螺旋型高分子链晶体结构所属空间群的演变规律性

本文利用有色对称的理论讨论了螺旋型高分子链晶体结构所属空间群的演变规律性。得出：（１）有序链结构的空间群是无序链结构空间群的有色空间群；（２）对称性较低的螺旋链所属空间群是高对称螺旋链所属空间群的有色空间群；（３）从而得出空间群演变的方向、途径和结果，总结出其演变的规律性。     

二维正方形格点上自踪迹规避链的临界指数

用实空间中的重整化群理论 ,对二维正方形格点上的高分子模型自踪迹规避链进行了求解 .求得自踪迹规避链的相关长度指数νSAT为 0 759,格点的等效配位数 μSAT为 2 96 8     

聚合物片晶中链折叠模型的对称性讨论

本文从对称的观点讨论了在聚合物片晶中链折叠的问题.提出只有当分子链在折向相反方向后对称性不改变时,近邻规整折叠才是可能的.它是近邻折叠的必要条件.根据折叠时“对称性不变”这一论点,可以预言分子链近邻规整折叠的可能性及可能的折叠方向.     

对称性轨道的构造

提出1种以配体轨道的旋转性质为基础,并利用群生成元表示矩阵来构造对称性轨道的新方法。讨论了对称性系数之间的相互关系,同时给出群重迭积分的计算过程。     

受限高分子链的静态与动态性质

受限条件下高分子链的静态与动态性质是高分子物理学研究的重要组成部分,也是生物物理学关注的焦点问题之一。相对于自由高分子链,受限高分子链往往随受限程度和受限区域的不同而表现出一系列独特的规律性。本文首先回顾了自由空间中高分子链的基本性质,然后重点介绍了在不同受限程度下高分子链的静态性质和动力学行为,对比了不同受限区域下这些性质的差异性,并且系统总结了流场诱导下高分子链过孔的经典理论及其详细推导过程。最后,展望了受限高分子链今后的发展方向。     

全同立构聚丙烯晶体结构的对称性研究

本文利用对称理论,研究了全同立构聚丙烯的α(型)晶及β(型)晶的可能的晶体结构.1.推导了与C2/c空间群有关的有色空间群,研究了聚丙烯分子链在它们中的排布,得出其中5种是聚丙烯α(型)晶晶体结构可能存在的空间群;2.从晶畴理论出发,得出具有Cc空间群与P2_(1/c)空间群的两种晶畴共存于一个体系中,3.聚丙烯β(型)晶的晶体结构的可能排列方式是聚丙烯分子链按R型晶胞的半无规排列。     

高分子物理的近代理论方法

三.重整化群理论 K.Wilson在七十年代提出了重整化群理论,这个理论是把量子场论中的方法应用到临界现象上,它的特点是可以计算出临界指数的数值。真正要了解重正化群的计算必须要相当多的数学准备。这里我们只能结合高分子构象问题介绍它的基本思想。 一条处于良溶剂中的高分子链,它共有N个链段,空间维数为d,按照Flory和Edward理     

Noether原理在化学中的应用(Ⅱ) 反应反演与空间称(英文)

在前文中,按Noether原理讨论了与点群相关的不变量及有关的守恒规则.本文分析了反应反演变换及其与点称联合的对称性,建立了与此种对称性相关的守恒规则.利用这些结果示出σ迁移反应与歧化反应的选择规则.此外,与空间群相关的守恒规则与不变量在本文中亦作讨论.     

弱电场驱动下高分子链在周期管道内输运的模拟研究

采用Langevin动力学方法模拟研究了弱电场驱动下高分子链在无限长周期管道中的输运过程. 管道由长度相等的α和β两部分周期排列而成, 其中高分子链与α管道间存在相互吸引作用, 而与β管道间存在纯排斥作用. 模拟结果表明, 高分子链在输运过程中存在明显的受限阶段, 其逃离受限的方式与管道宽度有关且满足不同的规律. 对于窄管道, 高分子链在输运过程中呈直线伸展构型且运动具有“蛇爬行”特征. 高分子链逃离受限过程伴随着整条链的运动, 从而导致迁移率随高分子链长呈周期变化, 而且在迁移率极值位置, 高分子链投影长度与管道半周期之间存在简单的整数倍关系. 对于宽管道, 高分子链在输运过程中出现弯折构型且运动具有“蠕虫运动”特征. 当链长比较长时, 高分子链可通过链前端部分的伸长逃离受限, 从而导致迁移率与高分子链长度无关. 模拟结果可能有助于利用周期管道对不同长度的高分子链进行分离及可控输运.     

单链高分子通过薄膜上纳米孔隙的输运过程: 链间相互作用的影响

从理论上研究了高分子链通过位于薄膜上的一个纳米孔隙的输运问题. 考虑在膜的一侧引入与传输高分子链有特殊相互作用的高分子链段, 研究链间相互作用致使高分子链构型的改变对其平均首次通过时间的影响, 进而在不同条件下进行了相应的数值模拟, 并讨论了其它一些相关问题.     

Reactive Groups,Spacer Groups and Functional Groups in Macromolecular Design

Several aspects of modern design of macromolecular architecture are discussed: the influence and importance of functional groups which often dominate the characteristics of the macromolecular structure; the importance of the spacer groups that provide flexibility and allow the functional group to act independently from the main chain when the functional group is attached to the main chain.

Examples are given for the synthesis of reactive, telechelic polymers, for polymerizability of monomers whose polymerizable group is separated from the functional group by a flexible methylene spacer, and the reactivity of functional groups separated from the main chain by a spacer group.     

The Orbifold Notation for Two-Dimensional Groups

This paper gives a detailed introduction to the orbifold notation for two-dimensional (2-D) symmetry groups. It discusses the correspondence between properties of orbifolds and symmetries in the original surface. The problem of determining a group in situ is addressed. Elementary proofs of the classification of the Euclidean and spherical 2-D symmetry groups are presented.     

Synthesis of styryl-capped polypropylene via metallocene-mediated coordination polymerization: Apply to polypropylene macromolecular engineering

In this paper, we review our recent progress in the synthesis and application of styryl-capped polypropylene (PP-t-St), an excellent reactive polyolefin that is both convenient and efficient in synthesis and facile and versatile in application for preparing advanced polypropylene materials via macromolecular engineering. The synthesis of PP-t-St is made possible by a unique chain transfer reaction coordinated by a bis-styrenic molecule, such as 1,4-divinylbenzene (DVB) and 1,2-bis(4-vinylphenyl)ethane (BVPE), and hydrogen in typical C ₂-symmetric metallocene (e.g. rac-Me₂Si(2-Me-4-Ph-Ind)₂ZrCl₂, in association with methylaluminocene, MAO) catalyzed propylene polymerization. The regio-selective 2,1-insertion of the styrenic double bond in DVB or BVPE into the overwhelmingly 1,2-fashioned Zr-PP propagating chain enables substantial dormancy of the catalyst active site, which triggers selective hydrogen chain transfer that, with the formed Zr-H species ultimately saturated by the insertion of propylene monomer, results in an exclusive capping of the afforded PP chains by styryl group at the termination end. With a highly reactive styryl group at chain end, PP-t-St has been used as a facile building block in PP macromolecular engineering together with the employment of state-of-the-art synthetic polymer chemistry to fabricate broad types of new polypropylene architectures.     

Aromatic Heterocycles Used as Terminal Groups of Calamitic Liquid Crystals

Three series of compounds 1 ‐ 21 were prepared by using 2‐, 3‐, and 4‐pyridinemethanol as terminal group of calamitic liquid crystals. These compounds have some similarities in their phase behavior. They all exhibit SmA phase. A tilt smectic phase, SmC, will be formed when their flexible alkoxy chain is longer than hexoxy group. The profound difference between them is that the compounds 15 ‐ 17 possess a short temperature range of N phase. The compounds 3 and 6 have the widest SmA phase, up to 94 °C, and SmC phase, up to 46 °C, respectively.     

Representations of Shavitt Graphs Within the Graphical Unitary Group Approach

The Shavitt graph is a visual representation of a distinct row table (DRT) within the graphical unitary group approach. The DRT is a compact representation of the entire configuration state function expansion space within a molecular electronic structure calculation. Each node of the graph is associated with an integer triple (a _k,b _k,c _k). These integers may be mapped to other quantum numbers, including the number of orbitals, number of electrons, and spin quantum number, and used to display Shavitt graphs in various ways that emphasize different aspects of the expansion space or that reveal different aspects of computed wave functions. The features of several graph density plots are discussed, including electron–hole symmetries and the bonding–antibonding wave function character. © 2019 Wiley Periodicals, Inc.     

Proteomics‐based Characterization of Protein Complexes from Human Pancreatic Cancer Cell Line

To develop an economical and feasible approach to probe protein complexes, differential centrifugation and three‐dimensional polyacrylamide gel electrophoresis (PAGE) were performed to separate protein complexes from the cell lysate of human pancreatic cancer cell line, SW1990, followed by mass spectrometric identification. Four macromolecular protein complexes were separated and identified unambiguously.     

Line and boundary tensions on approach to the wetting transition

A mean-field density-functional model often used in the past in the study of line and boundary tensions at wetting and prewetting transitions is reanalyzed by extensive numerical calculations, approaching the wetting transition much more closely than had previously been possible. The results are what are now believed to be definitive for the model. They include strong numerical evidence for the presence of the logarithmic factors predicted by theory both in the mode of approach of the prewetting line to the triple-point line at the point of the first-order wetting transition and in the line tension itself on approach to that point. It is also demonstrated with convincing numerical precision that the boundary tension on the prewetting line and the line tension on the triple-point line have a common limiting value at the wetting transition, again as predicted by theory. As a by product of the calculations, in the model's symmetric three-phase state, far from wetting, it is found that certain properties of the model's line tension and densities are almost surely given by simple numbers arising from the symmetries, but proving that these are exact for the model remains a challenge to analytical theory.     

On Deciding between Space Groups Pnam and Pna21 for the Crystal Structure of Zr3N4

The crystal structure of Zr₃N₄ is shown to crystallize in the centrosymmetric space group Pnam rather than in the noncentrosymmetric space group Pna2₁.     

含羧基的含氟嵌段共聚物的合成及表面性能研究

利用原子转移自由基聚合反应以及随后的大分子链中叔丁酯基团的水解反应,合成了一系列具有不同含氟量和羧基含量的二嵌段共聚物,并分别通过GPC, ¹H NMR和FT-IR对共聚物的组成和结构进行了表征.进一步考察了这些含羧基或羧酸钠基团的含氟嵌段共聚物在吡咯烷酮或水中的溶解性能、临界胶束浓度、表面活性、达到饱和吸附时每个分子在表面所占据的面积,以及成膜后的临界表面张力等性能.实验结果表明,此含氟嵌段共聚物能显著降低吡咯烷酮和水的表面张力,成膜后表现出与聚四氟乙烯极为接近的低表面能特性.