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1.
Hierarchical nanoporous structures are fabricated by adsorption of micelles of diblock copolymer‐templated Au‐nanoparticles onto a hydrophilic solid substrate. Gold nanoparticles are prepared using micelles (19 nm) of polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP) as nanoreactors. Deposition of thin films of the micellar solution, modified with a non‐selective solvent (THF), on hydrophilic surfaces leads to the formation of hierarchical nanoporous morphologies. The thin films exhibit two different pore diameters and a total pore density of 15 × 108 holes per cm2. The structure was analyzed in terms of topography and chemical composition using AFM, TEM and XPS measurements. The PS‐b‐P4VP template was subsequently removed by oxygen plasma etching, to leave behind metallic nanopores that mimic the original thin film morphology.

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2.
近年来,嵌段共聚物在受限空间中的自组装已成为高分子科学领域一个新的关注点.在受限条件下,嵌段共聚物展现出更多的可调控性,可获得复杂多样的微相分离结构.这些新颖的结构为实现嵌段共聚物更加丰富的功能奠定了材料基础.中国的学者们在嵌段共聚物受限自组装的理论模拟和实验研究方面取得了一系列重要创新成果,有力地推动了该领域的发展.本文总结和评述了中国学者在该领域的研究进展,并展望了嵌段共聚物受限自组装研究未来发展的机遇与挑战.  相似文献   

3.
Summary: The free‐radical addition of ω‐functional mercaptans to the vinyl double bonds of 1,2‐polybutadiene‐block‐poly(ethylene oxide) copolymers was used for modular synthesis of well‐defined functional block copolymers. The modification reaction proceeds smoothly and yields quantitatively functionalized block copolymers (1H NMR and FT‐IR spectroscopy) without disturbing the molecular‐weight distribution of the parent copolymer (PDI < 1.09, size exclusion chromatography).

The modular synthetic pathway towards the functional block copolymers reported here.  相似文献   


4.
The graft‐through synthesis of Janus graft block copolymers (GBCPs) from branched macromonomers composed of various combinations of homopolymers is presented. Self‐assembly of GBCPs resulted in ordered nanostructures with ultra‐small domain sizes down to 2.8 nm (half‐pitch). The grafted architecture introduces an additional parameter, the backbone length, which enables control over the thermomechanical properties and processability of the GBCPs independently of their self‐assembled nanostructures. The simple synthetic route to GBCPs and the possibility of using a variety of polymer combinations contribute to the universality of this technique.  相似文献   

5.
Mixed-graft block copolymers (mGBCPs) consist of two or more types of polymeric side chains grafted on a linear backbone in a random, alternating, or pseudo-alternating sequence. They can phase-separate with the backbone serving as the interface of the blocks, and the side chains dominate their self-assembly behavior. mGBCPs are an accessible polymer architecture for exploring the idea of encoding polymer properties through the macromolecular architecture, as there are two distinct structural components that can be tuned: the backbone and the side chains. In this Concept article, the current literature on the synthesis of mGBCPs is reviewed, and the advantages and disadvantages of each synthetic method are noted. The self-assembly of mGBCPs is also discussed where possible. Finally, directions for future research on mGBCP synthesis and self-assembly are suggested.  相似文献   

6.
This review deals with nanoporous materials made from the self‐assembly of block copolymers with a special interest in the chemical functions covering the surface of their nanopores. A detailed overview of the existing methods and strategies to generate well‐defined organic functional groups covering the surface of the pore walls is provided. This further enables to finely tune the affinity of the pore walls and to perform well‐defined chemical reactions onto them, which is essential for further dedicated applications.

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7.
Block copolymers are a special class of polymers having the ability to self-assemble into nanoscale ordered structures which depend on molecular composition of the blocks. With the aim of studying the influence of copolymer composition, the kinetics of a 4,4′-diaminodiphenylmethane-cured diglycidyl ether of bisphenol-A (DGEBA) epoxy system modified with a PEO-PPO-PEO block copolymers has been investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), taking into account the relation between blocks in the copolymer as well as different copolymer contents. DSC results show that the rate of cure reaction decreases when the copolymer is added, which can be attributed to the interaction between the hidroxyl groups of the growing epoxy thermoset and the ether groups of the block copolymer observed by FTIR. The experimental results obtained have been related to the morphologies observed by atomic force microscopy (AFM).  相似文献   

8.
Helical topological structures are often found in chiral biological systems, but seldom in synthesized polymers. Now, controllable microphase separation of amphiphilic liquid‐crystalline block copolymers (LCBCs) consisting of hydrophilic poly(ethylene oxide) and hydrophobic azobenzene‐containing poly(methylacrylate) is combined with chirality transfer to fabricate helical nanostructures by doping with chiral additives (enantiopure tartaric acid). Through hydrogen‐bonding interactions, chirality is transferred from the dopant to the aggregation, which directs the hierarchical self‐assembly in the composite system. Upon optimized annealing condition, helical structures in film are fabricated by the induced aggregation chirality. The photoresponsive azobenzene mesogens in the LCBC assist photoregulation of the self‐assembled helical morphologies. This allows the construction and non‐contact manipulation of complicated nanostructures.  相似文献   

9.
Thermally reversible nanostructured thermosetting materials are prepared for the first time by modification of an epoxy resin with 5 wt.‐% of an amphiphilic polystyrene‐block‐poly(ethylene oxide) block copolymer (PSEO) and 30 wt.‐% of a low‐molecular‐weight liquid crystal, 4‐(hexyl)‐4‐biphenylcarbonitrile (HBC). The epoxy system modified with 5 wt.‐% PSEO amphiphilic copolymer self‐assembles into spherical microdomains with a size distribution between 32 and 45 nm in diameter. Under the same conditions, the modification of an epoxy system with 5 wt.‐% PSEO and 30 wt.‐% HBC leads to a micro‐phase separated PS‐rich domains embedded in a HBC phase. The morphology of this nanostructured thermosetting system consists in a higher amount of spherical microdomains of PSEO/HBC with the size distribution between 40 and 75 nm in diameter. This implies that the separation of the PS‐rich phase provokes the separation of the liquid crystal and allows one to obtain a novel thermally switchable smart material.

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10.
A diblock copolymer system constituting both achiral and chiral blocks, polystyrene‐block‐poly(L ‐lactide) (PS‐PLLA), was designed for the examination of chiral effects on the self‐assembly of block copolymers (BCPs). A unique phase with three‐dimensional hexagonally packed PLLA helices in PS matrix, a helical phase (H*), can be obtained from the self‐assembly of PS‐rich PS‐PLLA with volume fraction of PLLA f = 0.34, whereas no such phase was found in racemic polystyrene‐block‐poly(D .L ‐lactide) (PS‐PLA) BCPs. Moreover, various interesting crystalline PS‐PLLA nanostructures can be obtained by controlling the crystallization temperature of PLLA (Tc,PLLA), leading to the formation of crystalline helices (PLLA crystallization directed by helical confined microdomain) and crystalline cylinders (phase transformation of helical nanostructure dictated by crystallization) when Tc,PLLA < Tg,PS (the glass transition temperature of PS) and Tc,PLLATg,PS, respectively. As a result, a spring‐like behavior of the helical nanostructure can be driven by crystallization so as to dictate the transformation (i.e., stretching) of helices and to result in crystalline cylinders. For PS‐PLLA with PLLA‐rich fraction (f = 0.65), another unique phase, a hexagonally packed core‐shell cylinder phase with helical sense (CS*), in which the PS microdomains appear as shells and PLLA microdomains appear as matrix and cores, can be found in the self‐assembly of PLLA‐rich PS‐PLLA BCPs. The formation of those novel phases: helix and core‐shell cylinder is attributed to the chiral effect on the self‐assembly of BCPs, so we named this PS‐PLLA BCP as chiral BCP (BCP*). For potential applications of those materials, the spring‐like behavior with thermal reversibility might provide a method for the design of switchable nanodevices, such as nanoscale actuators. In addition, the PLLA blocks can be hydrolyzed. After hydrolysis, helical nanoporous PS bulk and PS tubular texture can be obtained and used as templates for the formation of nanocomposites.

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11.
A PFS/PLA block copolymer was studied to probe the effect of strong surface interactions on pattern formation in PFS block copolymer thin films. Successful synthesis of PFS‐b‐PLA was demonstrated. Thin films of these polymers show phase separation to form PFS microdomains in a PLA matrix, and ultrathin films (<5 nm) formed SINPATs on silicon and mica. The SINPATs consisted of strongly surface‐adsorbed PLA blocks on top of which the PFS blocks dewetted into sphere‐like features. The lateral spacing between these features was regular, and was typically much larger than the length scale associated with regular block copolymer phase separation.

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12.
The effect of crystallization temperature on the micellar morphology of PCL‐b‐PEO block copolymers in water has been studied. It is found that the micellar morphology of PCLnPEO44 and PCLnPEO113 changes with crystallization temperature in different ways because of two competitive factors: perfection of the PCL crystals in the core and deformation of the soluble PEO block. For PCLnPEO44, perfection of the PCL crystals dominates the micellar morphology and lamellar micelles are formed at a higher crystallization temperature. For PCLnPEO113 the micellar morphology is mainly determined by the tethering density and spherical micelles or cylindrical micelles with a larger length/diameter ratio are formed at a higher crystallization temperature because of the larger tethering density.

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13.
In this study, samples of activated mesoporous carbon are fabricated with pore structures with cylinder and gyroid nanostructures through the templating effect of amphiphilic poly(ethylene oxide-block-caprolactone) (PEO-PCL) and by using specific resol/PEO-PCL weight ratios (e.g., 60:40 for cylinders; 55:45 for gyroids). After carbonization and KOH activation, the activated mesoporous carbons were tested as electrode materials for electric double-layer capacitor (EDLC) supercapacitors. The electrochemical properties were examined by using three-electrode (6 m KOH(aq) as electrolyte) and CR2032 coin-cell (1 m tetraethylammonium tetrafluoroborate (TEABF4)/CN as the electrolyte) systems. The gyroid carbon samples provided specific capacitances higher than those of the cylinder carbon samples in both aqueous and organic systems: 155 F g−1 compared with 135 F g−1 in 6 m KOH(aq), and 105.6 compared with 96 F g−1 in 1 m TEABF4/MeCN, after 100 charge/discharge cycles. It is suspected that the bi-continuous mesochannels of the gyroid-type activated mesoporous carbons provided a relatively higher effective adsorption surface area; in other words, the greater surface area for energy storage originated from a moderate pore size and an interconnected pore structure.  相似文献   

14.
Cell‐based therapies are gaining prominence in treating a wide variety of diseases and using synthetic polymers to manipulate these cells provides an opportunity to impart function that could not be achieved using solely genetic means. Herein, we describe the utility of functional block copolymers synthesized by ring‐opening metathesis polymerization (ROMP) that can insert directly into the cell membrane via the incorporation of long alkyl chains into a short polymer block leading to non‐covalent, hydrophobic interactions with the lipid bilayer. Furthermore, we demonstrate that these polymers can be imbued with advanced functionalities. A photosensitizer was incorporated into these polymers to enable spatially controlled cell death by the localized generation of 1O2 at the cell surface in response to red‐light irradiation. In a broader context, we believe our polymer insertion strategy could be used as a general methodology to impart functionality onto cell‐surfaces.  相似文献   

15.
刚柔嵌段共轭聚合物的自组装是超分子化学研究的热点之一。本文综述了近年来刚柔嵌段共轭聚合物自组装体系研究进展。根据共轭刚性段的不同分类进行阐述,综述了聚芴,二(苯乙烯)-蒽,聚对苯撑,聚对苯乙烯撑,聚对苯撑乙炔,聚(2,5-苯甲酮),聚噻吩,聚苯基喹啉等作为刚性链段的刚柔嵌段共轭聚合物自组装体系,介绍了刚柔嵌段共轭聚合物的合成和光物理性质;重点评述了刚柔嵌段共轭聚合物在不同溶剂、浓度、温度等条件下自组装形成一维、二维以及三维的周期性微结构,且具有方便的可控性。概括了刚柔嵌段共轭聚合物自组装体系广阔的应用前景,尤其在光电器件领域有着潜在的应用价值。最后展望了刚柔嵌段共轭聚合物自组装体系研究和发展的方向。  相似文献   

16.
两亲嵌段共聚物溶液自组装新进展   总被引:7,自引:1,他引:7  
综述了两亲嵌段共聚物在溶液中自组装的新进展,重点介绍了两亲嵌段共聚物自组装聚集体中棒状、蠕虫状、囊泡、洋葱和实心洋葱等几种新形态的特点和形成机理;另外对两亲嵌段共聚物溶液自组装在光电、药物释放、靶向以及作为基因工程载体方面的应用前景及两亲嵌段共聚物聚集体的制备方法作了详细的评述。  相似文献   

17.
乙烯醇-醋酸乙烯嵌段共聚物的制备   总被引:1,自引:0,他引:1  
吴永忠 《合成化学》2002,10(5):430-433
采用混合溶剂醇解法制备嵌段聚乙烯醇,考察了混合溶剂甲醇/苯质量百分比,醇解催化剂碱的用量、醇解温度、时间等工艺条件对嵌段特性的影响。在优化条件下制备了嵌段特征为0.4-0.6,表面性能优良的两亲性嵌段聚乙烯醇。  相似文献   

18.
The morphology of a thin film was studied for a binary mixture of asymmetric PS‐b‐PMMA block copolymers on a flat silicon wafer coated with 50 nm thick silicon oxide. AFM and TEM reveal that the PMMA cylinders orient perpendicular to the substrate by tuning the film thickness. Furthermore, grating substrates with different width and depth are used to guide the alignment of the perpendicular cylinders. As a result, an array of highly ordered, hexagonally packed PMMA cylinders in the PS matrix with a domain spacing of less than 25 nm has been produced.

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19.
Mesoscopic simulation techniques are employed to investigate lamellar orientation in block copolymers subjected to oscillatory shear. Dynamic mean‐field density functional theory (MesoDyn) is able to capture parallel lamellar and perpendicular lamellar states at low and higher shear rates. At higher shear rates a third orientation state is identified from cell dynamics and MesoDyn simulations, and corresponds to predominantly parallel‐aligned lamellae. This is explained on the basis of partial shear‐melting at higher shear rates. The results are compared to the lamellar alignment diagram obtained experimentally for polystyrene/polyisoprene block copolymers.  相似文献   

20.
周峻峰  王立  陈涛  王苇 《化学进展》2005,17(6):0-1109
本文介绍两亲嵌段共聚物的合成,综述了经两亲嵌段共聚物自组装制备纳米胶束的研究进展,并对该领域的发展趋势进行了展望。  相似文献   

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