Synthesis and properties of polymer from bis‐3,4‐ethylenedioxythiophene substituted acenaphthenequinoxaline

A new electrochoromic polymer poly(8,11‐bis(3,4‐ethylenedioxy thiophen‐2‐yl)acenaphtho[1,2‐b]‐quinoxaline) (PBEAQ) was synthesized by electrochemical polymerization of the corresponding monomer (BEAQ) in a 0.1 M tetraethylammonium tetrafluoroborate (TEABF₄) dichloromethane–acetonitrile (2 : 1, v : v) solution. The monomer and polymer were characterized by elemental analysis, ¹H‐NMR, IR, and UV‐vis spectroscopy. The electrochemical and optical properties of polymer were investigated by cyclic voltammetry and UV‐vis spectroscopy. Cyclic voltammetry and spectroelectrochemistry studies demonstrated that the polymer can be reversibly reduced and oxidized (both n‐ and p‐doped) between ?2 V and +1.5 V vs. Ag/Ag⁺. The polymer had a transmissive light blue color in the oxidized state and reddish color in the reduced state. Undoped polymer shows UV‐vis absorption peaks at 615 nm in solution, 650 nm in solid state, and has an optical band gap of 1.5 eV. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

New soluble rigid rod copolymers comprising alternating 2-amino-pyrimidine and phenylene repeat units: Syntheses, characterization, optical and electrochemical properties

A new type - π-conjugated copolymers of 2-amino-pyrimidine was prepared between 2-amino-4,6-diiodidepyrimidine and 1,4-dibromo-2,5-dialkoxybenzene by Sonogashira polycondensation. The structures of the copolymers were elucidated by FT-IR, ¹H NMR and ¹³C NMR, fluorescence spectroscopy, gel permeation chromatography, thermal analysis and element analysis. The derived polymers were soluble in common organic solvents and trifloroacetic acid and exhibited good thermal stability. They emitted green light under UV irradiation in solid state and blue or green light in solution phase, respectively. Electrochemical behavior of these new polymers depicted facile p-doping and good electron-transporting properties. These polymers displayed bathochromic shift when protonated with CH₃SO₃H acid in chloroform solutions or m-cresol solutions and the red-shifted peaks were observed from 490 nm to 652 nm. XRD patterns of copolymers showed that the intensity of peaks was enhanced with increasing alkyloxy chain length.     

氮氧化物光波导传感元件的研究

氮氧化物是造成全球变暖和产生酸雨的主要物质,因此氮氧化物气体的检测在环境监测和化学工业等许多领域中具有重要意义.该文以甲基绿为敏感试剂,将其掺杂于聚乙烯醇溶液后固定在钾离子玻璃光波导上,研制出检测氮氧化物气体的高灵敏度光波导传感元件.该元件具有响应快、成本低、易制作等特点.可检测出浓度为1.91 mg/m3的二氧化氮气体.     

用三维电镜断裂面图像数据测试空穴形状

对金属基复合材料的断裂面,进行三维损伤测试,改进Gurson,Tveergard提出的损伤模型。为建立有限单元模型,进行数值模拟计算,分析在不同三维应力下空穴聚合时空穴几何形状的变化。为准确模拟金属材料及其零部件在多向外载荷下的损伤过程,判断损伤机理提供合理强度评价方法和科学依据.     

漏极散射机制对弹道和非弹道沟道应变硅二极管中电子输运特性的影响

在漏极区域，多重散射对于沟道区域有无散射的应变硅二极管中电子传输性能的影响进行了数值研究。使用应变和散射模型，对于非弹道（有散射）沟道硅二极管的性能与弹道（无散射）沟道的硅二极管的性能进行了比较研究。研究结果表明应变模型中的电子速度和电流的值比无应变模型的相应值更高，弹道沟道模型中的电子速度和电流的值比非弹道沟道模型中的相应值更高。使用应变和散射模型，漏极区域中的每个散射机制对于硅二极管性能的影响进行了分析。对于弹道沟道模型，结果表明谷间光学声子散射会提高器件的性能，而谷内声学声子散射会降低器件的性能。对于应变模型，结果表明较大应变硅能带分裂可以抑制谷间声子散射率。总而言之，为了提高纳米级弹道器件性能，对于漏极区域应变和散射机制模型的研究是很有必要的。     

复杂空间桁架结构在不同约束条件下的有限元模拟

主要介绍了应用MATLAB计算复杂空间桁架结构在不同条件下节点位移、节点外力、单元应变及应力.此外还应用MATLAB建立了GUI界面以获得更好的通用性,并举例进行了说明.     

Computer simulation of the damage evolution of fiber‐reinforced polypropylene‐matrix composites with matrix defects

The damage evolution of fiber‐reinforced polypropylene‐matrix composites with matrix defects was studied via a Monte Carlo technique combined with a finite element method. A finite element model was constructed to predict the effects of various matrix defect shapes on the stress distributions. The results indicated that a small matrix defect had almost no effect on fiber stress distributions other than interfacial shear stress distributions. Then, a finite element model with a statistical distribution of the fiber strength was constructed to investigate the influences of the spatial distribution and the volume fraction of matrix defects on composite failure. The results showed that it was accurate to use the shear‐lag models and Green's function methods to predict the tensile strength of composites even though the axial stresses in the matrix were neglected. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 64–71, 2007     

Synthesis of two novel acenaphthyl-quinoxaline based low-band gap polymers and its electrochromic properties

Dispersion stability and electrokinetic properties of TiO₂ nanoparticles, dispersed in aqueous solution of polyallylamine hydrochloride (PAAm.HCl) and polyvinyl alcohol (PVA) blends was examined. The electrophoresis method was employed to study electrokinetic properties of nanodispersion by varying pH and temperature with an emphasis on dispersion stability. The measurements were performed over a wide range of pH from 2–12 and temperature from 25–65 °C and the isoelectric points (IEPs) of nanodispersions were determined. The concentration of TiO₂ was varied from 2–12 wt%. The dispersions were found to be quite stable (no sedimentation) over a period of two months. The zeta potential of nanodispersions decreases as the pH increases. When temperature increases, a more distinct decrease in the zeta potential was observed. Such behavior may be due to the changes occurring in the linear dimension of adsorbing macromolecules with increasing temperature. As temperatures increases, the adsorption of polymers causes a decrease in the diffuse layer charge, which leads to a decrease in zeta potential. Also, the increase in ionic strength leads to a compression of the diffuse layer and reduction in the zeta potential. The conductivity of nanodispersions increases for all pH and temperatures studied.     

用局部阻尼波形法的自连贯网格生成法

介绍将生成或已有的有限元规则六面体单元改变成形状复杂且光滑的六面体单元的一种新技术——波形法．简单建立了波形法的数学模型并编程进行了网格生成．实验结果表明,只要把复杂外部形状按波的形式传输给指定的规则六面体单元模型,就可以得到具有复杂外部形状的六面体单元网格模型,且网格生成速度快、不出现单元或节点漏洞、欠缺等问题,同时不受单元类型的限制。     

滚动轴承参数化建模及接触强度分析

采用Visual C++与ANSYS有限元软件的参数化建模与分析功能相结合,创建了滚动轴承的参数化建模及有限元接触强度分析平台.该平台通过输入深沟球轴承、圆柱滚子轴承等系列滚动轴承的关键参数,就自动生成滚动轴承整体的有限元网格模型、边界条件及接触对,最后通过直接调用ANSYS相关模块进行有限元接触强度计算.通过对比分析6208深沟球轴承的赫兹接触强度计算结果与该平台的有限元接触强度计算结果,验证了该平台的有效性,为更深入地研究滚动轴承提供了快捷方便的数值分析平台.