“高分子物理学”中的基本概念

"高分子物理学"具有基本概念多、理论多的特点,本文沿着"高分子物理学"的主线,按照"聚合物结构-分子运动-性能"的基本框架,从聚合物的链结构、聚合物的凝聚态结构、高分子溶液、黏弹性、聚合物的分子运动和转变、聚合物的极限力学性质等方面,阐明所涉及的重要基本概念的含义和作用,目的是使学生在明晰基本概念的基础上,掌握"高分子物理学"中的公式和基础理论,系统整体化学习高分子物理这门基础理论课程。     

高分子凝聚态结构与化学

高分子凝聚态的研究是高分子科学中的重要内容,在高分子凝聚态的形成机制及对宏观物理性能的影响方面已形成了较为系统的理论和应用实践基础,但在高分子凝聚态的化学性质方面虽有较多的研究工作,却鲜有系统性的归纳总结。凝聚态化学概念的提出,有助于科研人员更深入、系统地研究高分子聚集态结构与其化学性质之间的关系及相关规律。本文以高分子凝聚态为讨论对象,对高分子凝聚态化学性质的一些代表性研究工作进行了归纳和整理,内容包括:(1)高分子结构化学对高分子凝聚态的影响;(2)高分子凝聚态结构对进一步化学反应的影响;(3)高层级凝聚态的化学性质及其对化学反应的影响。希望通过对上述研究工作的实例分析和探讨,为科研人员从化学性质变化的角度去理解和开展高分子凝聚态的研究提供一些参考和启示。     

强熵效应与大分子体系的熵调控

在大分子体系中,以链的构象熵为主的熵效应对体系的微观结构和宏观性能都起着至关重要的作用.然而,熵的统计本质使其远不像焓作用那么直观,甚至会导致反直觉的现象出现.因此,探寻大分子体系中的熵效应,对于深入揭示此类体系纷繁复杂现象背后物理机制的重要性来说是不言而喻的,已成为高分子与软凝聚态物理学以及生命科学等多学科相交叉的重要前沿研究领域.如何在阐释熵效应的独特作用规律基础上,有效地调控熵以实现对体系微观结构的熵调控进而发展新型功能体系,是该领域一个亟需解决的重要科学问题.本文总结了我们在提出并发展熵调控策略方面的研究进展.首先,剖析了熵效应的一些基本作用规律,涵盖熵致有序和熵力等,并进一步提出了强熵效应的概念.其次,阐述了熵调控策略的必要性、基本原理以及调控途径.同时,举例介绍了熵调控策略在大分子体系中的应用,涵盖高分子纳米复合体系、凝胶网络、生命大分子体系以及大分子胶体体系等.最后,简明扼要地展望了该领域的未来发展趋势以及面临的关键问题,以期为其以后的发展提供些许有益的启迪.     

高分子单链凝聚态与线团相互穿透的多链凝聚态

高分子单链凝聚态由于链内链结构单元间存在范德华吸引作用,高分子链呈打圈链构象,而多链凝聚态由于链内链单元间的吸引作用被与相互穿透的近邻链的单元间吸引作用所屏蔽,高分子链呈高斯链构象.本文简要介绍单链凝聚态试样的制备方法,单链单晶体、单链玻璃体、溶胀的单链高弹态拉伸等的实验观察,并提出从单链凝聚态到多链凝聚态的转变过程问题,即高分子线团的相互穿透过程,目前还缺少基础了解.     

我国国家科学基金化学科学重大项目简介

高分子凝聚态的基本物理问题研究——项目简介之六高分子材料是国民经济、国防尖端迫切需要的重要材料.世界年产量已达亿吨.在美国有近半数的化学家从事与高分子有关的研究工作.为进一步促进我国高分子材料工业的发展,有必要加强相应的基础研究. 高分子凝聚态具有多层次结构、多重分子运动和非平衡等特点.通过化学与物理学科的交     

溶致性液晶高分子PBT的结构表征

聚苯撑苯并二噻唑(PBT)具有典型的溶致性液晶行为,聚合后期有液晶态搅拌乳光现象。偏光显微镜观察到具有向列型织态结构,溶液粘度随浓度变化,当进入液晶区时有明显的反常突变。对高分子链和凝聚态结构进行了X射线衍射研究,测定了晶胞参数、C轴等同周期和高分子链的取向度,并表明取向的PBT凝聚态是由刚性棒状的分子呈园柱体形态二维有序堆砌而成的。     

溶剂性能对部分解缠结聚氯乙烯有序结构形成的影响

一般的高分子非晶态是线团相互穿透的多链凝聚态,是分子固体中非常独特的一种分子凝聚态[1～4].而高分子链的缠结是高聚物凝聚态的重要特征之一.缠结是指高分子链之间形成物理交联点,构成网络结构,使分子链的运动受到周围分子的羁绊和限制[5],因此缠结对链的构象调整以及链单元     

高分子凝聚态的若干基本物理问题研究

本项目在高分子凝聚态的研究中取得了许多重要成果,并提出了若干新概念。主要创新点有高分子单链凝聚态（单链玻璃态和单链单晶）、高分子链的凝聚缠结、分子链大尺度高度取向而小尺度无规取向的非晶态、动态接触浓度C8、固化诱发条带织构等。     

聚丙烯锂离子电池隔膜制备技术在《高分子物理》课程的案例教学

干法单向拉伸制备聚丙烯锂离子电池隔膜技术涉及《高分子物理》课程中高分子的链结构、凝聚态结构、分子运动和转变、粘弹性、屈服和断裂、流变性、表面和界面等章节的内容,非常适合作为教学案例.本文探讨如何将生产过程涉及的高分子物理知识点与课程教学相结合进行案例教学,重点分析每步工序对应的聚丙烯凝聚态结构和工艺参数变化对结构及性能...     

高分子单链凝聚成与线团相互穿透的多链凝聚态

高分子单链凝聚态由于链内链结构单元间存在范德化吸引作用,高分子链呈打圈链构象,而多链凝聚态由于链内链单元间的吸引作用被与相互穿透的近邻链的单元间吸引作用所屏蔽,高分子链呈高斯链构象。本文简要介绍单链凝聚态试样的制备方法,单链单晶体、单链玻璃体、溶胀的单链高弹态拉伸等的实验观察,并提出从单链凝聚态到多链凝聚态的转变过程问题,即高分子线团的相互穿透过程,目前还缺少基础了解。     

Sources synchrotrons au Japon: perspectives

Synchrotron radiation has become a unique tool for probing the structure of matter. It has a broad range of applications, not only in basic science (molecular and atomic physics, condensed matter physics, earth science, materials science, chemistry, molecular and cell biology, surface and interface physics, etc.) but also in medicine and in the industry (material investigation, lithography, micro-machining, drug design, etc.).With one third of the world sources, Japan leads the G-8 countries and is also the leader when it comes to “industrial sources”. Japan is not building synchrotron sources solely to support basic research, it is building them because of the diversity, importance, and potential of high-technology, industrial applications of synchrotron radiation. Each source is an investment for the future, opening new research areas and calling for technical innovations.The purpose of this paper is to offer an overview of the Japanese synchrotron radiation sources and their research activities. A special attention will be given to the development of industrial sources, as well as the application of synchrotron radiation to materials science.     

Radioactive Beams: A Probe for Atoms and Nuclei

A brief summary of the new technical developments of producing intense, energetic radioactive heavy ion beams is provided with some insight of what is happening in the area of nuclear science. These developments have revitalized the entire field of nuclear chemistry and physics, and have provided useful probes for such areas as nuclear astrophysics and condensed matter physics. These are also applications of these new beams in the areas of nuclear medicine and radiopharmacology that have not been mentioned. In many ways, with the start of the next millennium, it is clear that the study of the nucleus is still as important area of research as it was at the start of this century. There are important questions that need to be answered and these new probes represents a first step towards finally addressing these questions in a meaningful fashion.     

Effect and Mechanism of Solvent Properties on Solution Behavior and Films Condensed State Structure for the Semi-rigid Conjugated Polymers

Solvents have an essential association with polymer solution behavior. However, few researches have been deeply done on this respect. In recent years, our research group focus on the study on effect of solvent properties on solution behavior and film condensed state structure for semi-rigid conjugated polymer up till to apply for optoelectronic device. Herein, influence of solvent properties including solubility of solvent, aromaticity, polarity and hydrogen bonds on semi-rigid polymer chain solution behavior, i.e., single chain conformation, chain shape,size and chains aggregated density were studied by means of static/dynamic laser light scattering(DLS/SLS) and exponential law etc. Effect of solvent properties on condensed state structure of the semi-rigid conjugated polymer film was studied by UV absorption spectroscopy, PL spectroscopy and electron microscopy etc. The essential reasons for the influence were discovered and the mechanism was revealed. It was found that solution behavior with different solvent properties had an essential physical relationship with chains condensed state structure of the semi-rigid conjugated polymers. More importantly, there was a quantitative structure-activity relationship between solution and film. The key to this relationship depended on the interaction between solvent molecules and the semi-rigid conjugated polymer chains. This interaction could also affect optoelectronic devices performance. This study is of great significance to effectively control the condensed state structure of the semirigid conjugated polymers in the process of dynamic evolution from solutions to films. It not only enriches the knowledge and understanding of both semi-rigid conjugated polymer solution behaviors and film condensed state physics based on polymer physics, but also is meaningful to practical application for conjugated polymer and other traditional polymer systems.     

Light scattering near and from interfaces using evanescent wave and ellipsometric light scattering

The broad range of interface light scattering investigations in recent years shows the power and the versatility of these techniques to address new and open questions in colloid and interface science and the soft condensed matter field. Structural information for polymers, liquid crystals, or colloids close to planar or spherical colloidal interfaces are either captured with long range light scattering resolution, or in a complementary approach by high resolution ellipsometric techniques. Of special interest is the dynamic behavior close to or in interfaces, since it determines material properties and responses to external fields. Due to the broad dynamical range and the high scattering contrast for visible light, interface light scattering is a key to elucidate soft matter interfacial dynamics. This contribution reviews experimental and related theoretical approaches for interface light scattering and further gives an overview of achievements based on such techniques.     

Chemically specific coarse-graining of polymers: Methods and prospects

Coarse-grained (CG) modeling is an invaluable tool for the study of polymers and other soft matter systems due to the span of spatiotemporal scales that typify their physics and behavior. Given continuing advancements in experimental synthesis and characterization of such systems, there is ever greater need to leverage and expand CG capabilities to simulate diverse soft matter systems with chemical specificity. In this review, we discuss essential modeling techniques, bottom-up coarse-graining methodologies, and outstanding challenges for the chemically specific CG modeling of polymer-based systems. This methodologically oriented discussion is complemented by representative literature examples for polymer simulation; we also offer some advisory practical considerations that should be useful for new researchers. Given its growing importance in the modeling and polymer science community, we further highlight some recent applications of machine learning that enhance CG modeling strategies. Overall, this review provides comprehensive discussion of methods and prospects for the chemically specific coarse-graining of polymers.     

晶态非极性聚合物内聚能密度的估算

有关凝聚态结构对聚合物内聚能密度的影响,在高分子物理学界一直未被关注。本文首次提出了利用结晶熔融热估算晶态非极性聚合物内聚能密度的方法,并对结晶态的聚四氟乙烯、聚乙烯和聚丙烯的内聚能密度进行了估算。估算值较好地解释了上述聚合物用作塑料但内聚能密度较小的理由。结晶熔融热本质上反映了非极性聚合物的晶态与非晶态分子间色散力相...     

Fractals and Related Hierarchical Models in Polymer Science

Polymer science, an interdisciplinary science well-rooted in organic chemistry and in materials science, encompasses an inordinate number and diversity of substance classes and thus has far-reaching applications. Interestingly, polymers also represent a great challenge to the theoreticians, since their theoretical treatment often necessitates appropriate extensions of the classical methods from solid state physics and from statistical physics. Thus, new concepts often have to be invoked when considering the special properties of polymers. In this review we concentrate on one of the modern concepts in the theory of polymers, namely on scaling. Scaling is closely associated with new developments in the field of fractals and of hierarchical structures. Such concepts are invaluable for the modeling of complex geometries and for describing dynamical processes in polymeric materials. Here, we focus on a presentation of these ideas and we outline examples of recent research in which these concepts have been successfully applied.     

石英晶体微天平在高分子科学中的应用

固/液界面上高分子的行为直接影响着界面的物理和化学性质.对于高分子在界面的动态行为,由于缺乏有效的手段,检测一直十分困难.最近,一种频率-耗散联用型石英晶体微天平(QCM-D)问世,它能够同时检测固/液界面上有关高分子质量和结构的变化,因而可应用于界面高分子研究的多个方面.本文介绍石英晶体微天平的基本原理,并综述作者实验室最近几年利用QCM-D开展的若干工作,包括固/液界面上高分子链的构象变化,固/液界面上高分子的吸附,高分子降解动力学和聚电解质的"层层组装"等方面.     

跟踪高分子学科发展前沿，建设高分子物理国家精品课程

为建设高分子物理精品课程,近年来我们关注和跟踪高分子科学发展前沿,开设了"高分子材料流变学"、"高分子凝聚态物理"等新课,编著出版新教材。这些课程和教材的一个显著特点是不失时机地将学科发展的新动态、新成果引入研究生、本科生教学,提升高分子物理课教学质量。在编著新教材中,除介绍大量新知识、新思想外,还探索性地构建起新课程的理论体系和框架。     

Experimental studies of the electronic structure of graphene

Graphene, the single layer of hexagonally coordinated carbon, is a two-dimensional material with many unusual properties; its physical realization a few years ago has caused a storm of activities in the solid state physics and materials science communities. The intriguing “massless Dirac Fermion” character of its charge carriers renders graphene a unique study object in condensed matter physics, and we discuss how surface-related techniques such as photoemission, STM and LEED play a prominent role in these investigations. We report on experimental studies of the growth and electronic structure of epitaxial single and few layer graphene on silicon carbide. The unusual band structure of single layer graphene and its evolution as layers are added towards bulk graphite is studied. In the special case of the bilayer, the opening of a gap by inducing an asymmetry through the influence of doping is examined. Finally, the influence of many body processes on the spectral function is discussed on the basis of high resolution photoemission data. The discussion of these aspects gives a comprehensive overview of the electronic structure of graphene as examined by experiment.