两亲嵌段共聚物的合成及纳米自组装

首先用苄氧羰基赖氨酸和三光气反应合成苄氧羰基赖氨酸酸酐,然后将聚乙二醇中活性较弱的羟基转化为氨基,最后以双端氨基聚乙二醇作为引发剂,采用阴离子开环聚合合成了聚(Nε-苄氧羰基赖氨酸)-聚乙二醇-聚(Nε-苄氧羰基赖氨酸)(PLL(Z)-PEG-PLL(Z))。PLL(Z)-PEG-PLL(Z)经去保护后得到带正电荷的聚赖氨酸-聚乙二醇-聚赖氨酸(PLL-PEG-PLL)。PLL(Z)-PEG-PLL(Z)在水溶液中自组装形成的聚集体类似于纳米多孔聚集体结构,具有疏松的空洞,原子力显微镜观测其呈球形,其大小为220 nm左右。     

嵌段共聚物自组装模板--构造纳米结构的一种新方法

纳米结构的构造在整个纳米科技中有着特殊重要的意义．如何低成本、大规模地实现纳米结构材料的控制合成与组装一直是纳米加工中的热点问题．高分子嵌段共聚物分子结构独特，包含着热力学不相容的不同高分子嵌段，并由化学键相连．通过控制外界条件，嵌段共聚物可以自组装成高度规则的超分子结构，特征尺寸为10nln～100nm．以嵌段共聚物膜自组装相分离图案为模板，或把这种图案复制到其它材料上，通过刻蚀等技术可以制备纳米结构模板，再经纳米铸造得到相应结构的纳米材料和纳米器件，文中主要介绍嵌段共聚物自组装模板的原理、模板图案的调控方法和模板应用，并详细阐述了各自的发展状况。     

通过嵌段共聚物自组装制备哑铃状Au-Fe304纳米粒子排列

通过嵌段共聚物自组装制备哑铃型Au-Fe3O4纳米粒子排列,先通过旋涂含有哑铃型纳米粒子（DBNPs）的聚苯乙烯-b-聚（2-乙烯基吡啶）（PS—b—P2VP）混合溶液得到复合薄膜,再将复合薄膜在高温下退火,实验发现,无论是预先合成的表面带有油酸基团,还是11-巯基十-烷酸修饰的哑铃型纳米粒子,都可以选择性的进入到PS—b—P2VP嵌段共聚物中的P2VP柱状微区中。实验结果表明,在退火过程中,哑铃型纳米粒子可以进入到嵌段共聚物中的一个微区中,并不取决于其表面的化学性质。     

柱状两嵌段共聚物在纳米碗中的自组装

采用动态密度泛函理论,对本体为柱状相的两嵌段共聚物受限于纳米碗中的相行为进行了模拟研究。考察了纳米碗大小和表面作用强度对自组装纳米结构的影响。通过逐渐增大纳米碗直径和衬底相互作用,一方面再现了两嵌段共聚物受限于硅纳米碗实验中出现的纳米结构(单球结构、圆环与中心球结构、六角排列的球结构),另一方面,对碗状受限空间和表面诱导可能出现的新结构进行了预言。此外,利用序参量对自组装过程的物理机制进行了分析。     

聚合诱导自组装制备形貌多样的ABA型三嵌段共聚物微/纳米粒子

以聚N,N-二甲基丙烯酰胺(PDMA)为大分子链转移剂、苯乙烯(St)为单体,采用可逆加成-断裂链转移(RAFT)分散聚合制备了PDMA-b-PS-b-PDMA两亲性三嵌段共聚物胶束.考察了固含量和疏、亲溶剂链段比对胶束尺寸、形貌的影响.固含量为25％和30％时,胶束形貌转化过程是从球状、蠕虫状向囊泡状胶束发展,最终得...     

刚柔嵌段共聚物自组装制备有序孔材料研究进展

综述了刚柔嵌段共聚物自组装机理，以及近年来利用刚柔嵌段共聚物自组装制备有序孔材料的发展状况，指出刚柔嵌段共聚物制备有序孔材料的影响因素，认为刚柔嵌段共聚物自组装有着广阔的应用前景。     

聚烷基噻吩嵌段共聚物合成及自组装的研究进展

立构规整性聚烷基噻吩具有很好的光电特性及很高的溶解度等优点,使得该材料被应用于有机场效应晶体管、化学传感器及光伏太阳能电池等领域。介绍了立构规整性聚烷基噻吩均聚物及其棒杆-线团、棒杆-棒杆型嵌段共聚物的合成及自组装行为的研究进展,并对聚烷基噻吩嵌段共聚物的发展前景进行了展望。     

自组装软模板法制备有序中孔炭研究进展

通过介绍自组装软模板法制备有序中孔炭的发展历程和基本原理,说明该方法具有操作简单、成本低、易于控制等优点。重点评述了自组装软模板法制备有序中孔炭在产物形貌控制和多级孔结构制备方面的研究进展,分析认为,今后的研究可以在拓展前驱体范围、提高宏观产物柔韧性以及导电性等方面得到进一步发展。     

高分子自组装掩膜的制备

利用高分子共混物的微相分离和自组装原理,采用溶液共混和旋转涂膜的方法制得聚苯乙烯/聚甲基丙烯酸甲酯(PS/PMMA)高分子共混物薄膜,对薄膜经过再加工得到具有纳米微孔的PMMA薄膜,研究了对溶液进行超声处理的时间、PS/PMMA共混物溶液浓度、旋涂转速和试片表面对掩膜形貌的影响。以此PMMA薄膜为掩膜对GaP表面进行湿法腐蚀,得到一种蜂窝状的表面微结构,它能使发光二极管(LED)的光功率平均提高18%。     

纳米结构苯胺/吡咯共聚物的静态法合成及自组装

采用静态聚合法,以过硫酸铵为氧化剂,使苯胺与吡咯进行共聚,制备了高产率(88%)的纳米结构苯胺/吡咯(PANPY)共聚物。研究结果发现,苯胺/吡咯摩尔比和聚合介质对共聚物的形貌有重大影响。以1.0 mol/L盐酸溶液为介质,苯胺/吡咯摩尔比为90/10时,可制得直径为70 nm～90 nm、长为1.3μm的共聚物纳米纤维;苯胺/吡咯摩尔比为50/50时,得到平均粒径约为400 nm的杨梅球状共聚物颗粒,透射电子显微镜的结果表明这些杨梅球状共聚物颗粒是由直径为5nm,长25nm的共聚物微小纳米纤维自组装而成。而以0.1 mol/L NaOH水溶液为反应介质,则可以得到外直径为1.8μm～2.6μm的自组装共聚物微球。     

自组装法制备聚合物纳米复合膜的新进展

介绍了自组装法制备聚合物纳米复合膜的几种最新技术；化学吸附法、分子沉积法、旋涂法。这些方法操作简单，膜的结构稳定性较高，利用它们可以制备各种功能化的聚合物纳米复合膜，从而实现薄膜的光、电、磁、非线性光学等的功能化。由此，这些方法受到国内外的广泛重视。     

分子自组装体系的影响因素及其在纳米材料中的应用

介绍了分子自组装体系的影响因素以及分子自组装技术在纳米材料制备方面的应用,并对聚合物自组装体系及研究进展作了综述.     

纳滤膜纯化球状大分子的可行性研究

分析了球状大分子合成中的目标产物难分离难纯化的特点，采用纳滤膜分离技术纯化新型纳米材料——球状大分子；通过HPLC和元素分析测试了纯化前后的纯度，证明了纳滤膜是可以提高目标球状大分子的纯度；孔径较大的NF1膜有利于乙二胺的透过，其纯度提高较大，而孔径较小的NF2膜对乙二胺的透过能力下降，所以纯度提高较小。     

Phosphorylation and sulfation share a common biosynthetic pathway,but extend biochemical and evolutionary diversity of biological macromolecules in distinct ways

Phosphate and sulfate groups are integral to energy metabolism and introduce negative charges into biological macromolecules. One purpose of such modifications is to elicit precise binding/activation of protein partners. The physico-chemical properties of the two groups, while superficially similar, differ in one important respect—the valency of the central (phosphorus or sulfur) atom. This dictates the distinct properties of their respective esters, di-esters and hence their charges, interactions with metal ions and their solubility. These, in turn, determine the contrasting roles for which each group has evolved in biological systems. Biosynthetic links exist between the two modifications; the sulfate donor 3′-phosphoadenosine-5′-phosphosulfate being formed from adenosine triphosphate (ATP) and adenosine phosphosulfate, while the latter is generated from sulfate anions and ATP. Furthermore, phosphorylation, by a xylosyl kinase (Fam20B, glycosaminoglycan xylosylkinase) of the xylose residue of the tetrasaccharide linker region that connects nascent glycosaminoglycan (GAG) chains to their parent proteoglycans, substantially accelerates their biosynthesis. Following observations that GAG chains can enter the cell nucleus, it is hypothesized that sulfated GAGs could influence events in the nucleus, which would complete a feedback loop uniting the complementary anionic modifications of phosphorylation and sulfation through complex, inter-connected signalling networks and warrants further exploration.     

An energetic model for macromolecules unfolding in stretching experiments

We propose a simple approach, based on the minimization of the total (entropic plus unfolding) energy of a two-state system, to describe the unfolding of multi-domain macromolecules (proteins, silks, polysaccharides, nanopolymers). The model is fully analytical and enlightens the role of the different energetic components regulating the unfolding evolution. As an explicit example, we compare the analytical results with a titin atomic force microscopy stretch-induced unfolding experiment showing the ability of the model to quantitatively reproduce the experimental behaviour. In the thermodynamic limit, the sawtooth force–elongation unfolding curve degenerates to a constant force unfolding plateau.     

纳米ZnO的研究及其进展

纳米ZnO的许多优异性能使其成为人们研究的热点并得到广泛的应用。随着ZnO颗粒尺度的不断减小，其量子限域效应越来越明显，观察到电荷载流子，声子，光子的局域化效应；表面、界面态对其性质影响逐渐明显，通过表面修饰和置入多孔及束管等束缚结构，可有效增强ZnO紫外（一个量级）或可见光区（1－2个量级）的发射强度；并使ZnO的电导率，磁化率有很大提高，纳米ZnO与其他材料的复合体系能得到一些新的功能材料。纳米ZnO的自组织行为，使人们可以获得许多形态各异，特殊用途的纳米材料及器件。本文综述了近年来纳米ZnO的研究新动态。     

J-Aggregation of an anionic oxacarbocyanine in electrostatically self-assembled multilayers

Unlike in water solution, interaction of the anionic oxacarbocyanine E (structure in Fig. 1) with three polycations electrostatically adsorbed on a quartz substrate results in an extensive J aggregation of the dye. J-aggregates grow on the film surface beyond charge saturation, making possible the formation of alternately adsorbed polycation/E multilayers. UV-visible absorption and fluorescence spectra have revealed that, although less ordered than in solution, J aggregates are dominant in dry films. They are characterized by some heterogeneity and exhibit a reorganization dynamics in the presence of water. Polarized absorption has shown that the J-band transition-dipole moments lie preferentially parallel to the film plane, thus suggesting a plausible arrangement for a bidimensional brickwork aggregate. An exploration of the effects of various preparation variables (solution concentrations and ionic strengths, dipping times, film drying speed, polycation nature and molecular weight) has afforded some insight into the processes involved in polycation/J-aggregate multilayer formation.     

Recent developments in anionic polymerization

The past year witnessed very significant advances in the living anionic polymerization of (meth)acrylate monomers, particularly in hydrocarbons at or below 0°C. Block polymerization of alkyl methacrylates with primary alkyl acrylates, although somewhat improved, remains a challenge. Anionic polymerization of styrene, diene and its derivatives was carried out with the aim of synthesizing functional polymers and block copolymers of various architectures. There has been a trend towards combining different living techniques in order to design polymers of unique architectures and properties     

Recent developments in explosive welding

Explosion welding (EXW) is one of the joining methods consisting of a solid state welding process in which controlled explosive detonation on the surface of a metal. During the collision, a high velocity jet is produced to remove away the impurities on the metal surfaces. Flyer plate collides with base plate resulting in a bonding at the interface of metals. The metal plates are joined at an internal point under the influence of a very high pressure and causes considerable local plastic deformation at the interface in which metallurgical bonding occurs in nature and even stronger than the parent metals. Similar and dissimilar materials can be joined by explosive welding. In this paper, after detection the theories of welding and wave formation, experimental research and numerical studies on explosive welding are reviewed for the last four decades. Also, future developments in explosive welding are predicted and criticized in an outlook.     

Recent developments in ultrasonic fatigue

The recently increased interest in very high cycle fatigue properties of materials has led to extended use and further development of the ultrasonic fatigue testing technique. Specimens are stimulated to resonance vibrations at ultrasonic frequency, where the high frequency allows collecting lifetime data of up to 10¹⁰ cycles and measuring crack propagation rates down to 10^?12 m per cycle within reasonable testing times. New capabilities and methods of ultrasonic testing and outstanding results obtained since the year 1999 are reviewed. Ultrasonic tests at load ratios other than R = ?1, variable amplitude tests, cyclic torsion tests and methods for in situ observation of fatigue damage are described. Advances in testing at very high temperatures or in corrosive environments and experiments with other than bulk metallic materials are summarized. Fundamental studies with copper and duplex steel became possible and allowed new insights into the process of very high cycle fatigue damage. Higher cyclic strength of mild steels measured at ultrasonic frequency because of plastic strain rate effects are described. High‐strength steels and high‐alloy steels are less prone to frequency influences. Environmental effects that can lead to prolonged lifetimes in some aluminium alloys and possible frequency effects in titanium and nickel and their alloys are reviewed.