检索结果-南通市图书馆

SILICA-SUPPORTED NICKEL AND ZIRCONIUM CATALYSTS FOR BRANCHED POLYETHYLENE

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2003年第4期21卷 453-458页

作者：孙文华 State Key laboratory of Engineering Plastics The Center for molecular sciences institute of chemistry chinese academy of sciences beijing 100080 china State Key laboratory of Engineering Plastics The Center for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp_2ZrCl_2) were supportedsimultaneously on silica to produce branched polyethylene successfully by combined polymerization. The supportedpolymerization results showed that the molecular weight of polyethylene increased while the molecular weight distributionbecame wider and the molecular chains of oligomers remaning in the final solution became shorter as compared to theoligomers obtained in polymerization processes with pure 8-aminoquinoline nickel dichloride catalysis, as well as theCp_2ZrCl_2 and nickel combination system. With decreasing amount of Ni catalyst in the supported catalyst, the molecular chains of oligomers in the resulting solution became shorter, while α-olefin selectivity increased.

关键词： 8-Aminoquinoline nickel dichloride, Cp_2ZrCl_2 Silica supported catalysts Branched polyethylene

CHEMICAL STRUCTURE DEPENDENCE OF THE INTERNAL ENERGY CONTRIBUTION IN RUBBER ELASTICITY

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2001年第5期19卷 447-449页

作者： Juan Sun Xiao-zhen Yang Polymer Physics laboratory Center for molecular sciences, institute of chemistry chinese academy of sciences beijing 100080 china 中科院化学所高分子物理及化学国家重点实验室北京

Conformational elasticity theory recently developed has been used to explore the internal energy contribution to the elastic force f(e)/f as a function of strain for poly(cis-1,4-isoprene) and poly(trans-1,4-isoprene). Calculated f(e)/f values are in good agreement with those obtained experimentally. Results show that behavior of f(e)/f is mainly contributed by chemical structure, or intramolecular interaction, supporting the experimental observations, and that the internal energy contribution is strain dependent.

关键词： conformational elasticity theory internal energy contribution poly(cis-1,4-isoprene) poly(trans-1,4-isoprene)

SYNTHESIS AND CHARACTERIZATION OF NEW STABILIZERS WITH OPTIMAL molecular WEIGHT

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2001年第4期19卷 341-350页

作者： Jiang-qing Pan institute of chemistry chinese academy of sciences, beijing 100080 china 中科院化学所北京

Over 2 x 10(8) tons of polymers are produced every year, and a large portion of polymers faces the degradation problem. There are many effective methods to protect polymers against degradation and the addition of stabilizers to polymer remains the most convenient and effective way of enhancing polymer life and performance. In this article, a series of effective stabilizers with optimal molecular weight (MW), including common, monomeric and polymeric stabilizers (antioxidant and light stabilizer) were synthesized using isocyanation, controlled isocyanation, hydrosilylation, epoxide addition, macroreaction of stabilizing functional compounds and polymerization of monomeric stabilizers. The structure and performance of these new stabilizers were characterized by using IR, NMR, MS, UV-spectra, XPS and elemental analysis. The current development of stabilizer synthesis was also reviewed.

关键词： preparation of stabilizer antioxidant hindered amine light stabilizer isocyanation hydrosilylation

The design and synthesis of fused thiophenes and their applications in organic field-effect transistors

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2010年第4期53卷 779-791页

作者： LIU Ying, YU Gui & LIU YunQi beijing national laboratory for molecular sciences, Key laboratory of Organic Solids, institute of chemistry, chinese academy of sciences, beijing 100190, china beijing national laboratory for molecular sciences Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences Beijing China

Fused thiophenes refer to oligothienoacenes in which several thiophenes are coupled together via twoor multi-positions and their derivatives. The synthesized organic semiconductors based on fused thiophenes exhibit excellent field effect properties due to their efficient intermolecular S…S interactions and π…π stacking. The performances of organic field-effect transistors (OFETs) depend not only on the materials but also on the devices. Such factors which influence the device performances as device structures, fabrication technologies and interface engineering are extensively investigated based on the fused thiophenes. Searching for new organic semiconductors and improving the device fabrication technologies are two major issues in the development of OFETs.

关键词： fused thiophenes oligothienoacenes organic field-effect transistors device performance

High-resolution photofragment translational spectro- scopy for the UV photodissociation of C_2H_5I

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2007年第4期50卷 476-482页

作者： BI WeiBin, XU XiLing, HUANG JianGou, XIAO DaoQing & ZHU QiHe beijing national laboratory for molecular sciences, State Key laboratory of molecular Reaction Dynamics, institute of chemistry, chinese academy of sciences, beijing 100080, china beijing national laboratory for molecular sciences State Key Laboratory of Molecular Reaction Dynamics Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

The photodissociation of ethyl iodide at 279.71, 281.73, 304.02 and 304.67 nm has been studied on our new mini-photofragment translational spectrometer with a total flight path of only 5 cm. Some vibra-tional peaks are firstly resolved in the TOF spectra of I*(2P1/2) and I(2P3/2) channels. These vibrational peaks are assigned to the excitation states (ν2 = 0, 1, 2,…) of the umbrella mode (ν2, 540 cm-1) of the photofragment C2H5, and the distribution of the vibrational states is obtained. The dissociation energy has been determined to be D0(C-I)=2.314 ± 0.03 eV. The energy partitioning of the available energy (Eavl=ET+Eint=ET+EV,R) calculated from our experimental data E int /E avl= 22.1% at 281.73 nm, 22.4% at 304.02 nm for the I* channel, and E int /E avl= 25.2% at 279.71 nm, 25.9% at 304.67 nm for the I channel, seem to be more reliable.

关键词： photofragment translational spectroscopy C_2H_5I photodissociation vibrational state distribution energy partitioning dissociation energy

A Dye-sensitized Nanocrystalline Solid State Photovoltaic Cell

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 2000年第9期11卷 813-814页

作者： Dong She ZHANG Xu Rui XIAO laboratory of photochemistry, Center for molecular sciences, institute of chemistry, chinese academy of sciences, beijing, 100080 laboratory of Photochemistry Center for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences

A new type of dye-sensitized nanocrystalline solid state photovoltaic cell based on the wide band gap n-TiO2/p-CuI heterojunction was fabricated. Tetra-carboxyphenyl porphyrine (TPP-(COOH)(4)), squarylium cyanine derivative (SQ-(CH2),(SO3Py+)-Py-.) and ruthenium bipyridyl complex (RuL2(NCS)(2)) were used as photosensitizers. Larger photocurrents and photovoltages were shown in the cell sensitized by ruthenium bipyridyl complex and can be further increased by intercalation of a TiO2 thin underlayer.

关键词： nanocrystalline TiO2 electrode dye sensitization solid state cell

PREPARATION AND PROPERTIES OF ETHYL-CYANOETHYL CELLULOSE/POLYACRYLIC ACID COMPOSITE FILMS WITH REFLECTION COLORS

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2001年第3期19卷 277-282页

作者： Yong Huang institute of chemistry, chinese academy of sciences, beijing 100080 china laboratory of Cellulose and Lignocellulosics chemistry Guangzhou institute of chemistry chinese academy of sciences, Guangzhou 510650, china 中科院化学所北京

Ethyl-cyanoethyl cellulose [(E-CE)C]/acrylic acid (AA) becomes a cholesteric liquid crystalline solution withvivid colors when the (E-CE)C concentration is 42 wt%～52 wt%. (E-CE)C/polyacrylic acid (PAA) composites withcholesteric structure were prepared by polymerzing AA in (E-CE)C/AA liquid crystalline solutions. The layers of orderedpolymer chains in the cholesteric phase were inclined during polymerization and the degree of the inclination depended onthe polymerization temperature and the concentration of the solution before polymerization. The cholesteric structure in thecomposites could not be changed when temperature was lower than 100℃. Cross-linking of the PAA in compositesimproved their water-resistance. The cholesteric order of the composites without cross-linking was destroyed when theywhere immersed in water. The color derived from the selective reflection of the cholesteric phase of the cross-linkedcomposites turned from blue to red after the composites absorbed water. The color of the composites could be returned to theoriginal one when the absorbed water was removed from the swollen composites.

关键词： Cholesteric structure Composites Selective reflection Liquid crystalline solutions

Recognition of amino acids and anions by a Zn(Ⅱ)-methylazacalix[4]pyridine complex

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2009年第10期52卷 1639-1645页

作者： GONG HanYuan, WANG DeXian, HUANG ZhiTang & WANG MeiXiang beijing national laboratory for molecular sciences, CAS laboratory of molecular Recognition and Function, institute of chemistry, chinese academy of sciences, beijing 100190, china beijing national laboratory for molecular sciences CAS Laboratory of Molecular Recognition and Function Institute of Chemistry Chinese Academy of Sciences Beijing China

As a powerful macrocyclic host molecule with unique conformation and cavity structure that are fine-tuned by the bridging nitrogen atoms, methylazacalix[4]pyridine (MACP-4) has been shown to selectively recognize Zn2+ and form stable Zn(Ⅱ)-MACP-4 complexes both in solid state and solution with an association constant up to 5.97 (logKs). The molecular recognition of Zn(Ⅱ)-MACP-4 complexes towards various amino acids and anions with different geometry was investigated by using the spectral titration methods and X-ray analysis. The Zn(Ⅱ)-MACP-4 complex was found to recognize the 17 amino acids tested with the association constant up to 3.97 (logKs). On the other hand, the Zn(Ⅱ)-MACP-4 complex selectively interacted with anions and the maximum association constant of 3.9 (logKs) was obtained.

关键词： Zn(Ⅱ)-MACP-4 complex amino acids anions recognition

Study on the atmospheric photochemical reaction of CF_3 radicals using ultraviolet photoelectron and photoionization mass spectrometer

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2008年第4期51卷 316-321页

作者： YAO Li1,2, DU Lin1,2, YIN Shi1,2 & GE MaoFa1 1 beijing national laboratory for molecular sciences (BNLMS), State Key laboratory for Structural chemistry of Unstable and Stable Species, institute of chemistry, chinese academy of sciences, beijing 100080, china 2 Graduate University of chinese academy of sciences, beijing 100080, china beijing national laboratory for molecular sciences (BNLMS) State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China

A study of the atmospheric photochemical reaction of CF3 radical with CO and O2 was performed by using a homemade ultraviolet photoelectron spectrometer-photoionization mass spectrometer (PES- PIMS). The electronic structures and mechanism of ionization and dissociation of CF3OC(O)OOC(O)- OCF3 were investigated. It was indicated that the two bands on the photoelectron spectrum of CF3OC(O)OOC(O)OCF3 are the result of ionization of an electron from a lone pair of oxygen and a fluo- rine lone pair of CF3 group. The outermost electrons reside in the oxygen lone pair. The experimental and theoretical first vertical ionization energy is 13.21 and 13.178 eV, respectively, with the PES and OVGF method. They are in good agreement. The photo ionization and dissociation processes were discussed with the help of theoretical calculations and PES-PIMS experiment. After ionization, the parent ions prefer the dissociation of the C-O bond and giving the fragments CF3OCO+ and CF3+. It demonstrated that the ultraviolet photoelectron and photoionization mass spectrometer could be ap- plied widely in the study of atmospheric photochemical reaction.

关键词： photochemical reaction CF3 radical ultraviolet photoelectron and photoionization mass spectroscopy transient species