两亲嵌段共聚物的合成及其自组装研究进展

作者介绍了两亲嵌段共聚物的活性阴离子聚合、基团转移聚合、开环歧化聚合、活性阳离子聚合、活性／可控自由基聚合、缩聚法、嵌段共聚物化学改性法等合成方法,并对其自组装形成聚合物纳米胶束的制备方法、形成机理以及在药物控制释放领域的应用进行了综述,并对其未来发展趋势进行了展望。     

丙烯腈嵌段共聚物的合成及其自组装研究进展

综述了含聚丙烯腈(PAN)嵌段共聚物的合成方法及其在溶液中的自组装技术。对常用的活性自由基聚合方法,如原子转移自由基聚合(ATRP)、可逆加成断裂链转移(RAFT)聚合、氮氧自由基聚合(NMP)以及钴调介自由基聚合(CMRP)等方面的研究进行了总结,同时对PAN类嵌段共聚物在溶液中的自组装技术进行了概括。最后提出了现有技术存在的问题,并对其今后发展方向进行了展望。     

嵌段共聚物自组装中的缺陷研究进展

嵌段共聚物自组装形成的各种有序相结构中都不可避免地包含有缺陷。由于相结构单元是高分子链段聚集而成的"域"而非传统意义上的原子,导致传统晶体中的缺陷理论无法有效解释嵌段共聚物自组装中的缺陷。因此,研究嵌段共聚物中的缺陷对软物质材料的应用具有重要意义。本文综述了嵌段共聚物体系中的几类典型缺陷的研究进展,重点介绍了我们在圆柱受限下单螺旋结构的缺陷调控以及六角排列柱状结构中5～7缺陷演化方面的研究工作。     

环境响应性两亲嵌段共聚物的自组装及其药物控释研究进展

两亲嵌段共聚物形成的胶束、囊泡等典型的自组装体可作为纳米医药载体,用于药物的控释,其研究已成为当前胶化、医药和生物学科交叉领域的热点。尤其是聚乙二醇型两亲嵌段共聚物,不仅具有良好的生物相容性,而且通过适当的分子设计可形成对环境具有刺激响应的纳米载体。本文着重综述了这类两亲嵌段共聚物的自组装及其在药物控释方面的研究,总结了影响自组装的因素,并介绍了控释药物的机理。     

含聚乙二醇的嵌段共聚物的合成及自组装研究进展

综述了通过活性自由基聚合如原子转移自由基聚合（ATRP）、氮氧稳定自由基聚合（NMP）、可逆加成断裂链转移聚合（RAFT）等方法合成含聚乙二醇（PEG）的嵌段共聚物的研究进展,并对含PEG类嵌段共聚物在溶液中的自组装技术和在药物载体、介孔材料以及碳纳米管中的应用进行了归纳,指出含PEG的嵌段共聚物可以自组装成多种形貌,直接影响材料的性能和应用,所以这些结构有潜在的应用价值和应用前景,并且合成新的含PEG的嵌段共聚物和开发具有新型结构、形貌可控的自组装体以及新的应用领域是今后的一个热点问题,具有重要的科学研究意义和实际应用价值。     

几何受限下的嵌段共聚物自组装

嵌段共聚物通过自组装可以形成特定的周期性纳米结构,然而这些有限种类的体相结构却无法有效满足实际应用中的众多需求.为丰富嵌段共聚物自组装的纳米结构库,几何受限的引入是最为有效的方法之一.几何受限改变了体相结构的平移对称性,嵌段高分子为了缓解这一破坏带来的结构受挫,从而形成更多的新相结构.本文以AB两嵌段高分子为例,从本体...     

通过RAFT法制备双亲性嵌段共聚物及诱导自组装行为

通过可逆-加成断裂链转移自由基聚合(RAFT)成功制备了聚甲基丙烯酸甲酯-聚丙烯酸叔丁酯嵌段共聚物(PMMA-b-PtBA),在三氟乙酸的作用下选择性水解,得到聚甲基丙烯酸甲酯-聚丙烯酸双亲性嵌段共聚物(PMMA-b-PAA),利用1HNMR,FTIR和GPC对两种产物的结构进行了表征。将Ln3+稀土离子与PMMA-b-PAA通过"配位诱导"作用在THF溶剂中形成配合物胶束,并用TEM和DLS测定了胶束的形貌和粒径。结果表明,共聚物与稀土离子配位而发生交联,导致配合物胶束粒径比单纯共聚物的胶束粒径明显增大。     

嵌段共聚物自组装中的异相成核技术

利用嵌段共聚物自组装获得有序纳米结构一直以来都是新材料领域备受关注的热点问题.嵌段共聚物的无序-有序相变,也是系统从成核到分相的过程.异相成核概念的引入,可以实现自组装结构的可控生长,从而获得目标结构.本文首先分析传统均相成核过程中相分离的影响因素,以此设计出基于异相成核概念的有特定取向的诱导势场,从而实现了大尺度有序...     

嵌段共聚物的合成及其组装行为

嵌段共聚物在选择性溶剂中可逆缔合形成以不溶性链段为核 ,溶解性链段为壳的胶束。广泛用作表面活性剂、增溶剂、药物载体和纳米材料等。综述了嵌段共聚物的合成方法 ,着重分析了浓度、温度、嵌段长度、溶剂、添加物及电荷等因素对嵌段共聚物在选择性溶剂中组装行为的影响及其形成机理。展望了嵌段共聚物组装行为的应用前景     

两亲性嵌段共聚物的合成及其自组装行为

采用原子转移自由基聚合（ATRP）方法合成了两亲性嵌段共聚物PSt-b-PAA。用1H NMR和GPC等手段对活性聚合进行了确认,对嵌段共聚物的结构进行了表征。两亲性嵌段共聚物在离子液体1-丁基-3-甲基咪唑六氟磷酸盐（[BM IM][PF6]）中形成胶束溶液。用透射电子显微镜（TEM）观察聚合物在离子液体中形成胶束的纳米结构。当疏水链长固定时,胶束的自组装形状主要依赖于亲水链的长度。两亲性共聚物在离子液体中可自组装成可控制结构的纳米胶束,这种纳米胶束可应用在很多领域。     

Synthesis, characterization and self-assembly behavior of six-armed star block copolymers with triphenylene core

Hexa-armed star block copolymers, s-[poly(l-lactide)-b-poly(styrene-co-N-acryloxysuccinimide)]₆ (s-[PLLA-b-poly(St-co-NAS)]₆) with triphenylene core have been successively prepared by the combination of ring-opening polymerization and atom transfer radical copolymerization, and they were used in the self-assembly in tetrahydrofuran, and the micelles with triphenylene core and PLLA as inner layer as well as poly(St-co-NAS) as shell were formed. After shell was cross-linked, PLLA was hydrolyzed in aqueous NaOH solution, the hollow spheres were formed. The structures, molecular weight and polydispersity index of the polymers were characterized by their ¹H NMR and FT-IR spectra, as well as GPC. Their morphologies were studied by TEM. The influence factors on the formation of various morphologies are under investigation.     

刚柔嵌段共聚物聚苯基喹啉-b-聚苯乙烯的合成

利用原子转移自由基聚合合成了端羧基聚苯乙烯,然后与4-氨基苯乙酮反应,生成末端为乙酰基的聚合物,以P2O5为催化剂,将功能化的聚合物与5-乙酰基-2-氨基二苯甲酮共聚,合成出刚柔嵌段共聚物聚苯基喹啉-b-聚苯乙烯(PPO-b-PS),用红外光谱(IR)、氢核磁共振(1HNMR)和热重分析(TGA)对其结构和性能进行了表征,并在三氟乙酸／二氯甲烷混合溶剂中进行了初步的自组装研究。     

Polyaldehydes: homopolymers,block copolymers and promising applications

This minireview gives a brief overview on the polymerization of higher aldehydes, discusses current applications of certain polyaldehydes, and points toward potential future applications of these interesting materials. Although it was discovered long ago that several aldehydes can be polymerized, the application potential of these polymers was largely overlooked. This is somewhat surprising as many polyaldehydes show interesting properties such as fast and complete depolymerization triggered by chemical or thermal stimuli. Such stimuli‐responsive polymers can be useful materials in many applications in for example nanotechnology or drug delivery. By incorporating polyaldehydes into functional block copolymers even more versatile materials can be created. The increasing number of recent research examples demonstrates the growing interest in polyaldehydes as smart materials and their potential for novel applications. Copyright © 2012 Society of Chemical Industry     

Directed self-assembly of block copolymers by chemical or topographical guiding patterns: Optimizing molecular architecture,thin-film properties,and kinetics

Patterning strategies based on directed self-assembly (DSA) of block copolymers, as one of the most appealing next-generation lithography techniques, have attracted abiding interest. DSA aims at fabricating defect-free geometrically simple patterns on large scales or irregular device-oriented structures. Successful application of DSA requires to control and optimize multiple process parameters related to the bulk morphology of the block copolymer, its interaction with the chemical or topographical guiding pattern, and the kinetics of structure formation. Most studies have focused on validating DSA patterning techniques using PS-b-PMMA block copolymers as a prototypical material. As the development of DSA techniques advances, recent efforts have been devoted to extending the materials selection in order to fabricate more complex geometric patterns or patterns with smaller characteristic dimensions. How to select appropriate polymer materials in a vast parameter space is a critical but also challenging step. In this review, we discuss recent progress in the research of DSA of block copolymers focusing on three aspects: (i) screening the block copolymer materials, (ii) controlling the film properties, and (iii) tailoring the phase separation kinetics.     

Semifluorinated ABA triblock copolymers: Synthesis,characterization, and amphiphilic properties

In this study a series of novel semifluorinated ABA triblock copolymers with different fluorinated segment lengths and different fluorocarbon side‐chain structures were synthesized via atom transfer radical polymerization (ATRP) and macroinitiator techniques. The macroinitiator, telechelic bromine terminated polystyrene, was obtained from bulk ATRP of styrene with α,α′‐dibromo‐p‐xylene as the initiator and cuprous bromide/α,α′‐bispyridine complex as the catalyst. The polymerization reactions of 2‐[(perfluorononenyl)oxy] ethyl methacrylate and ethylene glycol monomethacrylate monoperfluorooctanoate were initiated by the macroinitiator in the presence of additional catalyst. The characterization of the block copolymers was performed by gel permeation chromatography, ¹H‐NMR spectroscopy, and differential scanning calorimetry. The surface activities of the block copolymers in toluene were investigated with the Wilhelmy plate method. The solid surface energy of the block copolymers was determined by measurement of the contact angles. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2625–2633, 2002     

Surface properties of block and graft polystyrene–polydimethylsiloxane copolymers

The surface compositions of a series of polystyrene‐b‐polydimethylsiloxane (PS‐b‐PDMS) and polystyrene‐g‐polydimethylsiloxane (PS‐g‐PDMS) copolymers were investigated using ATR‐FTIR and XPS technique. The results showed that enrichment of PDMS soft segments occurred on the surface of the block copolymers as well as on that of graft copolymers. And the magnitude order of the enrichment was as follows: PS‐b‐PDMS > PS‐g‐PDMS, which was attributed to the facilitating of the movement of the PDMS segments in PS‐b‐PDMS copolymer. Meanwhile, the solvent type and the contact medium had influence on the accumulation of PDMS on the surfaces. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Encapsulation of phenylacetic acid in block copolymer nanoparticles during polymerization induced self-assembly

Polymerization induced self-assembly (PISA) is an in situ method for producing block copolymer nanoparticles. Performing PISA in the presence of a pharmaceutical drug causes the nanoparticles to encapsulate the drug. While this approach is straightforward, the effects of drug loading and block copolymer composition remain unclear. Here, we investigate encapsulation of the drug phenylacetic acid (PA) in poly(glycerol monomethacrylate)-block-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA) nanoparticles during PISA. Nanoparticle morphology is characterized by electron microscopy and light scattering, while encapsulation efficiency ($p$) is quantified using nuclear magnetic resonance diffusometry. Increasing the PA loading shifts the nanoparticle morphology from spherical micelles $\to$ cylindrical micelles $\to$ vesicles. At a 32 mg/ml PA loading, $p$ maximizes at ~80%. Increasing the PHPMA degree of polymerization minimally impacts $p$. The invariance of $p$ toward core block length suggests that PA binds to the nanoparticle corona, highlighting the importance of the hydrophilic block for drug encapsulation during PISA.     

Crystallization assisted self-assembly of semicrystalline block copolymers

The self-assembly of block copolymers (BCPs) in the presence of crystallization as the second driving force is reviewed, for BCPs in the bulk, thin films, single crystals and micelles. The crystallization of semicrystalline BCPs in the bulk is introduced briefly and the unique morphologies of semicrystalline BCPs at various levels due to crystallization are discussed. The thin film morphologies shown by crystalline BCPs are summarized in terms of the factors affecting the relative strengths of various driving forces. Special attention is paid to the thin film morphologies of functional BCPs containing crystalline poly(3-alkylthiophene) and perylene bisimide units. The single crystal morphologies of semicrystalline BCPs are also presented. Finally, the micellar morphologies of BCPs with a semicrystalline core are reviewed. The controlled and living growth of crystalline micelles, which is the unique characteristic of such micelle, is then discussed.     

Conjugated rod-coil block copolymers: Synthesis, morphology, photophysical properties, and stimuli-responsive applications

Conjugated rod-coil block copolymers have been accorded great importance since they provide a powerful route towards supramolecular objects with novel architectures, functions and physical properties. This review summarizes recent progress on the synthesis, morphology, optoelectronic properties and applications of such block copolymers. The combination of the precise condensation and living polymerization through the grafting-from or grafting-onto methodology produce various architectures of conjugated rod-coil block copolymers, including rod-coil, coil-rod-coil, rod-coil-coil, and rod-coil-rod. In the following, the relationships between polymer morphologies and photophysical properties in different phases are reviewed, as classified by solution micelles, thin films or bulk samples, polymer brushes and electrospun nanofibers. The effects of the rod/coil ratio and polymer architecture on the morphology and optoelectronic properties are discussed. The control of nanosize domain and the aligned direction of conjugated rods are the key issues for enhancing the optoelectronic device performance. Moreover, novel multifunctional sensory materials based on combining the tunable photophysical properties of the π-conjugated rod and the stimuli-responsive coil are also highlighted. It is believed that conjugated rod-coil block copolymers could spark the future evolution of nanostructured polymers for multifunctional device applications.