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High-resolution photofragment translational spectro- scopy for the UV photodissociation of C_2._5I

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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 {2. sciences, State Key laboratory of {2. reaction dynamics, institute of chemistry, chinese academy of sciences, beijing 100080, china beijing National laboratory for {2. sciences State Key Laboratory of Molecular Reaction Dynamics Institute of Chemistry Chinese Academy of Sciences Beijing China

The photodissociation of ethyl iodide at 2.9.71, 2.1.73, 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*(2.1/2. and I(2.3/2. 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 C2.5, 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= 2..1% at 2.1.73 nm, 2..4% at 304.02.nm for the I* channel, and E int /E avl= 2..2. at 2.9.71 nm, 2..9% at 304.67 nm for the I channel, seem to be more reliable.

关键词： photofragment translational spectroscopy C_2._5I photodissociation vibrational state distribution energy partitioning dissociation energy

SILICA-SUPPORTED NICKEL AND ZIRCONIUM CATALYSTS FOR BRANCHED POLYETHYLENE

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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 {2. institute of chemistry chinese academy of {2. beijing 100080 china Stt. Key Lab. of Eng. Plastics Center for Molecular Sciences Chinese Academy of Sciences Beijing 100080 China

8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp_2.rCl_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_2.rCl_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_2.rCl_2 Silica supported catalysts Branched polyethylene

CHEMICAL STRUCTURE DEPENDENCE OF THE INTERNAL ENERGY CONTRIBUTION IN RUBBER ELASTICITY

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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 {2., 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)

PHASE STRUCTURE AND PROPERTIES OF EPOXY RESIN MODIFIED BY POLYSILOXANE BEARING PENDANT AMINO GROUPS

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chinese Journal of Polymer Science 2000年第2期18卷 133-138页

作者： Bing Zhang Xiang-luan Liu Ying Huang Center of molecular sciences,{2., chinese academy of sciences, beijing 100080, china 中科院化学所北京

Polysiloxane-modified epoxy resins were prepared through the reaction of epoxy resin with polydimethylsiloxanes bearing pendant N-(beta-aminoethyl)-gamma-aminopropyl groups. The morphology and properties of the cured epoxy resins modified by the polysiloxanes were investigated. It was found that the phase structure and properties of the cured epoxy resins depend mainly on the amino group content in the polydimethylsiloxane and the level of the modifier. The change of phase structure in the cured epoxy resin systems was responsible for the dramatic change in their mechanical and surface properties.

关键词： phase structure polysiloxane epoxy resin mechanical property

Microdynamics study on reaction of atom H and radical NH(X^3Σ)

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chinese Science Bulletin 1999年第11期44卷 1000-1003页

作者： XU Lijin, YAN Jimin and KONG Fan’aoState Key laboratory of molecular {2. dynamics , institute of chemistry, chinese academy of sciences , beijing 100080, china Corresponding author State Key laboratory of Moleclar reaction {2. Institute of Chemistry Chinese Academy of Sciences Beijing China

The dynamics of the H + NH→N + H2.reaction has been investigated by means of the 3-atom model quasiclassical trajectory approach. The LEPS potential energy surface is employed in the study, which is obtained from the... 详细信息

The dynamics of the H + NH→N + H2./sub> reaction has been investigated by means of the 3-atom model quasiclassical trajectory approach. The LEPS potential energy surface is employed in the study, which is obtained from the ab initio results and has an early saddle point in the minimum energy path. The results indicate that the reaction product H2./sub> is mainly scattered backward,and the reaction is found to occur via a direct channel. The product H2./sub> is in a cold excitation of rotational state, but has a hot vibrational excitation. Based on the potential surface and the trajectory analysis, the reaction mechanism has been explained successfully.

关键词： microdynamics of reaction quasiclassical trajectory calculation LEPS potential energy surface direct reaction.

A Detailed dynamics Study of the reaction CH_4+Cl→HCl+CH_3

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chinese Chemical Letters 1998年第8期9卷 771-774页

作者： Li Jin XU Xue Bin WANG Ji Min YAN Fan Ao KONG (State Key laboratory of molecular {2. dynamics, institute of chemistry,chinese academy of sciences, beijing 100080) State Key Lab. Molec. reaction D. Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

The detailed dynamics of the CH4+Cl→HCl+CH3 reaction has been investigated by means of the quasiclassical trajectory approach. The properties analyzed can be interpreted in terms of the main topological featUres of the potential energy surface used. on the basis of the theoretical results, two reaction channels are proposed: one is a direct channel and the other is a complex one.

关键词： quasiclassical trajectory calculation LEPS potential energy surface

Interfacial behaviors of PMMA-PEO block copolymers at the air/water interface

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Science china chemistry 2005年第6期48卷 567-573页

作者： CHENG Caixia1, JIAO Tifeng2. TANG Rupei1, LIU Minghua2.& XI Fu1 1. State Key laboratory of Polymer Physics and chemistry, Joint laboratory of Polymer Science and Materials, institute of chemistry, chinese academy of sciences, beijing 100080, china 2. CAS Key laboratory of Colloid and Interface Science, institute of chemistry, chinese academy of sciences, beijing 100080, china State Key laboratory of Polymer Physics and chemistry Joint Laboratory of Polymer Science and Materials Institute of Chemistry Chinese Academy of Sciences Beijing China CAS Key laboratory of Colloid and Interface Science Institute of Chemistry Chinese Academy of Sciences Beijing China

Diblock copolymer of PMMA2.1-b-PEO114 and triblock copolymer of PMMA12.-b- PEO2.7-b-PMMA12. were synthesized and their interfacial properties at the air-water interface were investigated, where both blocks of polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) are surface active but the former is soluble in water while the latter is not. Both the block copolymers could form monolayers with two obvious transition regions. The first transition point is around 10 mN/m, which could be assigned to the pancake-brush change of the PEO chains. The other is around 18 mN/m, which could be ascribed to the condensed packing of PMMA. The surface morphological changes during the compression of the Langmuir monolayers are inves-tigated by using the AFM and SEM methods for the films deposited at different surface pressure or molecular areas. At a lower surface pressure, a typical morphology of PEO-con- taining lipopolymers is observed. Upon compression, sphere-dominant morphologies were observed. While the diblock copolymer is easy to folding, the triblock copolymer is in favor of formation of circular domains through vesiculation.

关键词： PMMA-PEO, block copolymers, monolayer, Langmuir-Blodgett films, AFM.

Effect of concentration on surfactant micelle shapes——A molecular dynamics study

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Science china chemistry 2005年第5期48卷 470-475页

作者： GAO Jian1,2. GE Wei1 & LI Jinghai1 1. Multiphase reaction laboratory, {2. of Process Engineering, chinese academy of sciences, beijing 100080, china 2. Graduate School of The chinese academy of sciences, beijing 100085, china Multiphase reaction laboratory Institute of Process Engineering Chinese Academy of Sciences Beijing China Graduate School of The chinese academy of sciences Beijing China

Many aspects of the behavior of surfactants have not been well understood due to the coupling of many different mechanisms. Computer simulation is, therefore, attractive in the sense that it can explore the effect of different mechanisms separately. In this paper, the shapes, structures and sizes of sodium dodecylbenzenesulfonate (SDBS) micelles under different con-centrations in an oil/water mixture were studied via molecular dynamics (MD) simulations using a simplified atomistic model which basically maintains the hydrophile and lipophile properties of the surfactant molecules. Above the critical micellar concentration (cmc), surfactant molecules ag-gregate spontaneously to form a wide variety of assemblies, from spherical to rodlike, wormlike and bilayer micelles. Changes in their ratios of the principle moments of inertia (g1/g3, g2.g3) in-dicated the transition of micelle shapes at different concentrations. The aggregation number of micelle is found to have a power-law dependence on surfactant concentration.

关键词： surfactant, MD simulation, sodium dodecylbenzenesulfonate, micelle shape.

SOLID PHASE TRANSITION OF SYNDIOTACTIC POLYSTYRENE IN SUPERCRITICAL CO_2

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chinese Journal of Polymer Science 2002年第3期20卷 191-196页

作者： Yu-ying Li Jia-song He State Key laboratory of Engineering Plastics, Center for molecular Science,{2. chinese academy of sciences, beijing 100080 china Center for molecular Science Institute of Chemistry Chinese Academy of Sciences State Key Laboratory of Engineering Plastics 北京 100080

Solid phase transition of the a form crystals to the 3 form crystals in syndiotactic polystyrene (sPS) samples has occurred in supercritical CO2. This transformation is different from those detected under other conditions. The effects of some factors (e.g. time, temperature, and pressure) on the solid phase transformation of sPS in supercritical CO2.were analyzed in detail. Experimental results show that longer time, higher temperature or higher pressure favors the transformation of the a form crystals to the beta form crystals.

关键词： solid phase transition syndiotactic polystyrene supercritical CO2