced morphologies of diblock copolymers

The self-assembly of diblock copolymers under soft confinement is studied systematically using a simulated annealing method applied to a lattice model of polymers. The soft confinement is realized by the formation of polymer droplets in a poor solvent environment. Multiple sequences of soft confinement-induced copolymer aggregates with different shapes and self-assembled internal morphologies are predicted as functions of solvent-polymer interaction and the monomer concentration. It is discovered that the self-assembled internal morphology of the aggregates is largely controlled by a competition between the bulk morphology of the copolymer and the solvent-polymer interaction, and the shape of the aggregates can be non-spherical when the internal morphology is anisotropic and the solvent-polymer interaction is weak. These results demonstrate that droplets of diblock copolymers formed in poor solvents can be used as a model system to study the self-assembly of copolymers under soft confinement.     

Tandem interactions in the self-assembly of ionic block copolymers

The aim of the present review is to show how the phenomena of block copolymer self-assembly and interactions of ionic (or ionizable) groups in polymer systems can be combined to produce materials with versatile and unique behavior. In our discussion, we consider two classes of tandem interactions. First, block copolymers containing short ionic blocks and long nonionic blocks are investigated in organic media. In systems of this type, block copolymer self-assembly and short-range electrostatic interactions act in tandem, forming regular and highly-stable spherical structures. Next, we consider ionic (or ionizable) block copolymers dissolved in aqueous media. In this case, block copolymer self-assembly acts in tandem with the hydrophilic nature of the soluble blocks, resulting in a wide range of unique morphologies.     

Self-assembled morphologies of diblock copolymers confined in nanochannels: effects of confinement geometry

The self-assembly of diblock copolymers confined in channels of various shaped cross sections is studied using a simulated annealing technique with the "single-site bond fluctuation" model. In the bulk, the asymmetric diblock copolymers used in this study form hexagonally packed cylinders with period L0. The cross sections of the confining channels are of different shapes including regular triangles, rectangles, squares, regular hexagons, regular octagons, and ellipses. For a given geometry, the channel size (characterized by one or two lengths) is varied from very small to several times of L0. It is found that the geometry and size of the confining channels have a large effect on the structure and symmetry of the self-assembled morphologies. Multiple packed cylinders with the symmetry of the confining channels are the major morphologies for low-symmetry cross sections such as triangle, rectangle, and square. More complex structures such as helices or stacked toroids spontaneously form when the confining channels are shaped such as a regular hexagon, a regular octagon, or an ellipse. The domain spacing of the self-assembled structures can be altered by the shape and size of the confining channels. Our results are consistent with available experiments. These results indicate that the self-assembled structures of block copolymers can be manipulated by the shape of the confining channels.     

Hierarchical Self-Assembled Photo-Responsive Tubisomes from a Cyclic Peptide-Bridged Amphiphilic Block Copolymer

Typically, the morphologies of the self-assembled nanostructures from block copolymers are limited to spherical micelles, wormlike micelles and vesicles. Now, a new generation of materials with unique shape and structures, cylindrical soft matter particles (tubisomes), are obtained from the hierarchical self-assembly of cyclic peptide-bridged amphiphilic diblock copolymers. The capacity of obtained photo-responsive tubisomes as potential drug carriers is evaluated. The supramolecular tubisomes pave an alternative way for fabricating polymeric tubular structures, and will expand the toolbox for the rational design of functional hierarchical nanostructures.     

Synthesis and dissipative particle dynamics simulation of cross-linkable fluorinated diblock copolymers: self-assembly aggregation behavior in different solvents

Developing microstructures, such as low molecular aggregates, spherical micelles and multi-compartment micelles, is an expanding area of research in Materials Science. By applying an atom transfer radical polymerization (ATRP) process to cross-linkable fluorinated diblock copolymers and analyzing the data we are able to demonstrate the potential for developing films with different micro-structures for additional biological research. Applying the Dissipative Particle Dynamic (DPD) Method, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) techniques to cross-linkable fluorinated diblock copolymers of (methyl methacrylate-co-hydroxyethyl methacrylate-co-butyl methacrylate)-b-2-(perfluoroalkyl)ethyl methacrylate (MMA-co-HEMA-co-BMA-b-FMA) we were able to analyze the structures and their relationships to the aggregation of various microstructure formations through the use of various solvents in the process. For the self-assembly of the cross-linkable diblock copolymer in solutions, the DPD simulation results are only in qualitative agreement with experimental data of aggregate morphologies and sizes. This suggests an improved approach to creating materials and methods necessary for studying microstructures in films used in other research areas. Our work examines whether using selective solvents can be easily extended to prepare aggregates with different morphologies, which is an effective shortcut to obtain films with different microstructures. DPD simulation can be considered as an adjunct to experiments and provides other valuable information for the experiment.