影响离子导电高分子材料性能的内因与外因

材料分子设计离不开结构与性能的关系。分析内因与外因两方面影响因素对材料功能特性的影响有助于优化功能材料的结构。本文以离子型导电功能高分子材料为例,详细分析了各种因素对材料电导率的影响,为离子型导电功能高分子材料的结构设计提供依据。     

《功能高分子材料》课堂教学方法的探索

功能高分子材料课堂教学过程涉及到大量高分子化学与高分子物理的基础知识,具有相辅相成的关系。在教学中如果能将高分子化学与物理知识与功能高分子材料的核心问题即"分子设计、结构与性能的关系",巧妙地衔接,紧密地结合,并有效地加以利用,不仅可以提高学生对该课程的重视度与学习兴趣,还可以加强教学效果,提升学生对专业知识的深层次理解与综合运用能力。本文结合这几年的教学实践,就如何利用功能高分子材料与高分子化学、高分子物理之间的联系以及后者对前者的辅助教学作用进行了阐述。     

试论高聚物结构与性能关系的三个层次

高分子物理的基本任务之一就是探求高聚物的结构与性能,揭示结构与性能之间的内在联系及其基本规律。高聚物结构与性能的关系应该包含3个层次:通过分子运动联系的"分子结构与材料性能"关系、通过产品设计联系的"凝聚态结构与制品性能"关系和通过凝聚态物理知识联系的"电子态结构与材料功能"关系。传统教材上仅讲授"结构与性能关系",有相当的局限性,需要在研究生阶段补充有关"凝聚态结构与制品性能"关系和"电子态结构与材料功能"关系的课程。     

高分子材料支化结构与流变性的联系串讲北大核心CSCD

高分子链结构为直链型或支化型以及高分子支链的形态、多寡和长度对材料的剪切黏度、黏流活化能、熔体破裂现象等流变性能有显著影响,且与高分子材料成型加工行为密不可分。本文以串讲方式讨论了高分子材料支化结构与流变性能之间的联系。理解、串并、归纳和总结高分子支化结构与流变性之间的联系有利于使学生更加深刻领会《聚合物流变学》课程中高分子材料结构与性能间的关系,串联高分子物理、聚合物流变学、高分子材料成型加工系列专业课程知识。     

高分子材料支化结构与流变性的联系串讲

高分子链结构为直链型或支化型以及高分子支链的形态、多寡和长度对材料的剪切黏度、黏流活化能、熔体破裂现象等流变性能有显著影响,且与高分子材料成型加工行为密不可分。本文以串讲方式讨论了高分子材料支化结构与流变性能之间的联系。理解、串并、归纳和总结高分子支化结构与流变性之间的联系有利于使学生更加深刻领会《聚合物流变学》课程中高分子材料结构与性能间的关系,串联高分子物理、聚合物流变学、高分子材料成型加工系列专业课程知识。     

形状记忆的聚乳酸/聚碳酸亚丙酯共混材料的结构与性能——针对《高分子物理》理论教学难点的综合性实验设计

“结构、性能及分子运动”三者之间制约关系是高分子物理的核心内容,其中“分子运动”的知识最为抽象,是学生学习的难点内容。针对此问题,融入教师科研成果,设计了“形状记忆的聚乳酸/聚碳酸亚丙酯共混材料的结构与性能”综合实验。通过该实验,学生系统而具体的理解“结构与分子运动”、“分子运动与力学性能”、“分子运动与形状记忆功能”的知识,掌握热分析、扫描电镜、力学性能以及形状记忆功能的实验技术,体会高分子基础理论在创造新材料中的典型应用。     

渗透汽化膜表面化学结构设计研究

综述了近年来渗透汽化膜表面结构设计调控的研究进展。膜表面结构的设计与优化是提高其分离性能的重要方法。然而高分子表面具有环境响应性,这往往导致高分子材料在使用环境中失去在表面设计时所期待的性能。因此,高分子膜表面的环境响应性是在对膜表面进行设计和调控过程中必须考虑的因素。本文介绍了渗透汽化膜表面结构设计的方法,重点阐述了高分子膜表面环境响应特性对膜表面性质以及渗透汽化性能的影响。指出了利用高分子膜的表面重构行为可以对其表面结构进行优化,从而有效地提高膜的分离选择性。     

高分子物理本科教学之我见

高分子物理是一门物理课,其内涵为高分子物质的结构、结构演变与各层次结构单元的运动规律,而非聚合物的"结构与性能"关系.这门课为解释结构与性能关系提供基础概念与理论,但不是"结构与性能"关系本身.这样的定位决定了高分子物理课不应采用系统教学法,而应当采用逻辑教学法,即从一个不证自明的公理(逻辑起点)出发,沿着一条主线,依次导出、建立全部理论体系.在高分子物理中,这个逻辑起点就是长链结构,主线就是熵弹性.故该门课程应按熵弹性这条主线展开.对现行高分子物理课程内容进行分析,大多数内容均可用熵弹性的主线串起来,另外少部分内容也与熵弹性有密切关系.应根据这两点对现行课程体系与教学方法进行改造,为课程各项内容之间建立逻辑关系,方便学生的学习与应用.     

从高分子运动的温度依赖关系看高分子运动特点

高分子的运动是高分子科学中最为基本、最为重要的问题之一,也是教学的重点之一,它是联系高分子微观结构与高聚物宏观性能之间的桥梁,本文就高分子运动的特点尤其是高分子运动的温度依赖关系进行了讨论,进而从本质上理解高聚物结构与性能之间的关系.     

基于“基础促进创新，实践推动科研”的《材料结构与性能》课程教学改革探索与实践

《材料结构与性能》是一门研究高分子的多层次结构、分子运动和物理机械性能之间的课程。结合《材料结构与性能》课程的特点,本文分析了《材料结构与性能》课程的现状和存在的问题,提出了“基础促进创新,实践推动科研”的教学改革思路,即从思维导图、理论教学与实验教学相融合角度,实现抽象高分子物理理论的具象化,夯实基础;依据国家重大需求和实际应用案例,通过主题讨论翻转课堂,提高学生批判和质疑思维,分析和解决问题能力,为高分子材料的创新性学术研究提供指导。     

Electronic Properties of Vinylene-Linked Heterocyclic Conducting Polymers: Predictive Design and Rational Guidance from DFT Calculations

The band structure and electronic properties in a series of vinylene-linked heterocyclic conducting polymers are investigated using density functional theory (DFT). In order to accurately calculate electronic band gaps, we utilize hybrid functionals with fully periodic boundary conditions to understand the effect of chemical functionalization on the electronic structure of these materials. The use of predictive first-principles calculations coupled with simple chemical arguments highlights the critical role that aromaticity plays in obtaining a low band gap polymer. Contrary to some approaches which erroneously attempt to lower the band gap by increasing the aromaticity of the polymer backbone, we show that being aromatic (or quinoidal) in itself does not ensure a low band gap. Rather, an iterative approach which destabilizes the ground state of the parent polymer toward the aromatic ? quinoidal level crossing on the potential energy surface is a more effective way of lowering the band gap in these conjugated systems. Our results highlight the use of predictive calculations guided by rational chemical intuition for designing low band gap polymers in photovoltaic materials.     

Threading Chalcogenide Layers with Polymer Chains

Inserting polymers into a crystalline inorganic matrix to understand the structure, position, and the structure–property relationships of the resulting composites is important for designing new inorganic‐organic materials and tuning their properties. Single crystals of polymer‐chalcogenide composites were successfully prepared by trapping polyethyleneglycol within a selenidostannate matrix under surfactant‐thermal conditions. This work might provide a new strategy for preparing novel crystalline polymer‐inorganic composites through encapsulating polymer chains within inorganic matrices.     

C−H Functionalization of Commodity Polymers

Synthetic manipulation of polymer substrates is one of the oldest and most reliable methods to increase the functional diversity of soft materials. Modifying the chemical structure of polymers that are already produced on a commodity scale leverages the current high‐volume and low‐cost production of commodity plastics for the discovery of modern materials. A myriad of polymer C?H functionalization methods have been developed which enable the modification of material properties on both a laboratory and industrial scale. More recently, driven by advances in C?H activation, photoredox catalysis, and radical chemistry, chemoselective approaches have emerged as a means to impart precise functionality onto commodity polymer substrates. This Review discusses the historical significance of and contemporary advances in the C?H functionalization of commodity polymers. The conceptual approach outlined herein presents exciting new directions for the field, including increasing the value of otherwise pervasive materials, uncovering entirely new material properties, and a viable path to upcycle post‐consumer plastic waste.     

Controlled polymerization in mesoporous silica toward the design of organic-inorganic composite nanoporous materials

Free-radical polymerization inside mesoporous silica has been investigated in order to open a route to functional polymer-silica composite materials with well-defined mesoporosity. Various vinyl monomers, such as styrene, chloromethyl styrene, 2-hydroxyethyl methacrylate, and methacrylic acid, were polymerized after impregnation into mesoporous silicas with various structures, which were synthesized using polyalkylene oxide-type block copolymers. The location of the polymers was systematically controlled with detailed structures of the silica framework and the polymerization conditions. Particularly noteworthy is the polymer-silica composite structure obtained by in situ polymerization after the selective adsorption of monomers as a uniform film on silica walls. The analysis of XRD data and the N(2) adsorption isotherms indicates the formation of uniform polymer nanocoating. The resultant polymer-silica composite materials can easily be post-functionalized to incorporate diverse functional groups in high density, due to the open porous structure allowing facile access for the chemical reagent. The fundamental characteristics of the composite materials are substantiated by testing the biomolecule's adsorption capacity and catalytic reactivity. Depending on the structure and composition of polymers, the resultant polymer-silica composite materials exhibit notably distinct adsorption properties toward biomolecules, such as proteins. Furthermore, it is demonstrated that the nanocoatings of polymers deposited on the mesopore walls have remarkably enhanced catalytic activity and selectivity, as compared to that of bulk polymer resins. We believe that, due to facile functionalization and attractive textural properties, the mesoporous polymer-silica composite materials are very useful for applications, such as adsorption, separation, host-guest complexes, and catalysis.     

Design and synthesis of interpenetrating polymer networks for second-order nonlinear optics

There has been a tremendous recent interest in the development of second-order nonlinear optical (NLO) polymeric materials for photonic applications. However, a major drawback of second-order NLO polymers that prevents them from being used in device applications is the instability of their electric field induced dipolar alignment. The randomization of the dipole orientation leads to the decay of second-order optical nonlinearities. Numerous efforts have been made to increase the stability of the second-order NLO properties of polymers. The search for new approaches to develop NLO polymers with optimal properties has been an active research area since the past decade. A novel approach, combining the hybrid properties of high glass transition temperatures, extensively extensively crosslinked networks and permanent entanglements, based on interpenetrating polymer networks (IPN) is introduced to develop stable second-order NLO materials. Two types of IPN systems are prepared and their properties are investigated. The designing criteria and the rationale for the selection of polymers are discussed. The IPN samples show excellent temporal stability at elevated temperatures. Long-term stability of the optical nonlinearity at 100°C has been observed in these materials. Temporal stability of the NLO properties of these IPNs is synergistically enhanced. Relaxation behavior of the optical nonlinearity of an IPN system has been studied and compared with that of a typical guest/host system. The improved temporal stability of the second-order NLO properties of this IPN system is a result of the combination of the high rigidity of the polymer backbones, crosslinked matrices and permanent entanglements of the polymer networks. A slight modification of the chemical structure resulted in an improvement of the optical quality of the sample.     

Metal-Catalyzed Coupling Reactions In The Synthesis Of New Conducting Polymers

The use of transition metal-catalyzed coupling reactions in the synthesis of conducting polymers is discussed. These reactions are of growing importance in polymer synthesis and are particularly important in the synthesis of highly functionalized conjugated (conducting) polymers. In this report we discuss applications of this methodology for the synthesis of conducting polymer sensory materials and polymers with reactive functional groups. In the sensory polymers we have incorporated crown ether groups which induce perturbations to the polymer's electronic structure when exposed to an alkali metal ion. Our interest in polymers with reactive functional groups is for the development of polymers which can be transformed into novel all-carbon ladder polymers.     

高分子结构与性能关系原理-结构层次的意义

高分子结构是高分子性能的重要物质基础,对其结构进行合理的划分,有助于准确把握高分子物理知识体系的内在脉络。高分子结构层次的划分不仅要思考静态时特定质点在空间的堆砌特征,而且也要考虑结构出现运动或是变化的基本单元。按照质点尺度的不同,高聚物的结构可以分为单一高分子结构(链结构)、多个高分子结构(凝聚结构)和多种高分子结构(织态结构)三个主要层次。其中,化学因素所确定的链结构层次包括相对分子质量以及构造、构型等同分异构体形式;物理因素所确定的结构层次为高分子局部质点集合在空间的堆砌和排列;链段是容易被忽视、但又是最为重要的运动(变化)单元。     

掺杂聚合物对溶致液晶结构的影响

利用聚合物大分子作构建组分,将其掺杂到不同类型表面活性剂构成的溶致液晶中,考察对液晶相结构的影响．利用小角X射线散射及偏光显微镜对聚合物掺杂前后液晶的结构进行表征,并讨论了聚合物与液晶模板间的相互作用．对阴离子型表面活性剂琥珀酸二异辛酯磺酸钠(AOT)／水液晶体系,聚合物的嵌入使层间距d增大;而对非离子表面活性剂十二烷基聚氧乙烯醚(C12EO4)／水体系,除小分子量的聚乙二醇PEG400外,其它聚合物嵌入使d减小,表明聚合物分子类型、大小及浓度对溶致液晶的结构参数甚至组装方式有不同的影响机制．     

共轭聚合物发光和光伏材料研究进展

聚合物光电功能材料与器件因其广阔的应用前景,1990年以年来吸引了世界各国学术界的广泛关注和兴趣.聚合物光电子器件主要包括聚合物电致发光二极管、聚合物场效应晶体管和聚合物太阳能电池等,其使用的关键材料是共轭聚合物光电子材料,包括共轭聚合物发光材料、场效应晶体管材料和光伏材料等.本文主要对共轭聚合物电致发光材料和光伏材料的研究进展进行综述,介绍了这些聚合物材料的种类、结构和性质以及在聚合物电致发光器件和聚合物太阳能电池中的应用.并讨论了当前共轭聚合物光电子材料中的关键科学问题和今后的发展方向.     

Synthesis of polyolefin composition in the presence of supported catalysts

Polyolefins are basic materials in the plastics. Their application is limited by their low thermostability, adhesion, hardness and other physico-mechanical properties. The following treatments are known to improve and modify polyolefin properties: the incorporation of inorganic or organic fillers with a greater hardness and rigidity into the polyolefin matrix, the grafting of functional groups to polyolefins, and crosslinking with the formation of a network structure in the polyolefin matrix. In the case of polymers and inorganic materials, the activation of their surface by the functionalizing and fixing of transition metals allows one to perform polymerization of monomers on a surface to obtain a polymer–polymer composites and a highly filled polymer–inorganic composites.