关于含杂HMO中参数h,k的研究

本文对含杂HMO的参数h,κ在较大范围内进行了系统的计算,并设法造一函数F(h,κ)将得到的总π电子能与化合物的原子化热数据进行比较。结果表明,即使对于杂原子二元取代苯的三种异构体面言,对于相同的杂原子都不存在普适的h,κ。计算结果也表明,h,κ参数在一定范围内变动时,对HMO结果在定性方面不会带来实质性的影响.     

Effect of surface-grafted molecular brushes on the adhesion performance of bonded polymers and composite interfaces

This paper reviews the theoretical principles of the macromolecular design of polymer interface/interphase systems for obtaining maximum adhesion and fracture performance of composite materials and adhesively bonded assemblies. Subsequently, a relatively simple and industry-feasible technology for surface grafting molecular brushes is discussed in detail and supported by a range of experimental examples. It is shown, in agreement with contemporary theory, that the use of chemically attached graft chemicals of controlled spatial geometry and chemical functionality enables a significant increase in the strength and fracture energy of the interphase, to the point of cohesive fracture of the substrate, or that of an adjacent medium such as adhesive, elastomer or matrix material. This occurs even after prolonged exposure of investigated systems to adverse environments such as hot water.     

Precise Design of Surface Nano-texture and Surface Chemistry of Polymeric Solids

Surface properties of polymeric materials were controlled by fabrication of nano-structure and submicronorder structure of poly(fluoroalkyl acrylate) using the chemical and physical surface modification techniques. The relationship between the ordered structure of fluoroalkyl (R _f) groups and water repellency mechanism was precisely investigated by grazing-incidence X-ray diffraction, water contact angle measurements and X-ray photoelectron spectroscopy. It was revealed that poly{2-(perfluorooctyl)ethyl acrylate} (PFA-C₈) was crystallized and formed ordered structure to result in high water repellency. Surface nano-texturing onto PFA-C₈ film surface was carried out using an anodic aluminum oxide (AAO) membrane as a mold. The nano-texture of AAO mold with a pore diameter of 200 nm was transformed onto the PFA-C₈ film surface to fabricate nano-structure, which revealed high water and oil repellency. On the other hand, various types of monomers were grafted on the solid surface through surface-initiated atom transfer radical polymerization to result in high-density polymer brushes. Hydrophobic PFA-C₈brush surface revealed a low friction coefficient and a good wear resistance. Water lubrication and low friction were observed on the hydrophilic polymer brush. These polymer brushes were successfully introduced on the commercial fluoropolymer, which has inherent radical initiator functional groups. These results indicated that nano-layer immobilization through surface-initiated polymerization and surface texturing are promising methods to control the surface chemistry and surface structure at dimensions in the nano-meter range.     

Preparation and Characterization of Nafion/Sulfonated SiO2 Molecular Sieve Composite Membranes

A Nafion/sulfonated SiO₂ molecular sieve composite membrane was prepared by solution casting with sulfonated SiO₂ molecular sieve as the modifier. The ATR/FT-IR results showed that sulfonated SiO₂ molecular sieve did not change the structure of the membrane. The SEM and XRD results showed that the molecular sieve was distributed uniformly in the membrane. The proton conductivity, methanol permeability, water content, and swelling degree were measured. Compared with Nafion membrane, the composite membrane had higher water content and proton conductivity and lower methanol permeability. The overall performance was the best when the content of sulfonated SiO₂ molecular sieve was 5 wt%. These results indicated that Nafion/sulfonated SiO₂ molecular sieve composite membranes would be excellent candidate membrane materials for direct methanol fuel cell (DMFC) applications.     

螺旋对称(n1)构型高分子的LCAO/TO-LCTO/HO-LCHO/PO处理 I. 21 螺旋对称高分子能带的计算

螺旋高分子不同具有平移对称性, 而且有转动称性. 我们用一种新的线性组合方法LCAO/TO-LCTO/HO-LCHO/PO(T---translation-periodic, H---helix-periodic)推导了螺旋对称高分子的久期方程, 使它的的建立和求解都大大为简化, 并使其阶数从nxP(n为螺旋轴的重数,也表示平移单元中包含的螺旋单元数; P为每个螺旋单元中的原子轨道数)降为P阶. 本文还制定了直接解复广义本征值问题的EHMO 计算方案. 以聚乙烯和聚乙炔为例做了电子能带结构的计算.     

有机锂化合物中化学键的性质——-反式1,2-二锂代乙烷、1,2-二锂代乙烯和1,2-二锂代乙炔分子中化学键的abinitio研究

用从头计算法计算了电荷密度图和各从是分子轨道的键强参数.结果表明,三个标题化合物的稳定构型都存在双桥式四中心键.追其原因是:这种构型有利于Li的2p轨道的吸电子效应,这种效应可使C-Li键增强.此外,也发现这三个化合物中C-C键的强度大于C=C键,而后者又比C=C键为强,本文亦讨论了这种"反常"的原因.     

沸石的碱性催化:乙醇双分子缩合反应

本文首次发现在碱性沸石上乙醇参数发生以正丁醇为主产物的双分子缩合反应。在所研究的催化剂中, 含铷的LiX沸石表现出最高的反应选择性。研究表明, 这一碱化反应的活性与催化剂的酸碱性质密切相关。催化剂的碱性对反应起决定作用,但催化剂的碱性太强则不利于反应。     

若干新型有机光电功能材料的分子设计、合成与性能 研究

介绍本研究组得到国家自然科学基金资助的四个方面工作的进展。研究了金属有机化合物的结构与非线性光学性质的关系,总结了从分子几何构型着手,根据不同用途,对金属有机非线性光学材料进行分子设计的经验规律;提出了利用“组合式共轭桥”进行有机非线性光学发色团分子设计的新思路,所合成的几个有机化合物既有很大的光学非线性,又有紫移的最大吸收峰;通过化学键将有机发色团分子张到各种高分子的侧链上,合成和表征了潜在的电光高分子和光折变高分子材料;采用无机-有机夹层复合的思路对兼有导电性和强磁性的分子材料进行了探索,将一些有机小分子和导电高分子分别插入了层状无机物MPS3的层间,得到了8个新的分子磁体,而另一夹层化合物则表现了较高的电导率。