高温固体氧化物燃料电池多孔电极结构介尺度研究方法

高温固体氧化物燃料电池（SOFC）在可持续新能源领域具有广泛的研究与应用前景,多孔电极结构的本质特征是介尺度,这种特性对电极内物质传输和电池性能起着决定性作用。本文综述了应用于多孔电极结构的微尺度和介尺度的数值、物理研究方法以及介尺度耦合其他尺度的多尺度方法,分别讨论了各方法适用的研究内容、研究进展及其优缺点。通过分析得出,微尺度方法可精确模拟SOFC电极材料的微观特性,介尺度方法可重构复杂的电极微观结构、模拟三相反应,同时是研究电极微观结构和宏观模拟之间的重要桥梁,因此,介尺度与其他尺度方法的耦合可以较好地解决微观结构和多物理场耦合下的相互作用。在未来的研究中,降低介尺度及其耦合的多尺度方法的计算成本、发展先进的实验设备和可视化技术具有重要的研究潜力与价值。     

PP/PA11共混物微、介观形态的分子模拟

采用分子动力学（MD）和介观动力学（MesoDyn）模拟方法研究了不同质量含量（10/90、30/70、50/50、70/30和90/10）PP/PA11共混物的相容性和介观形态结构。通过对MD模拟得到的Flory-Huggins相互作用参数（χ）和PP-PP、PA11-PA11及PP-PA11分子间C-C原子对径向分布函数的研究表明：当PP与PA含量为90/10时两者具有一定的相容性,而其它比例的相容性则较差。为了进一步研究共混物的介观形态结构,采用MesoDyn模拟方法在介观尺度对共混体系的介观形貌进行了研究,将通过MD模拟计算的分子间相互作用参数和其他结构参数（重复单元个数、聚合度和极限特征比等）转化为MesoDyn模拟的输入参数,实现了微、介观多尺度模拟的连接。     

分子模拟在高分子物理教学过程中的应用

高分子物理是研究高分子材料微观结构、运动模式、物理性能及它们相互之间关系的一门重要基础性科学。高分子材料微观结构和运动模式难以在实验上直接被观察到,较抽象,这使得学生难以理解。我们利用分子模拟方法直接从分子尺度展示高分子材料的微观聚集态结构的演变过程,使学生更容易理解高分子物理中的相关现象和理论。     

微流控乳液模板法构建功能微颗粒过程中介尺度结构定向调控的研究进展

功能微颗粒材料因其微型化和多功能化等优点而在诸多领域具有广泛的应用。微流控技术可控制备的多样化乳液液滴体系为功能微颗粒材料的创新设计与可控制备提供了优良而独特的模板。深入研究乳液模板法构建功能微颗粒材料过程中介尺度结构的形成与演变规律,以及液滴界面介尺度结构与乳液动力学行为、界面传质与反应耦合对微颗粒介尺度结构的影响规律等,对于实现乳液模板结构调控与新型功能微颗粒材料创新制备具有重要意义。本文主要综述了微流控乳液模板法构建功能微颗粒过程中介尺度结构定向调控的研究进展,着重涵盖了两方面内容：（1）微流控法可控制备乳液模板的过程中,液滴界面两亲分子聚集态介尺度结构的调控与液滴运动、吞并、融合、相界面定向演变等动力学行为之间的相互影响关系和调控机制,以及上述调控对液滴形貌、结构和组成的影响规律;（2）乳液模板制备功能微颗粒的过程中,界面传质、反应,及两者耦合对微颗粒介尺度结构的定向调控,以期为新型功能微颗粒材料的高效制备与性能强化提供科学指导。     

气液两相分离的免方程多尺度模拟方法

提出了一种用于模拟气液两相分离过程的免方程多尺度方法, 该方法以格子Boltzmann(LB)模型作为介观仿真器, LB模型进行少量演化步后运用二阶伸缩式投影方法对介观仿真器演化得到的结果进行有效的外推处理, 能够快速准确地获取后续演化步的结果, 从而实现对气液两相分离过程的多尺度模拟研究。对气液分离过程中饱和密度曲线和模型产生的伪速度大小的对比分析表明所提出的多尺度模拟方法能够快速准确地反映气液两相分离过程的宏观特性, 证明了所提方法的准确性和高效性。     

分子模拟在化学工程中的应用

总结了不同尺度分子模拟技术在化工中的发展现状,利用量化计算的方法,可以研究纳微尺度表界面的活性及其对催化反应的影响。采用分子动力学模拟可很方便地研究受限条件下流体行为,采用粗粒化模拟技术可研究介观结构。最后介绍了反应力场模拟这种涵盖反应和传递的模拟新方法。随着模拟理论和并行技术的进步,分子模拟的定量化程度越来越高,必将与化工应用的实验结果越来越有可比性,从而在化工生产和实践中担当更重要的角色。     

分子模拟在分子识别中的应用

随着计算机化学及量子化学理论的发展,其在化学、材料及生物医药等领域得到了广泛的应用。综述了分子模拟的方法:分子对接和分子动力学方法。着重介绍了分子动力学方法及其在分子识别领域的应用。分子对接方法是分子结构设计中的重要技术之一,可以预测生物分子复合物的结构和功能。分子动力学模拟可以使我们从原子尺度理解并预测物质的宏观性质,从而精确预测真实系统的物理性质。     

从多尺度到介尺度——复杂化工过程模拟的新挑战

化工过程普遍面对具有多尺度结构的复杂系统,而作为从基本单元相互作用形成系统整体行为与功能的关键环节,介尺度结构对化工过程的定量描述和定向调控具有重要意义。同时,化学、材料、生物、物理和系统科学等领域也都逐步认识到各自的介尺度问题及其共同特性。这表明对介尺度结构与行为共性的深入研究将对科学界产生全局性的影响,同时也表明这样的研究必须通过多学科充分交流、紧密合作才能取得重大进展。本文试图从多尺度研究的背景出发探讨化工及相关过程中介尺度模拟的意义、挑战和方法,并展望其发展。     

SBA-15介观相形成过程的耗散粒子动力学模拟

采用耗散粒子动力学方法（dissipative particle dynamics,DPD）,以介孔分子筛SBA-15的合成原料P123/TEOS/H₂O为研究体系,模拟了P123/TEOS超分子自组装行为,及剪切力作用下介孔分子筛SBA-15六角介观相的形成过程。结果表明：在水溶液中,P123与TEOS两相能够发生协同作用自组装形成超分子聚集体（胶束）,该胶束由疏水的PPO球核、亲水的PEO球壳以及聚集包裹在P123外部的TEOS组成;引入稳恒剪切力后,P123/TEOS超分子聚集体则会逐渐转变成规整的六角结构,并最终形成SBA-15六角介观相,这与实际材料的TEM电镜图片相吻合。可以说,DPD模拟方法是一个研究有序介孔分子筛SBA-15形成机理的有效手段,可为实验合成提供介观层面上的重要信息。此外,还拓展了DPD模拟在超分子自组装介观尺度研究方面的新应用。     

蛋白质体系分子动力学模拟的前沿进展-从介科学角度重新审视

蛋白质是生命的物质基础,是生命活动的主要承担者,对蛋白质时空多尺度结构及其控制机制的深入理解是探索生命起源、病理认知及新药开发的基础. 受实验表征手段及时空分辨率的限制,计算机模拟已成为研究蛋白质体系结构及功能的重要手段之一. 由于蛋白质体系模拟所涉及的时间和空间跨度均相当大,因此,准确且快速地描述其时空多尺度结构,从而分析体系的控制机制及相关生理过程,成为分子动力学模拟面临的巨大挑战. 本工作对近半个世纪以来的分子模拟方法,特别是分子动力学方法和相关的增强采样技术在蛋白质体系研究中的应用进行了总结,综述了近年来分子动力学的理论模型和算法的发展,并介绍了这些方法在结构化蛋白质的天然结构与构象变化、固有无序蛋白质的动态结构及其结合底物的动力学过程及分子机理、分子伴侣及病毒等蛋白质复合物体系中的研究成果;汇总了高性能计算的飞速发展所带动的分子动力学模拟软件的变革,拓展了蛋白质模拟的时空尺度,重点阐述了大规模高性能分子动力学模拟在蛋白质研究中的应用;最后,基于介科学理论的飞速发展及其在多种复杂体系的成功运用,对未来蛋白质体系的模拟方法和理论研究的趋势进行了思考和展望.     

立构嵌段聚丁二烯的研制Ⅳ．立构二嵌段与三嵌段共混聚丁二烯的研究

在以ｎ－Ｂｕｌｉ为引发剂，环己烷为溶剂，二哌啶乙烷和二乙基锌为调节剂的丁二烯负离子聚合过程中，采用高分子设计，分别以二甲基二氯硅烷、苯甲酸乙酯和乙酸乙酯为偶联剂，合成了不同分子量、不同嵌段比及共混比的１，４－１，２／１，４－１，２－１，４及１，２－１，４／１，２－１，４－１，２立构嵌段聚丁二烯（ＰＢ），考察了共混物的微观相分离、流变性及屈服强度。结果表明，嵌段共混ＰＢ的分子量、嵌段比、共混比值只有在一定范围时，共混物才产生微观相分离，分相的嵌段共混ＰＢ具有较好的流变性、加工性，较小的冷流性和较高的屈服强度。     

Photoresponsive liquid crystalline block copolymers: From photonics to nanotechnology

Being one of the most fascinating multi-functional materials, photoresponsive liquid crystalline block copolymers (PLCBCs) have attracted much attention because of their light controllable properties of supramolecularly self-assembled structures. These originate from their unique features combining the advanced function of photoresponsive liquid crystalline polymers (PLCPs) with the inherent property of microphase separation of block copolymers (BCs). Benefiting from recent progresses in materials chemistry, diverse PLCBCs have been designed and synthesized by controlled polymerization using different synthetic routes and strategies. Generally, PLCBCs show different performance depending on their self-organization and molecular composition, with the PLCP blocks in the minority phase or in the majority phase. One of the most important properties of PLCBCs is supramolecular cooperative motion, resulted from the interactions between liquid crystalline elastic deformation and microphase separation, which enables them to self-assemble into regularly ordered nanostructures in bulk films with high reliability. These nanostructures contribute to improving the optical performance of polymer films by eliminating the scattering of visible light, in favor of their photonic applications. With the help of liquid crystal alignment techniques, both parallel and perpendicular patterning of nanostructures has been fabricated in macroscopic scale with excellent reproducibility and mass production, which provides nanotemplates and nanofabrication processes for preparing varieties of nanomaterials. Recent findings about PLCBCs including their synthesis, diagram of microphase separation, structure-property relationship, precise control of nanostructure as well as their applications in photonics to nanotechnology are reviewed.     

聚氨酯的结构与微相分离

介绍了聚氨酯的组成,结构及微相分离特性,综述了软段的种类,质量分数,相对分子质量,以及硬段的组成,结构,质量分数对聚氨酯微相分离程度的影响,聚氨酯的微相分离是一个松驰过程,不仅与热力学因素有关,而且也受动力学过程的影响。     

A Review of Computational Methods in Materials Science: Examples from Shock-Wave and Polymer Physics

This review discusses several computational methods used on different length and time scales for the simulation of material behavior. First, the importance of physical modeling and its relation to computer simulation on multiscales is discussed. Then, computational methods used on different scales are shortly reviewed, before we focus on the molecular dynamics (MD) method. Here we survey in a tutorial-like fashion some key issues including several MD optimization techniques. Thereafter, computational examples for the capabilities of numerical simulations in materials research are discussed. We focus on recent results of shock wave simulations of a solid which are based on two different modeling approaches and we discuss their respective assets and drawbacks with a view to their application on multiscales. Then, the prospects of computer simulations on the molecular length scale using coarse-grained MD methods are covered by means of examples pertaining to complex topological polymer structures including star-polymers, biomacromolecules such as polyelectrolytes and polymers with intrinsic stiffness. This review ends by highlighting new emerging interdisciplinary applications of computational methods in the field of medical engineering where the application of concepts of polymer physics and of shock waves to biological systems holds a lot of promise for improving medical applications such as extracorporeal shock wave lithotripsy or tumor treatment.     

Computer simulation and molecular theory of self-organization and mechanical properties of polymers

In this contribution, we report on a study of the self-organization of extended linear polymer chains into condensed globules using molecular dynamics methods. We have found that condensed chains (globules) are amorphous or crystalline depending on the interaction potential between constituents. Any structure is formed in several stages. The structures obtained were used in further computer simulations to investigate such processes as compression, decompression, fracture, and flow. We have found that there are different types of fracture and plastic behavior with their own energy, fluctuation, and defect characteristics. On the basis of the computer simulation results obtained, the equation of motion is derived for the system of chain macromolecules slipping relative to each other. The equation takes into account the relaxation and friction in the system. The solution obtained gives the general law that connects stress, strain rate, molecular mass, potential relief, and temperature. It also gives sound physical grounds for some empirical relations that are used in polymer technology.     

Gel-size dependence of temperature-induced microphase separation in weakly-charged polymer gels

The gel-size dependence of microphase separation in weakly-charged gels of N-isopropylacrylamide (NIPA) and 1-vinylimidazole (VI) copolymers has been investigated using swelling measurement, small-angle neutron scattering (SANS), and dynamic and static light scattering (DLS/SLS). It is known that weakly-charged polymer gels undergo microphase separation in a poor solvent as a result of competing interactions involving hydrophobic attraction versus electrostatic repulsion. The microphase separation is characterized by a scattering maximum in SANS intensity functions of which Bragg spacing, Λ, is around 20-30 nm. However, when gel size was reduced to the order of Λ, no microphase separation was observed. Instead, a typical scattering of isolated spherical particles was clearly observed. On the basis of the experimental evidence, we conclude that microphase separation has its own wavelength independent of gel size, and nanometer-order gels, i.e., nanogels, do not undergo microphase separation.     

Processing temperature dependent mechanical response of a thermoplastic elastomer with low hard segment

The mechanical responses including monotonic and cyclic tensile responses have been investigated on a microphase-separated poly (styrene-isoprene-styrene) triblock copolymer (SIS). The specimens were injection-molded by using different melt temperatures to acquire different microphase structures. As a result of temperature-dependent segregation driving force, the specimens with reduced microphase separation can be obtained by increasing processing melt temperature from 180 °C to 240 °C. On the basis of stress-strain behavior, Young's modulus was found to increase with increasing PS domain continuity in the order of disorder state to disordered spheres to body-cubic-centered (BCC) spheres to oriented cylinders morphology. Meanwhile, cyclic hysteresis decreases with reduced microphase separation and with decreasing the applied predetermined maximum tensile strain. In addition, the Mooney–Rivlin phenomenological approach was used to evaluate and explore the relationship between the polymer topological networks and the rubber elasticity of thermoplastic elastomers.     

Control of the hierarchical structure of polymer articles via “structuring” processing

Every day, numerous polymer materials are fabricated into specific articles with definite sizes, shapes and forms using polymer processing. Obviously, polymer processing has become one of the most active areas of polymer science and engineering. The key is to profoundly explore the processing-structure-performance relations for various polymer-based materials. From a structure-dominated performance point of view, the ultimate physical/chemical properties of polymer articles are directly related to their internal multiscale (hierarchical) structures, which range from the molecular, nanometer, submicron and micron scale to the mesoscopic level. Because the features of hierarchical structures strongly depend on the external fields that are imposed during processing, many structural items, such as the chain configuration, crystalline polymorphism, orientation and phase separation behavior, can be well or precisely controlled, resulting in significant variations in the hierarchical structure. Due to developments in mechanical techniques, various external fields, such as thermal, shear, extension, ultrasonic, electronic, magnetic and super-critical fluid fields, may be introduced into polymer processing, leading to significant improvements in the tailoring of the microstructure/morphology via processing. This process is characterized by an “externally applied field determined hierarchical structure”, i.e., a “structuring” processing, which represents an advanced trend in modern polymer processing and is the topic of this review. This contribution includes the following: (1) an introduction, (2) the in situ monitoring of polymer processing, (3) progress in “structuring” processing and (4) concluding remarks and perspectives.