山嵛酸Langmuir膜结合氨气扩散控制生长碱式硝酸锌的分形结构

以山嵛酸(BA) Langmuir膜为仿生矿化模板, 结合氨气动态扩散控制方法, 在气-液界面上制备了取向单一的Zn5(OH)8(NO3)2•2H2O分形结构材料. 利用扫描电子显微镜(SEM)和X射线衍射(XRD)分别对样品形貌及其晶型进行了表征. 结合π-A曲线研究了分形结构生长的驱动力, 并详细分析了分形生长的过程和机理. 认为Langmuir膜的存在导致了材料单一的晶面取向, 而氨气在气-液界面的动态扩散提供了分形结构形成的驱动力. 这有可能为控制合成一系列具有特殊结构的无机晶体材料提供一种可行的方法.     

等规聚丙烯晶区—非晶界面的分形散射

本文基于Tractal理论研究了结晶高聚物结晶—非晶界面,小角x光散射结果表明:该界面具有分形特征,随退火温度升高,界面变平滑,分形维数降低,链折迭更加规整。     

表面非周期有序结构的扫描隧道显微镜研究

基于分子自组装的分形、准晶等非周期有序结构的表面制备在近年来取得了一系列进展.本文综述了基于扫描隧道显微镜对表面谢尔宾斯基三角分形结构和准晶结构的研究.通过改变前驱体类型,可在不同基底上分别实现基于卤键、氢键、配位键、共价键的谢尔宾斯基三角分形结构的制备,并结合模板法和共组装法,突破生长动力学的限制,使得分形结构的级数达到五级.利用羧基间的氢键作用,可通过分子自组装构建表面分子准晶结构,并通过有机分子与稀土原子间的配位作用,成功实现金属有机配位准晶的制备.     

金属电沉积过程中的分形研究

概要地介绍了分形的概念，分形的模型，以及分形与电化学结合在一起，所构成凝聚体电化学生长的实验内容，文章着重叙述了分形在电沉枝晶中的应用。     

透射电子显微镜技术在固态锂电池界面研究中的应用

固态锂电池因高能量密度、高安全性、宽工作温度、长循环寿命及可弹性设计等诸多优点而受到广泛关注。但是界面反应、接触失效和锂枝晶生长等界面问题严重制约了固态锂电池的发展和应用,亟需采用先进的透射电子显微镜技术对固态锂电池界面结构、形态、化学和电子状态进行深入研究。本文概述了电子能量损失谱、球差校正和电子全息等先进技术对固态锂电池界面电荷转移、电位分布和锂枝晶生长等界面问题进行原位和非原位表征的研究进展,并展望了未来透射电镜技术在固态锂电池界面研究领域的发展方向。     

金属锌电沉积过程的分形研究

对金属锌电沉积过程中的二维枝晶生长进行了研究,分析了外加电压、电解质浓度以及温度等实验条件对电沉积产物形貌及其分形维数的影响.结果表明,随着外加电压的增大,沉积产物形貌的变化趋势为由开放的分枝结晶向较为致密的生长形貌转变;随着硫酸锌浓度的增大,沉积产物具有分叉结构的致密纤维状枝晶簇和较为粗壮的开放型规则的分叉状枝晶,分形维数发生相应的变化;随着温度的升高,沉积产物的枝晶呈均匀化、致密化,沉积产物分形维数呈明显增大的趋势.     

表面等离子共振热电子注入机理及在光催化与光电催化应用中的研究进展

由于金属纳米晶表面等离子共振产生的热电子效应,金属/半导体异质纳米晶的可控合成对于增强半导体光催化与光电催化性能具有显著的促进作用。 本综述阐述了热电子产生与驰豫的微观机制,探讨了影响热电子在金属-半导体异质纳米晶中界面传递效率的关键因素及异质界面调控合成的重要性,简要介绍了热电子注入效应在光催化与光电催化制备太阳能燃料研究中的应用进展,分析了目前存在的主要问题并对该领域未来的发展趋势进行了展望。     

非晶态半导体中的分形结构

非晶态半导体硅(α-Si:H)薄膜作为新型的光电子材料,近年来备受关注,发展迅速。但其晶化机理有待深入探索。用分形理论所作的分析表明,在一定条件下,a-Si:H薄膜中形成的微结构具有分形性质。本文计算了分维值,讨论了a-Si:H薄膜结构弛豫(相变)与分形结构形成的关联,和非晶硅薄膜可能的晶化机理。并研究了在高真空中用透射电子显微镜(TEM)及动态方法跟踪观测a-Si:H薄膜原位(in situ)退火过程中发生的晶化现象,获得晶化形貌的显微图像。利用图像处理技术对显微像进行光电转换,A/D转换和数字计算,得到a-Si:H薄膜样品在不同退火条件下,显微象的Sandbox关系曲线。从而获得薄膜中形成不同分形结构的分维。文中给出应用分形理论对非晶态半导体薄膜进行分析的技术细节。     

基于表界面反应及优化的锂金属电池研究进展

金属锂具有高理论比容量和低还原电位, 是锂电池阳极的理想材料之一. 但在长期循环充放电过程中, 金属锂因锂枝晶生长会导致出现界面恶化及能量损失严重等问题, 对锂金属电极与电解质表界面反应的优化是一个重要研究方向. 本文介绍了锂枝晶产生的危害, 从分析及抑制锂枝晶沉积两方面综合评述了为解决这一问题所采取的方法, 包括固态电解质界面形成机制和保护机理、 表面改性、 三维锂阳极和液态/固态电解质等方法, 总结了各种方法的优劣势, 并展望锂金属电池在能源领域的研究前景.     

二维凝胶体系中碳酸钙分形结构的形成与机理研究

本文研究了二维琼脂凝胶圆盘体系中碳酸钙分形结构的形成过程,发现随着反应时间的增加,碳酸钙的形态经过了细小颗粒-枝晶结构-分形结构的转变过程,该分形结构实际上是由纳微米级碳酸钙晶粒聚集而成的。增加琼脂和反应物的浓度,碳酸钙微晶的形貌和尺寸发生了变化,呈现立方体与球形,由其构成的分形结构的尺寸也随着改变,但碳酸钙的晶型均为方解石型,无明显变化。二维凝胶体系中碳酸钙分形结构的形成主要与琼脂极性基团提供成核位点、多糖的网络结构、沉淀剂离子扩散受限有关。     

Dendritic-shaped,fractal hybrid nanogold aggregates mediated by polymer/surfactant complexes on mica surfaces through the salt-induced self-assembly

In this work, we found that the dendritic-shaped, fractal hybrid nanogold aggregates was formed through the salt-induced self-assembly during our attempts to study the self-assembly of gold nanoparticles mediated by polymer/surfactant complex films. The effect of NaCl concentration on the morphology changes of fractal hybrid nanogold aggregates was investigated, and the mechanism of aggregate formation process is briefly discussed. Such fractal patterns enable them to have potential applications in nano-optics. 1 The text was submitted by the author in English. The text was submitted by the author in English.     

分形理论及其在高分子科学中的应用

介绍了分形的基本概念，分形维数的定义及计算方法，讨论了近年来分形理论在高分子科学研究方面的一些应用，内容主要包括高分子溶液、高分子材料的磨损，断裂及界面，高分子结晶过程、导电高分子等。     

The effect of molecular weight of nonadsorbing polymer on the structure of depletion-induced flocs

This work explores the structural compactness of depletion-induced particle flocs with respect to the molecular weight of nonadsorbing polymer flocculants. Small-angle static light scattering was used to monitor the structural characteristics of the flocs, which were formed by the addition of nonadsorbing poly(acrylic acids) to a stable colloidal polystyrene latex dispersion. It was found that the floc mass fractal dimension, considered to be a measure of structural compactness, was dependent upon both the molecular weight and the concentration of the polyacid. In particular, reducing the molecular weight of the polymer at a fixed polyacid concentration resulted in higher mass fractal dimensions, despite the highly polydisperse nature of the polymer samples. This structural behavior was attributed to the lower particle sticking efficiencies upon collision. This reduced sticking ability is the result of the shallowing in the secondary potential energy well with decreasing polymer chain length, which was directly supported by atomic force microscopy data. Our results suggest that the formation of a shallower attraction well with a lower molecular weight nonadsorbing polymer is the result of the insufficiency of the increased osmotic pressure to counter-balance the short-ranged nature of the depletion interaction.     

渗透物在致密聚合物膜中扩散的分形介质模型

利用自由体积理论讨论了渗透物分子在致密聚合物膜内的扩散机理, 提出了“扩散通道”的概念, 建立了渗透物在致密聚合物膜中扩散的分形介质模型, 考虑了自由体积分布对扩散过程的影响. 根据建立的模型, 渗透物在膜内的扩散是由在“扩散通道”上的一系列跳跃构成的. 根据致密膜内扩散通道的关联长度ξ(p)与膜厚L的关系, 可以把扩散分为正常扩散、 过渡扩散和分形扩散三部分, 给出了扩散相图, 提出并解释了分形渡越现象.     

韧性聚合物材料断面分维与断裂韧性

韧性聚合物材料断面分维与断裂韧性吕素平，漆宗能（中国科学院化学研究所工程塑料国家重点实验室，北京，１０００８０）关键词分维，断裂韧性，聚合物，微裂纹，剪切带利用分形几何定量描述材料断面的粗糙特征［１－４］为建立断面形貌与材料韧性间的定量关系提供了可能...     

混合高聚物分相过程标度、分形与Monte Carlo模拟

基于光散射、Monte Carlo模拟标度理论和分形(Fractal)概念研究和分析了高分子混合体系不稳相分离过程结构函数的标度行为和成因, 结果表明相分离的形态是一种分形结构, 其分形维数不随时间变化. 结构函数的标度行为起源于相态的分形结构. 相态的分形结构是不稳相分离特征之一.     

Fractal geometry analysis of chemical structure of natural starch modification as a green biopolymeric product

Public concerns and official pressures around environmental protection as well as exhausting petroleum resources have brought about preferences in studying and applying environmental-friendly polymers instead of synthetic petroleum-based polymers. For this aim, biopolymers can have outstanding advantages in biodegradability by saving time, energy and effort spent on increasingly costs of polymeric wastes. Natural starch (being studied in this work), as one of the most abundant natural resources for polymer materials, is inexpensive and biodegradable. As starch necessarily needs for modifications and processing before being used as ideal green polymer material, it is vital to perform feature extraction and defect detection measures in structure by some method like image analysis. Fractal as a new geometry has circumstantially progressed recently in the fields of image processing, physical space–time, medical image analysis, electrochemical patterns, digital images, sounds etc. Box Count Fractal Dimension as a very important and popular part of fractal geometry can be a useful factor in feature extraction and pattern recognition. This paper presents a new method for defect detection in the structure of natural starch modification images using the fractal dimension (FD) along with mean and standard deviation of image color. This is performed via feature extraction based on artificial intelligence by MatLab R2013a for box counting algorithms. Otsu’s graythresh method by MatLab R2013a is applied to binarize the images. The results of proposed methodology are illustrated as log–log curves where the fractal dimensions are recognized by curve fitting (CF) tool with more than 95% accuracy. The outputs express that starch samples’ FD vary in the range from 1.636 to 1.926 among which the last is identified as non-defective polymer. Non-defective feature is of great importance for quality control measures and chemical reactivity being here highlighted as biodegradability.     

Polymer adsorption on a fractal substrate: numerical study

We study the adsorption of flexible polymer macromolecules on a percolation cluster, formed by a regular two-dimensional disordered lattice at critical concentration p(c) of attractive sites. The percolation cluster is characterized by a fractal dimension d(s) (p(c))=91/49. The conformational properties of polymer chains grafted to such a fractal substrate are studied by means of the pruned-enriched Rosenbluth method. We find estimates for the surface crossover exponent governing the scaling of the adsorption energy in the vicinity of transition point, φ(s)(p(c))=0.425±0.009, and for adsorption transition temperature, T(A)(p(c))=2.64±0.02. As expected, the adsorption is diminished when the fractal dimension of the substrate is smaller than that of a plain Euclidean surface. The universal size and shape characteristics of a typical spatial conformation which attains a polymer chain in the adsorbed state are analyzed as well.     

Permanent antistatic phthalocyanine/epoxy nanocomposites - Influence of crosslinking agent, solvent and processing temperature

Cross-linked epoxy matrices containing small amounts of semi-conductive phthalocyanine (Phthalcon) nanoparticles were prepared using different crosslinking agents and processing temperatures. A starting mixture containing an optimum dispersion of these nanoparticles and with an almost equal and large Hamaker constant was always used. Nevertheless large differences in the relation between the volume conductivity σ_v and the particle concentration φ were found and this relation appeared to be sensitive to small changes in processing temperature and the application of a post-cure. Also the amine crosslinker chosen and the initial amount of solvent (catalyst) in the starting dispersion had a major effect. It was shown that these changes influence strongly the formation of and the final conductive fractal particle network morphology through the polymer matrix. During processing a local relaxation of the initially formed fractal particle network into another fractal particle network was often observed, which introduced or enlarged the amount of isolating material between the particles of the conductive network and changed the fractality and structure of the conductive backbone of the particle network. This local relaxation lowered the σ_v at each phthalcon concentration and enlarged φ_c by several orders of magnitude. The occurrence of local relaxation is dependent on the rate of viscosity change during the crosslinking of the polymer matrix components, the way the fractal conductive particle network is formed during processing (universal or non-universal) and the amount of solvent present. Local relaxation may even occur after the gel point of the polymer matrix. A severe post-cure may be needed to stop this local relaxation. To our knowledge local relaxation of a (fractal) nanoparticle network in a polymer matrix during processing is a new phenomenon, not reported before for polymer composites containing (conductive) nanoparticles.     

Dissipative structures formed in the course of drying an aqueous solution of poly(allylamine hydrochloride) on a cover glass

Macroscopic and microscopic dissipative structural patterns formed in the course of drying a deionized aqueous solution of cationic polyelectrolyte, poly(allylamine hydrochloride) on a cover glass have been observed. Drying times range from 40 min at 45 °C to 450 min at 5 °C, and are insensitive to the polymer concentration. Pattern area shrinks toward the center at the low polymer concentrations, and increases as the concentration increases. A macroscopic broad ring pattern, where the polymer accumulates densely, forms in many cases. Beautiful fractal patterns are observed at the microscopic scale. The fractal dimension increases from 1.2 to 1.6 as polymer concentration increases from 10^-6 monoM to 10^-2 monoM. The relative rates between the water flow at the drying front and the convection flow of water accompanying the movement of polymer are important for the macroscopic and microscopic pattern formation.