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当在Sharpless试剂中加入催化量的金属氢化物和硅胶后, 烯丙醇的不对称环氧化反应时间大为缩短, 而化学和光学产率不受影响。着重讨论了氢化钙和硅胶对Sharpless烯丙醇不对称环氧化的作用。 相似文献
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《Composite Interfaces》2013,20(4-6):447-455
Lanthanide doped sol–gel glasses are an attractive type of luminescent material which can be processed at ambient temperatures. However, it is very difficult to obtain a uniform distribution of the complexes in glass materials because of their strong tendency to cluster formation. This problem can be solved by covalently linking of lanthanide complexes to silica matrix. In our work such materials were obtained by the sol–gel method of hydrolysis and polycondensation of tetramethoxysilane with europium complexes containing trimethoxysilyl groups. For this purpose we synthesized a novel ligand — (N-3-trimethoxysilylpropyl)-N′-1,10-phenanthroline-5-yl-thiocarbamide — and corresponding complexes [Eu(tta)3phen′]Cl3 and [Eu(pta)3phen′]Cl3. Our approach enabled us to simplify the synthetic procedure. A number of uniform samples showing intense luminescence have been obtained and the concentration dependence of their luminescence has been studied. 相似文献
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《Composite Interfaces》2013,20(5-7):505-512
The Al(OH)3/acrylic copolymer latexes were synthesized through the emulsion polymerization of acrylic monomers, butyl acrylate and 2-ethylhexyl acrylate in the presence of surface-functionalized Al(OH)3 filler particles. The polymerization was stabilized by polyoxyethylene (50) nonyl phenyl ether (NP-1050, nonionic surfactant) and ammonium (POE) alkyl aryl ether sulfate (EU-S133D, anionic surfactant) to produce stable composite latexes. The improved compatibility of Al(OH)3 surface with acrylic monomers was achieved by the modification with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS). Transmission electron microscopy showed that nano-sized Al(OH)3 particles were slightly agglomerated in the copolymer latex. When pristine Al(OH)3 was used as a filler or γ-MPS-modified Al(OH)3 particles were added above 30 wt% with respect to monomers, unstable latexes were obtained, which were partially precipitated out on standing for prolonged time. The flame retardation effect was not apparent with the incorporation of Al(OH)3 in the latexes by 30 wt% as shown by LOI test. 相似文献
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采用流变学法系统地考察了部分水解聚丙烯酰胺(HPAM)/Cr(III)交联体系的 反应动力学。HPAM溶液的粘性模量G”大于弹性模量G’,且其数值随时间不发生变 化,体系为粘性溶液。而HPAM/Cr(III)体系的G’和G”的数值都随时间变化,G” 在反应开始阶段大于G’,当反应进行一段时间后,G’超过G”占据主要地位,体 系成为弹性体系。交联过程可分为三个阶段:第一上升阶段,平缓上升阶段和第二 上升阶段。利用G’~ t曲线可以推测反应机理。实验发现成胶速率随反应物HPAM 和Cr(III)的浓度的增加而增加,而成胶时间缩短。在羧基浓度过量的情况下,交 联反应对Cr(III)浓度的反应级数是1。凝胶的有效弹性交联密度随聚合物浓度的增 加而增,且随凝胶反应的进行而增加。凝胶的交联点间的平均分子量随Cr(III)浓 度的增加和交联反应的进行而下降。 相似文献
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自溶液中的吸附XIII.硅胶自环己烷-正脂肪醇和水-正脂肪醇中吸附TRITONX-100 总被引:1,自引:0,他引:1
测定了硅胶和活性炭自水、环己烷和正丁醇中吸附TRITON X-100的等温线,提出了TRITON X-100在硅胶-环己烷界面上形成单分子层,在硅胶-水界面上形成双分子层的吸附模型,测定了硅胶自环己烷-正脂肪醇(C2,C4,C8和C12)和水-正脂肪醇(C2和C4)混合溶剂中吸附TRITON X-100的等温线,自环己烷-正脂肪醇中的吸附时,醇的烃链越短,浓度越大,降低TRITON X-100的吸附作用越显著.自水-正脂肪醇中吸附时,正丁醇降低TRITON X-100的吸附作用比乙醇时更显著,但当TRITON X-100的浓度较低时,正丁醇(0.5mol.dm[-3])的存在却使TRITON X-100的吸附有所增加。 相似文献
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将以Euler方法为基础的MF PPM(Piecewise-Parabolic Method)程序和以Lagrange方法为基础的DEFEL(2-D Finite Elements Code,二维流体弹塑性动力有限元)程序,根据压力和法向速度连续准则进行耦合,发展了基于Level Set的GEL(Ghost-Fluid Euler-Lagrange)方法。该方法在处理大变形流场与小变形结构以及复杂流动与多物体相互作用等问题具有优越性。通过二维算例的计算结果与文献比较,检验了GEL方法和耦合程序的正确性,并对球形和椭球封头的爆炸容器进行了数值模拟,通过与实验结果的比较分析,表明本研究程序可以比较好地处理内爆引起的壳体流固耦合问题。 相似文献