超高分子量PE凝胶膜的超拉伸性与旁式构象关系研究

通过ＩＲ方法，观测并讨论了在不同条件下制备的超高分子量ＰＥ（ＷＨＭＰＥ）凝胶膜中旁式（Ｇ构象）构象与超拉伸性的关系，提出了Ｇ构象浓度及分布对ＵＨＭＰＥ凝胶膜超拉伸性影响的新概念，同时也讨论了它与链缠结之间的联系，发现：反映Ｇ构象的相对浓度的比值σ＝Ｉ１３０３Ｉ１３５２随制膜浓度的增大而增加，在临界浓度Ｃ０（０．４～０．５ｇ＠１００ｍｌ）附近所形成的膜，具有超高拉伸性（λ＝２００），其Ｇ构象的变化与Ｍａｔｓｕｏ由比浓粘度提出的缠结链改变相对应；热处理温度比热处理时间对σ值的影响更显著，在一定温度下约４分钟后σ值基本不变；在σ值最低的温度范围拉伸，凝胶膜具有良好的超高拉伸性．     

等离子体辅助合成分子筛膜及其催化性能的研究

首次将等离子体技术应用于分子筛膜的制备，研究了以微波等离子体处理基材表面分子筛膜前驱体辅助水热反应合成支撑β型分子筛膜．利用XRD、SEM、XPS、BET、TPD表征了分子筛膜的物相、形貌、孔结构、表面元素组成和表面酸性，并通过甲醇与异丁烯液相反应体系实验考察了分子筛膜的催化性能．结果表明，等离子体处理能有效改善分子筛膜前驱体在基材表面的分散状况，减小了分子筛膜晶体的尺度，使晶体大小均匀，形成的膜致密、牢固．与采用常规方法合成的分子筛膜相比，等离子体辅助合成的分子筛膜对甲醇与异丁烯的反应有更好的催化活件．     

微乳液法合成LiFePO4 / C正极材料及其电化学性能

本文采用微乳液方法合成了纳米LiFePO₄ / C正极材料。制备样品分别用XRD和SEM进行表征，充放电测试其电化学性能。600 ℃制备样品为单一物相，平均粒径90 nm，在室温2.0～4.0 V (vs Li) 放电电压范围和15 mA·g^-1放电速率下，首次放电容量达到159 mAh·g^-1。制备样品同样展现良好的循环性能。在15 mA·g^-1速率下40次循环后，制备样品放电容量仍保持首次放电容量的98.9%。优异的电化学性能得益于样品颗粒的纳米尺寸、均匀分布以及表面碳层包覆提高了活性材料的电子电导率。     

Effect of dimethylaminoethyl methacrylate on the graft copolymerization of ethyl acrylate onto hydroxypropyl methylcellulose in aqueous medium

Graft copolymerization of an ethyl acrylate (EA) and dimethylaminoethyl methacrylate (DMAEMA) monomer mixture onto water-soluble hydroxypropyl methylcellulose was investigated with potassium persulfate (KPS) as the initiator in an aqueous medium. The effects of introducing DMAEMA onto the graft copolymerization and the properties of the resulting latex that was produced were studied systematically. The optimum conditions for the graft copolymerization in terms of percentage of grafting and grafting efficiency were determined. The graft copolymer was characterized by Fourier transform infrared spectra, elemental analyses, nuclear magnetic resonance, transmission electron microscopy, and dynamic light scattering methods. The results suggest that the introduction of the DMAEMA monomer clearly accelerates the initial rate of the graft copolymerization, whereas the grafting parameters decrease significantly with increasing amounts of DMAEMA. These results can be attributed to the relatively large size of the DMAEMA molecule, its redox reaction with KPS, its hydrophilicity in water, and its chain transfer effect. The equilibrium humidity adsorption behavior and acid solubility of graft the copolymer films were also studied.     

Frequency-domain measurement of the photodegradation process of fluorescein

The frequency-domain technique is applied to measure the photodegradation rate of fluorescein in aqueous solutions. The illuminating light is modulated, and the changes in fluorescence from the illuminated region are detected synchronously. A constant flow rate is imposed on the fluorescein solution to control the mass transport of fluorescein into the illuminated region. The fluorescence response is described by a model that assumes that photodegradation occurs from the triplet excited state. The predictions of the model are consistent with the observed variations in the fluorescence response with flow rate, modulation frequency and incident power. We discuss in this article how the dependence of the model parameters on experimental conditions can be used to infer the photodegradation rate as well as some of the details of the photodegradation mechanism. The results are consistent with the known mechanism of photodegradation of fluorescein. The frequency-domain technique gives a photodegradation rate of 53 s(-1) in an air-saturated solution and 37 s(-1) in solutions purged with argon gas.     

纳米SrTiO3对高铁酸盐电化学性能影响研究

Two ferrates, K₂FeO₄ and BaFeO₄, had been prepared and characterized by XRD, IR and SEM. The electrochemical tests of the samples were carried out in the voltage range of 0.8～2.0 V and current density of 0.5～3.0 mA·cm^-2. The results indicated that performance of Zn-BaFeO₄ battery was superior to that of Zn-MnO₂ and Zn-K₂FeO₄ batteries. Nanometer SrTiO₃ prepared by Sol-gel methode with different ratio was added to the BaFeO₄ cathode in order to improve the discharge performance. The discharge capacity of the BaFeO₄ cathode was increased from 224 mAh·g^-1 to 246 mAh·g^-1 by addition of 5% nanometer SrTiO₃. The reason of enhancing BaFeO₄ electrochemical performance was discussed.     

WxC-MCM-48催化剂的合成、表征及加氢脱硫催化性能

以正硅酸乙酯(TEOS)为硅源，十六烷基三甲基溴化铵(CTAB)为表面活性剂，仲钨酸铵为钨源，采用水热晶化法一步合成了不同钨含量(以Si、W物质的量比n_Si/n_W表示)的WO₃-MCM-48，然后经甲烷/氢气(V/V=1/4)混和气体程序升温还原碳化(TPC)，制备出了W_xC-MCM-48(x=1、2)催化剂，采用XRD、N₂吸附-脱附和NH₃-TPD对样品的结构进行了表征，用噻吩作为模型化合物，对W_xC-MCM-48催化剂的加氢脱硫催化活性进行了评价。结果表明，在一定钨含量的条件下，WO₃-MCM-48和W_xC-MCM-48样品仍然保持MCM-48的三维立方有序介孔结构，n_Si/n_W=30～15时，碳化钨的物相为W₂C；n_Si/n_W=7.5时，碳化钨为W₂C和WC物相，W_xC-MCM-48催化剂表现出了良好的加氢脱硫催化性能。     

单核铁(Ⅲ)双卟啉配合物在溶液中的构象平衡及其对环己烷羟化反应的催化活性的影响

合成及表征了一系列以柔韧碳氢链相连不同长度的ｐ／ｐ型单核铁（Ⅲ）双卟啉配合物，以可见光谱首次观察到该系列配合物在氯仿溶液中开放式及闭合式构象的平衡，发现６８０ｎｍ处吸收峰强度与这种构象平衡有关，烷氧链越长，该吸收峰强度越大．利用该类配合物模拟了细胞色素Ｐ４５０单加氧酶对环己烷的羟化作用，催化结果表明，在以分子氧为氧源及还原剂存在的温和条件下，该类配合物的催化活性显著高于单核铁卟啉（ＦｅＴＰＰＣｌ），随着柔韧碳氢链长度的增加，双卟啉的催化活性依次增加．高的催化活性与双卟啉配合物在溶液中的构象平衡，即闭合式构象引起的立体位阻及电子转移有关．     

金属络合物的相转移催化分析与分离

以可简单分离回收、可反复使用为目标，详细介绍了相转移催化的变化发展过 程．通过对溶剂的选择，使得催化剂选择性地溶解在某一液相中，而使产物溶解在 另一液相中，如水-有机两相催化体系；通过温度的变化，简单地实现了在较高温 度下反应为均相体系以提高催化剂的活性，而在较低温度下实现了催化剂与产物不 相溶使得催化剂得以简单分离，如温控型水-有机两相催化体系、氟-有机两相催化 体系、温控型含氟催化剂、温控型有机金属催化剂等．     

Synthesis and properties of niobia films derived from niobium pentaethoxide

The hydrolysis of niobium pentaethoxide precursor in the presence of triethylamine (TEA) is discussed. Three precursors with TEA/Nb(OEt)₅ mole ratios of 0.25, 0.4 and 0.8 were prepared. Niobia colloids with different appearance were obtained after autoclaving the above precursors at 250°C during 12 h. The surface roughness and microstructure of niobia films prepared with the colloids by spread coating method are strongly dependent on the TEA/Nb(OEt)₅ mole ratio. At a value of 0.4 TEA/Nb(OEt)₅ mole ratio, a niobia film with large surface roughness can be achieved. It is opaque and mechanically stable and has differently ordered needle microstructure. The crystalline structure and photoelectrochemical property of niobia film with the largest surface roughness were examined. The effect of CO₂ gas bubbling, reflux and addition of 2-methoxyethanol on the hydrolysis of Nb(OEt)₅ and the nature of the Nb₂O₅ films is also discussed.