基于氢键作用的超分子聚合物的研究进展

氢键的温度敏感性和可逆性对聚合物热力学性质、微观自组装、结晶及液晶行为有重要影响,因而在超分子聚合物的设计与结构控制方面受到广泛关注。详细介绍了氢键型超分子聚合物的研究现状及其进展。     

Hydrogen Bonding Modules for Use in Supramolecular Polymers

Supramolecular polymer chemistry has emerged as a major research focus within polymer science, because of the potential to improve material properties, through the combination of noncovalent interactions and synthetic polymers. As a supramolecular handle, the most useful noncovalent interaction is hydrogen bonding, which has been used extensively, because of advantages such as synthetic accessibility, directionality, fidelity, and, most importantly, responsiveness to external stimuli. This review introduces recent advances in the development of hydrogen bonding modules that can be useful for creating a variety of supramolecular polymers. Furthermore, we present selected examples of hydrogen bonded supramolecular polymers from the literature, by dividing them into three categories: supramolecular polymers assembled from small molecules, and main-chain and side-chain supramolecular polymers.     

超分子环糊精的研究新进展

随着环糊精衍生物不断被合成、环糊精的性质不断被发现,超分子环糊精的应用也越来越广泛。综述了超分子环糊精在分子识别、分子自组装和模拟生物酶等方面的研究进展,展望了超分子环糊精的发展趋势。     

超分子自组装及其在高分子合成领域中的应用

超分子自组装是近年来倍受重视的国际前沿课题,它将会极大促进信息、能源、生命、环境和材料科学等学科领域的发展,介绍了基于氢键、π键、配位键、双亲分子4种自组装体系,重点综述了这4种自组装体系在高分子合成领域中的最新进展,最后对超分子自组装的发展趋势做了展望。     

Influence of Topology of Highly Porous Methacrylate Polymers on their Mechanical Properties

Porous polymer monoliths are prepared using glycidyl methacrylate and methyl methacrylate as monomers, in both cases crosslinked with ethylene glycol dimethacrylate. Up to 75% porous samples are produced using either emulsion templating or bulk polymerization with porogens. In the case of emulsion templating, a cellular topology with cavities between 3.1 and 5.5 µm is observed for both monomers, while a cauliflower‐like topology is formed in the case of bulk polymerization. The influence of topology features of monoliths on the mechanical properties is studied and for both polymers a dramatic influence, on both compressive moduli and compressive strength, is found. The mechanical parameters, namely elastic modulus and compressive strength are significantly higher for emulsion templated samples.     

Actomyosin Interaction: Mechanical and Energetic Properties in Different Nucleotide Binding States

The mechanics of the actomyosin interaction is central in muscle contraction and intracellular trafficking. A better understanding of the events occurring in the actomyosin complex requires the examination of all nucleotide-dependent states and of the energetic features associated with the dynamics of the cross-bridge cycle. The aim of the present study is to estimate the interaction strength between myosin in nucleotide-free, ATP, ADP·Pi and ADP states and actin monomer. The molecular models of the complexes were constructed based on cryo-electron microscopy maps and the interaction properties were estimated by means of a molecular dynamics approach, which simulate the unbinding of the complex applying a virtual spring to the core of myosin protein. Our results suggest that during an ATP hydrolysis cycle the affinity of myosin for actin is modulated by the presence and nature of the nucleotide in the active site of the myosin motor domain. When performing unbinding simulations with a pulling rate of 0.001 nm/ps, the maximum pulling force applied to the myosin during the experiment is about 1nN. Under these conditions the interaction force between myosin and actin monomer decreases from 0.83 nN in the nucleotide-free state to 0.27 nN in the ATP state, and increases to 0.60 nN after ATP hydrolysis and Pi release from the complex (ADP state).     

Mechanical Properties of Polymers Filled with Iron Powder

Mechanical properties of metal-polymer matrix composites were investigated experimentally. High density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS) were used as the polymer matrix and Fe powder in 5, 10, and 15 vol% was used as the metal. The modulus of elasticity, yield and tensile strength, % elongation, Izod notched impact strength, Shore D hardness, and fracture surfaces of the composites were determined. It was found that vol% Fe reduced the Izod impact strength of HDPE much more than that of PP and PS, while Fe powder increased the hardness of HDPE more than that of PP and PS. Among the composites, PS-Fe composites had higher yield, tensile strength and modulus of elasticity than HDPE-Fe and PP-Fe composites. However, % elongation of PS-Fe composites was lower than that of the other composites. In addition, HDPE- and PP-based composites exhibited ductile type fracture, while PS-Fe composites exhibited brittle type fracture.     

高分子共混物的相结构对力学性能的影响

本文以聚丙烯 尼龙1010(PP PA1010)共混体系为模型研究了高分子共混物的微观相结构对宏观力学性能的影响,并通过微观力学模型来预测共混物的拉伸强度。通过光散射试验和扫描电镜结果讨论了两相平均弦长比(L1 L2)以及分散相的质心相关距(D)与拉伸性能的关系。结果表明,当分散相一定时,拉伸强度随两相相对尺寸的增大和分散相颗粒相关性的减弱而减小。理论计算的分散相最小体积分数与相形貌观察的结果非常接近,添加增容剂的体系,由于改善了界面粘合,使理论预测值与试验结果很好的吻合。     

Effects of the Molecular Design on the Supramolecular Organization of Luminescent Pt(II) Complexes

Self‐assembly is an extremely important processes that allows the constructions of large supramolecular architectures through encoded information present in the components. A subtle change in the chemical structure of the single unit can dramatically change the kinetics and thermodynamic pathway. We demonstrate that a minor change, introduced by designing the structure of a family of Pt(II) complexes can influence the color of the emission of the assemblies and their kinetic behaviour. The assembly processes, visualized by confocal microscopy, and detailed through photophysical measurements, reveal that the establishment of intermolecular interactions, as well as electronic factors lead to completely different assemblies in solution of the platinum compounds. A correlation between the observed behaviour and the chemical structure of the compounds is discussed and the results indicate a strong kinetic control of the supramolecular processes.     

Mechanical Properties of Single-Layer Diamond Reinforced Poly(vinyl alcohol) Nanocomposites through Atomistic Simulation

Low-dimensional carbon nanostructures are ideal nanofillers to reinforce the mechanical performance of polymer nanocomposites due to their excellent mechanical properties. Through molecular dynamics simulations, the mechanical performance of poly(vinyl alchohol) (PVA) nanocomposites reinforced with a single-layer diamond – diamane is investigated. It is found the PVA/diamane exhibits similar interfacial strengths and pull-out characteristics with the PVA/bilayer-graphene counterpart. Specifically, when the nanofiller is fully embedded in the nanocomposite, it is unable to deform simultaneously with the PVA matrix due to the weak interfacial load transfer efficiency, thus the enhancement effect is not significant. In comparison, diamane can effectively promote the tensile properties of the nanocomposite when it has a laminated structure as it deforms simultaneously with the matrix. With this configuration, the interlayer sp³ bonds endows diamane with a much higher resistance under compression and shear tests, thus the nanocomposite can reach very high compressive and shear stress. Overall, enhancement on the mechanical interlocking at the interface as triggered by surface functionalization is only effective for the fully embedded nanofiller. This work provides a fundamental understanding of the mechanical properties of PVA nanocomposites reinforced by diamane, which can shed lights on the design and preparation of next generation high-performance nanocomposites.     

基于超分子化学方法制备自愈合聚合物材料的研究进展

本文综述了超分子化学方法制备自愈合聚合物材料的研究进展,着重介绍了利用氢键、π-π键、离子键等非共价键主-客体相互作用来制备自愈合聚合物材料的研究现状。     

柱芳烃合成及应用研究进展

柱芳烃是一类结构对称、由对苯二酚或对苯二酚醚通过亚甲基对位桥联的新型“柱”状大环低聚超分子主体化合物。本文主要回顾了烷氧基柱芳烃、水溶性柱芳烃、两亲性柱芳烃的合成发展过程,介绍了柱芳烃的结构与构象,柱芳烃及其衍生物的主客体化学,阐述了它们在构筑超分子自组装体系、医药、生物、相转移催化方面的应用研究进展。目前,柱[5,6]芳烃的合成方法已经比较成熟,而高阶柱芳烃的合成仍有待进一步改善,同时,随着研究的不断深入,柱芳烃及其衍生物将有望用于催化、生物模拟、石油化工等更广泛的领域。     

Advances in Organometallic Polymers,Ring-Opening Polymerization and the Self-Assembly of Supramolecular Polymers

A personal account is given of the synthesis and properties of polymers and networks containing late transition metal centers in the backbone, especially by using ring-opening polymerization of macrocycles and/or the techniques of supramolecular chemistry. Using these methods, coupled with dynamic coordination chemistry, polymers can be assembled into unusual sheet or network structures by using ligands with hydrogen bonding substituents, or by secondary bonding between inorganic centers. Complexes containing racemic binaphthyl groups in the ligands may self-assemble selectively to give homonuclear or heteronuclear polymers. Bicyclic metal complexes can undergo single ring-opening to form chains or double ring-opening to form sheets.     

高聚物黏结炸药的力学性能研究进展

从材料的力学行为特性、实验方法、本构模型和强度理论4个方面对高聚物黏结炸药(PBX)的力学性能特征进行了归纳和评述。指出应变率和温度对材料应力状况的影响及动态力学性能分析是目前PBX研究的热点和难点。认为可以借鉴研究混凝土和高聚物的一些方法来建立PBX的本构模型和失效准则。指出选择和改进现有测试技术时,须考虑PBX的含能敏感性、大变形等特性。对PBX力学性能的理论研究、实验技术及数值模拟等方面需要开展的工作提出了一些看法。认为复杂环境下的力学响应和细观建模模拟应是今后研究的重点方向。附参考文献93篇。     

Selective Disruption of Survivin's Protein-Protein Interactions: A Supramolecular Approach Based on Guanidiniocarbonylpyrrole

Targeting specific protein binding sites to interfere with protein-protein interactions (PPIs) is crucial for the rational modulation of biologically relevant processes. Survivin, which is highly overexpressed in most cancer cells and considered to be a key player of carcinogenesis, features two functionally relevant binding sites. Here, we demonstrate selective disruption of the Survivin/Histone H3 or the Survivin/Crm1 interaction using a supramolecular approach. By rational design we identified two structurally related ligands ( L_NES and L_HIS ), capable of selectively inhibiting these PPIs, leading to a reduction in cancer cell proliferation.     

弱分子间力超分子液晶性能的分析

超分子液晶是利用氢键、离子相互作用、电荷转移相互作用、疏水相互作用及范德华力等弱分子间相互作用构筑的多种超分子液晶复合体系。超分子液晶复合体系具有质量或电荷传输性、传递性、信息储存功能、分子传感等动态功能性、环境友好性及低能耗加工性等特点。对超分子液晶的性能影响因素进行了深入分析与研究,并对超分子液晶分类进行了介绍。     

聚合物/CNTs复合材料制备及其力学性能影响因素

综述了近年CNTs增强聚合物复合材料的制备方法,重点分析了制备过程中影响复合材料力学性能的主要因素,总结了聚合物/CNTs复合材料制备过程中存在的技术难题并对其未来的发展应用进行了展望。     

Effect of Reinforcement Orientation on the Mechanical Properties of Microfibrillar PP/PET and PET Single‐Polymer Composites

In situ PET microfibrils are created by drawing melt‐blended PP and PET. The drawn blend is used to prepare polymer/polymer MFCs, and isolated PET microfibrils are used for the manufacturing of MF‐SPCs. Samples are prepared with different fibril orientations to determine the effect of orientation on the mechanical properties of the two types of composites. The resulting composites show improvements in stiffness of 77% for uniaxial MFCs, and 125% for uniaxial MF‐SPCs, with the highest recorded modulus of 8.57 GPa for a uniaxial MF‐SPC sample. SEM observations confirm that the fibrillar structure and excellent alignment is maintained. The changes in the reinforcement effect with orientation are very similar to those predicted by the rule of mixtures for the crossply.

     

三种小檗碱衍生物的结构性质及与DNA作用的理论研究

运用Materials Studio程序的DMol3模块对小檗碱衍生物(即9-氧-二胺乙基小檗碱)分别与乙醛、苯甲醛和l-萘醛发生缩合反应所得产物的几何结构和性质(振动频率、反应活性及热力学性质)进行了理论研究,得到了分子的稳定几何构型、Fukui指数、前线分子轨道和热力学性质.通过计算得到的吉布斯自由能的改变量,预测...     

Effect of Hyaluronic Acid on the Self-Assembly of a Dipeptide-Based Supramolecular Gel

The combination of polymers and low molecular weight (LMW) compounds is a powerful approach to prepare new supramolecular materials. Here we prepare two-component hydrogels made by a well-known and biologically active polymer, hyaluronic acid ( HA ), and a dipeptide-based supramolecular gelator. We undertake a detailed study of materials with different compositions including macroscopic (hydrogel formation, rheology) and micro/nanoscopic characterization (electron microscopy, X-ray powder diffraction). We observe that the two components mutually benefit in the new materials: a minimum amount of HA helps to reduce the polymorphism of the LMW network leading to reproducible hydrogels with improved mechanical properties; the LMW component network holds HA without the need for an irreversible covalent crosslinking. These materials have a great potential for biomedical application as, for instance, extracellular matrix mimetics for cell growth. As a proof of concept, we have observed that this material is effective for cell growth in suspension and avoids cell sedimentation even in the presence of competing cell-adhesive surfaces. This may be of interest to advanced cell delivery techniques.