聚乙烯基吡啶共聚物与取代苯基偶氮苯酚复合物的制备及其液晶性质

通过分子间弱相互作用力组装形成的液晶高分子与一般侧链液晶高分子相比，其介晶基元与聚合物主链搭配选择范围宽，且易于组装制备．因此，将氢键［１，２］，离子键［３，４］等引入液晶高分子制备领域，越来越引起人们的兴趣．目前以吡啶 羧基氢键组装成的侧链液晶高分...     

一种通过分子间氢键自组装的侧链液晶聚合物

一种通过分子间氢键自组装的侧链液晶聚合物邢佩祥，赵英英，汤心颐，姜炳政（吉林大学化学系，长春，１３００２３）（中国科学院长春应用化学研究所高分子物理开放实验室）关键词氢键，侧链液晶聚合物，近晶相，自组装自Ｒｉｎｇｓｄｏｒｆ［１］等提出在介晶基团与主链...     

二元组装体集群时的高选择性杂化重组行为

多样性自组装体在混合时,通常表现出互不干扰的自分类性,能高度选择性地自分类堆积.但结构极为相似的组装子在相互混合时,会发生交互作用并表现出重组现象.文中合成和观测了具有芳香环边墙和不同酰胺侧链的C型甘脲分子夹为组装单元的混合组装行为.研究发现,此类分子在各自以单一态物质溶解于CDCl3时,能通过π-π相互作用和氢键形成二聚自组装体;若将两种具有不同酰胺侧链的C型甘脲分子夹两两混合,从理论上推测应有三种二聚自组装堆积态存在：A·A、B·B、A·B.但经1HNMR分析发现了一个有趣的现象,即当酰胺侧链上的取代基R′分别为具有C-H结构（如1和2）与PhF5基（5）的组装体两两混合时,二聚组装主要呈现出高度选择性杂化重组的A·B结构态.这种取代基控制的高选择性重组行为可能是基于π-π相互作用、N—H…O氢键,以及C—H…π等三重作用力的协同结果.     

基于“多链超分子柱”的侧链液晶高分子柱状相

一些具有伸展构象的侧链液晶高分子,如甲壳型液晶高分子或树枝化高分子,可以经由分子链的平行排列而呈现柱状液晶相.一般认为,该类柱状相的基本结构单元是单根高分子链所形成的超分子柱.而以几根链组装形成的超分子柱,即"多链超分子柱",也可作为侧链液晶高分子柱状相的基本结构单元,但多年以来这一现象并未引起人们的重视.近期,我们以hemiphasmid型侧链液晶高分子为研究对象,阐明了"多链超分子柱"是侧链液晶高分子柱状相微相分离的一种重要形式.本文从hemiphasmid型侧链液晶高分子的柱状相结构分析、化学结构对"多链超分子柱"的影响、"多链超分子柱"模型的理论分析与预测、"多链超分子柱"的"柱内缠结"以及hemiphasmid型侧链液晶聚降冰片烯的功能性等若干方面,对基于"多链超分子柱"的侧链液晶高分子柱状相进行了介绍.我们认为,深入研究"多链超分子柱"性质,将拓展侧链液晶高分子的应用领域,加深对高分子物理基本问题的认识.     

甲壳型液晶高分子的构筑、自组装及其功能化

甲壳型液晶高分子的发展很大程度上依赖于聚合物自组装的发展,而各种可设计、可预测、可调控的自组装策略的涌现,将甲壳型液晶高分子研究推向前所未有的高度,同时也极大地丰富了高分子化学与物理的内容,提升了研究水准.研究表明,侧链"甲壳效应"在调控甲壳型液晶高分子有序结构等方面有着重要作用.本综述从甲壳型液晶高分子设计合成、液晶相态调控、嵌段共聚物自组装和功能化应用等方面,总结和评述了近年来该领域国内的最新研究进展.最后,本综述总结了甲壳型液晶高分子在发展中所面临的主要问题,并对其发展趋势进行了展望.     

自增强高性能聚合物的成型工艺同力学性能间相关性研究——1.超高分子量聚乙烯的应力诱导结晶理论和其自增强作用

本文发展了一种高分子量聚合物熔融体的应力诱导结晶结构形态模型,它是由微晶聚集体(以下简称微区)-高分子链组网和缠结网的网络结构组成。基于上述模型,把二种网中的单个链组作为独立的统计单元和形变单元,计算了二种网中单个链组的末端距分布函数,进一步计算了二种网和总网的形变自由能。在此基础上,讨论了诱导结晶结晶机理和自增强聚合物网络自由能的依赖性,并着重地研究了超拉伸高聚物的起始熔点拉伸比间的关系。用超高分子量聚乙烯膜和超取向高密度聚乙烯纤维的起始熔点和拉伸比的实验数据进行处理,得到理论予期的近似直线关系,初步验证了聚合物网应力诱导结晶理论。     

聚类肽高分子材料及其结构与性能的研究

聚类肽又称为氮取代聚甘氨酸(N-聚甘氨酸),是一类具有优良生物相容性以及生物活性的可降解高分子材料.由于酰胺键的活泼氢被取代,聚类肽主链结构中消除了聚肽固有的多重氢键相互作用,其主链柔性较好,聚合物性质主要由侧链基团的种类及其物理化学性质决定.基于这种链结构特征,可以通过设计不同的侧基结构,有效地调节聚类肽高分子的热力学性能、降解性能和自组装行为等物理化学性质.合成聚类肽的方法主要有2种——开环聚合和固相合成.本文主要介绍了聚类肽高分子的本体与溶液自组装行为,系统阐明了如何通过调控聚类肽高分子的侧链结构,研究链结构与自组装行为之间的相互关系,进一步构筑具有独特相分离行为以及自组装结构的新型生物高分子,同时探讨了这些材料在生物医用和能源等领域的潜在应用.     

柔性高分子/液晶体系的相平衡理论

在Flory-HugginS柔性高分子溶液理论和Lebwohl-Lasher液晶模型的基础上;导出了柔性高分子/液晶复合体系的混合自由能和化学位,并计算了相应的相图。计算结果表明,体系可出现各向同性相(Ⅰ)和各向同性相(Ⅰ),以及各向同性相(Ⅰ)和向列相(N)间的相平衡。并且发现,高分子链段与液晶分子间的各向同性相互作用对I/N的相平衡有重要影响。与实验结果的比较表明,本理论能完整、正确地描述高分子/液晶体系的相平衡。     

侧链聚硅氧烷液晶高分子的合成与表征及应用研究

液晶高分子既具有独特的液晶性 ,又具有高分子的良好材料性能 ,引起了人们的广泛注意[1～ 9] .侧链液晶高分子大多可以作为功能材料 ,对它们的研究有很大的理论与现实意义 .以往报道的此类化合物的介晶基元大多是通过烷氧基与间隔基相连[10 ] .我们以催化活性很高的铂络和物为催化剂 ,通过硅氢加成反应制备了间隔基与介晶基元通过酰氧基相连的两种侧链聚硅氧烷液晶高分子 ,并对它们的性质进行了初步表征 .发现它们具有很好的液晶性 .已有研究表明侧链聚硅氧烷液晶在气相色谱分离结构近似的物质方面 ,具有易涂渍、选择性及热稳定性优于低分子…     

刚棒中心含侧基的刚棒-线团分子的合成及聚集体结构分析

合成了一系列三嵌段刚棒-线团分子,这些分子由含有苯、联苯和具有侧基的苯单元与聚合度为7,12及17的不同长度烷氧基链组成.通过氢核磁共振仪(1H NMR)和质谱(MALDI-TOF MS)对其结构进行了表征,利用差示扫描量热法(DSC)、偏光显微镜(POM)和小角X射线散射实验(SAXS)对这些液晶化合物的自组装行为进行了研究.实验结果表明,侧基含酯基的分子1a~1c自组装成层状、倾斜柱状和六方穿孔层状结构;而侧基含羧基的分子2a~2c则自组装成倾斜柱状、体心四方聚集体.可见,随着烷氧基链长度的改变,刚棒中心的羧基和酯基能诱导分子的自组装行为发生变化.     

Complexation of calix[4]arenehydroxymethylphosphonic acids with amino acids. Binding constants determination of the complexes by HPLC method

Host–Guest complexation process of calixarenehydroxymethylphosphonic acids with 10 amino acids in solution H₂O/MeCN (99:1) had been studied. Binding constants of the inclusion complexes from the dependence between capacity factors of the Guest and the calixarene-Host concentration in the mobile phase had been calculated. It was shown the binding constants depend on the nature of the amino acid residue, conformation of the calixarene skeleton, quantity of phosphoryl groups at the upper rim. In accordance with molecular calculation the complexation is determined by the electrostatic interactions between the positively charged nitrogen atom of amino acid and the negatively charged oxygen atom of phosphonic group of calixarene molecule, hydrogen bonds, π–π, CH–π and solvatophobic, interactions.     

Superhydrogels of Nanotubes Capable of Capturing Heavy‐Metal Ions

Self‐assembly regulated by hydrogen bonds was successfully achieved in the system of lithocholic acid (LCA) mixed with three organic amines, ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA), in aqueous solutions. The mixtures of DEA/LCA exhibit supergelation capability and the hydrogels consist of plenty of network nanotubes with uniform diameters of about 60 nm determined by cryogenic TEM. Interestingly, the sample with the same concentration in a system of EA and LCA is a birefringent solution, in which spherical vesicles and can be transformed into nanotubes as the amount of LCA increases. The formation of hydrogels could be driven by the delicate balance of diverse noncovalent interactions, including electrostatic interactions, hydrophobic interactions, steric effects, van der Waals forces, and mainly hydrogen bonds. The mechanism of self‐assembly from spherical bilayer vesicles into nanotubes was proposed. The dried hydrogels with nanotubes were explored to exhibit the excellent capability for capturing heavy‐metal ions, for example, Cu²⁺, Co²⁺, Ni²⁺, Pb²⁺, and Hg²⁺. The superhydrogels of nanotubes from the self‐assembly of low‐molecular‐weight gelators mainly regulated by hydrogen bonds used for the removal of heavy‐metal ions is simple, green, and high efficiency, and provide a strategic approach to removing heavy‐metal ions from industrial sewage.     

Construction of halogen and hydrogen bond‐based multicomponent nanostructures at liquid‐solid interface

The cooperative effect of hydrogen and halogen bonds on the 2‐dimensional molecular arrangement of highly oriented pyrolytic graphite has been studied by scanning tunneling microscopy. The scanning tunneling microscopy observations demonstrate that the self‐assembled hydrogen‐bonded molecular chicken‐wire networks of trimesic acid have been significantly transformed after annealing and the introduction of tribromobenzene guest molecules. Bromine atoms and carboxyl groups were found to form 2 different multicomponent structures via hydrogen and halogen bonds. Owing to the effect of halogen and hydrogen bonds, tribromobenzene with trimesic acid formed the 3‐fold symmetry networks.     

Phase equilibrium and diffusion in binary systems based on nonyl acrylate, acrylic acid, and their homo- and copolymers

The phase equilibrium and diffusion in systems based on nonyl acrylate, acrylic acid, and their homopolymers and copolymers of different compositions have been studied in the range of 20–100°C by the microinterference technique. For the systems with the limited solubility of components, the phase diagrams have been constructed. It has been established that, with a rise in the content of carboxyl groups in the copolymers, the diffusion coefficients and the thermodynamic compatibility of the monomers decrease. It is suggested that the nonlinear pattern of a variation in the diffusion coefficient with the content of acrylic acid in the copolymers is predominantly associated with a change in the type of hydrogen bonds and the formation of carboxyl dimers upon the transition to poly(acrylic acid). The concentration of carboxyl groups may serve as a parameter indicating variations in thermodynamic compatibility and diffusion constants of the monomers with the intensity and type of hydrogen bonds in the polymers under study. The presence of hydrogen bonds and their type are estimated on the basis of the IR spectra of the homo- and copolymers of interest.     

Cooperative Effect of a Classical and a Weak Hydrogen Bond for the Metal‐Induced Construction of a Self‐Assembled β‐Turn Mimic

A novel metal‐induced template for the self‐assembly of two independent phosphane ligands by means of unprecedented multiple noncovalent interactions (classical hydrogen bond, weak hydrogen bond, metal coordination, π‐stacking interaction) was developed and investigated. Our results address the importance and capability of weak hydrogen bonds (WHBs) as important attractive interactions in self‐assembling processes based on molecular recognition. Together with a classical hydrogen bond, WHBs may serve as promoters for the specific self‐assembly of complementary monomeric phosphane ligands into supramolecular hybrid structures. The formation of an intermolecular C? H???N hydrogen bond and its persistence in the solid state and in solution was studied by X‐ray crystal analysis, mass spectrometry and NMR spectroscopy analysis. Further evidence was demonstrated by DFT calculations, which gave specific geometric parameters for the proposed conformations and allowed us to estimate the energy involved in the hydrogen bonds that are responsible for the molecular recognition process. The presented template can be regarded as a new type of self‐assembled β‐turn mimic or supramolecular pseudo amino acid for the nucleation of β‐sheet structures when attached to oligopeptides.     

Dielectric investigation of a binary system of self-organized diols

Dielectric measurements on a binary system of two liquid crystalline diols were carried out. These show a SmA and a cubic phase. In the middle concentration range of the system, a columnar phase is induced. The self assembly of the molecules giving different liquid crystalline phases is clearly seen in the dielectric spectrum, and therefore details of this process may be discussed. All the samples show a high frequency dielectric absorption which is related to the dynamics of the network of hydrogen bonds. In the columnar phase an additional low frequency mechanism is seen which may be caused by the internal dynamics in the columns.     

CHARACTERIZATION OF POLY(VINYL ALCOHOL)-KONJAC GLUCOMANNAN BLEND FILMS

This article deals with the characterization of blend films obtained by mixing poly(vinyl alcohol) (PVA) and konjac glucomannan (KGM) in aqueous solution. The DTA curves of PVA/KGM blend films showed overlapping of the main thermal transitions characteristic of the individual polymers. The exothermic peak at 312°C, which resulted from the thermal degradation of the KGM, shifted slightly to a higher temperature at low PVA content (≤20 wt%). The weight-retention properties of the blend films indicated that thermal stability of the blend films were better than pure KGM film at PVA content below 20 wt%. The crystallinities, tensile strength, and elongation at break of the films increased with the PVA content, and reached the maximum values at 20 wt% PVA, then decreased. Changes in the carbonyl stretching band of KGM and hydroxyl stretching regions of KGM and PVA were detected by FTIR analysis. Those are attributable to the existence of a certain degree of inteaction between KGM and PVA, and resulted from intermolecular hydrogen bonds. Phase separation phenomena were observed by examining the surface of the blend films by SEM.     

Hydrogen bonds in heterogeneous blends based on semicrystalline polyurethane and styrene-acrylic acid block copolymer

New film-forming polymer composites based on the semicrystalline polyurethane and the styreneacrylic acid block copolymer have been synthesized. The effect of hydrogen bonds on the phase structure and properties of the composites has been studied by dynamic MTA, DSC, thermogravimetry, and IR spectroscopy. Formation of the network of intermolecular hydrogen bonds between urethane groups of polyurethane and carboxyl groups of block copolymer components leads to a decrease in the microphase separation of the composites under study and improves their thermooxidative stability.     

Influence of Ester versus Amide Linkers on the Supramolecular Polymerization Mechanisms of Planar BODIPY Dyes

We report the H‐type supramolecular polymerization of two new hydrophobic BODIPY derivatives equipped with ester and amide linkages. Whereas the ester‐containing BODIPY derivative undergoes an isodesmic supramolecular polymerization in which the monomers are parallel‐oriented, the replacement of the ester by amide groups leads to a highly cooperative self‐assembly process into H‐type aggregates with a rotational displacement of the dye molecules within the stack. The dye organization imposed by simultaneous π–π and hydrogen bonding interactions is the driving force for the cooperative supramolecular polymerization, whereas the absence of additional hydrogen bonds for the ester‐containing moiety does not suffice to induce cooperative phenomena.     

原位配体功能化策略制备共价金属有机骨架促进其析氢反应

新型多孔材料在诸多领域具有广阔的应用前景,其发展引起了研究者较大关注.在过去的十年中,大量的先进多孔材料被设计并应用于不同领域.其中,共价有机骨架(COFs)和金属有机骨架(MOFs)材料由于具有结构多样、孔隙可调以及功能多样等独特性质,得到了广泛研究.为了有效地结合各个组分的优点以获得最优性能,科研工作者投入了大量的...