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Science china chemistry 2007年第6期50卷 737-745页

作者： XU XiaoJuan1,2. XIAO JiJun1, HUANG Hui3. LI JinShan3.& XIAO HeMing1 1 Department of chemistry, Nanjing university of Science and Technology, Nanjing 2.0094,{2. 2.Department of chemistry, Yancheng Teacher’s college, Yancheng 2.4002.{2. 3.Institute of Chemical Materials,{2. Academy of engineering Physics, Mianyang 62.900,{2. Department of chemistry Nanjing University of Science and TechnologyNanjing 210094China Department of chemistry Yancheng Teacher''s CollegeYancheng 224002China Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900

Five polymer bonded explosives(PBXs)with the base explosive epsilon-CL-2.(hexanitrohexaazaisowurtzi-tane),the most important high energy density compound(HEDC),and five polymer binders(Estane 5703.GAP,HTPB,PEG,and F_(2.14))were *** dynamics(MD)method was employed to investigate their binding energies(E_(bind))2./PEG 2./ Estane5703.≈ epsilon-CL-2./GAP 2./HTPB 2./F_(2.14).By pair correlation function g(r)analyses,hydrogen bonds and vdw are found to be the main interactions between the two *** elasticity and isotropy of PBXs based epsilon-CL-2. can be obviously improved more than pure epsilon-CL-2. *** is not by changing the molecular structures of epsilon-CL-2. for each binder to affect the *** safety and energetic properties of these PBXs are mainly influenced by the thermal capability(C_p^(deg))and density(p)of binders,respectively.

关键词： high energy density material (HEDM), hexanitrohexaazaisowurtzitane (CL-2.), polymer bonded explosives (PBXs), molecular dynamics (MD), compatibility, safety properties, mechanical properties, energetic properties

Preparation of well-defined polystyrene/silica hybrid nanoparticles by ATRP

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Science china chemistry 2008年第1期51卷 51-57页

作者： OU BaoLi1,2.LI DuXin2.1 college of {3. and Chemical {2.,Hunan {3. of Science and Technology,Xiangtan 4112.1, china 2.State Key Laboratory of Powder Metallurgy,Central South {3.,Changsha 410083. china 1. college of chemistry and Chemical {2. Hunan University of Science and Technology Xiangtan 411201 China 2. State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

Immobilization of the atom transfer radical polymerization (ATRP) macroinitiators at the silica nanoparticle surfaces was achieved through surface modification with excess toluene-2.4-diisocynate (TDI), after which the residual isocyanate groups were converted into ATRP macroinitiators. Structurally well-defined polystyrene chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined, densely grafted outer polystyrene by ATRP, which was initiated by the as-synthesized silica-based macroinitiator. FTIR, NMR and gel permeation chro-matography (GPC) were used to characterize the polystyrene/silica hybrid particles.

关键词： silica nanoparticles surface modification atom transfer radical polymerization polystyrene hybrid particle

Preparation of polystyrene/silica nanocomposites by radical copolymerization of styrene with silica macromonomer

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Science china chemistry 2007年第3期50卷 385-391页

作者： OU BaoLi1,2.& LI DuXin2.1 college of {3. and Chemical {2., Hunan {3. of Science and Technology, Xiangtan 4112.1, china 2.State Key Laboratory of Powder Metallurgy, Central South {3., Changsha 410083. china 1. college of chemistry and Chemical {2. Hunan University of Science and Technology Xiangtan 411201 China 2. State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

A two-stage process has been developed to generate the silica-based macromonomer through surface-modification of silica with polymerizable vinyl groups. The silica surfaces were treated with excess 2.4-toluene diisocynate (TDI), after which the residual isocyanate groups were converted into polymerizable vinyl groups by reaction with hydroxypropylacrylate (HPA). Thus, polystyrene/silica nanocomposites were prepared by conventional radical copolymerization of styrene with silica macromonomer. The main effecting factors, such as ratios of styrene to the macromonomer, together with polymerization time on the copolymerization were studied in detail. FTIR, DSC and TGA were utilized to characterize the nanocomposites. Experimental results revealed that the silica nanoparticles act as cross-linking points in the polystytene/silica nanocomposites, and the glass transition temperatures of the nanocomposites are higher than that of the corresponding pure polystyrene. The glass transition temperatures of nanocomposites increased with the increasing of silica contents, which were further ascertained by DSC.

关键词： silica nanoparticles surface modification styrene radical copolymerization nanocomposites

SYNTHESIS AND PROPERTIES OF LIQUID CRYSTAL POLYSILOXANES WITH MESOGENIC STILBENE SIDE GROUPS

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Chinese Journal of Polymer Science 2000年第2期18卷 95-99页

作者： Dong Zhang Yan-tao Zhu Da-hui Zhao Xin-hua Wan Qi-feng Zhou Department of Polymer Science & engineering, college of {2.,{3., Beijing 100871, china peking Univ Coll Chem Dept Polymer Sci & Engn Beijing 100871 Peoples R China

A variety of mesomorphic side-chain polysiloxanes were synthesized by using hydrosilylation reaction with dicyclopentadienylplatinum(II) (DPPC) as the catalyst. The mesogenic groups are derivatives of stilbene with cyano or nitro tail groups. The products were characterized by DSC, X-ray diffraction and polarizing optical microscopy (POM). All the polymers were found to have relatively low T-g and can form a smectic liquid crystal phase.

关键词： liquid crystal polymer polysiloxane

Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of Shenzhen in summer and in winter

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Science china chemistry 2006年第5期49卷 466-474页

作者： NIU Yuwen1,2.HE Lingyan1,2.HU Min2.ZHANG Jing2.& ZHAO Yunliang2.1. Shenzhen Graduate School of peking university,Shenzhen 518055,china 2. State Joint Key Laboratory of Environmental Simulation and Pollution Control,{2. of Environmental Sciences,peking university,Beijing 100871,china 1. Shenzhen Graduate School of peking university Shenzhen 518055 China 2. State Joint Key Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences Peking University Beijing 100871 China

Two field measurements for atmospheric fine particles were conducted in Baoan district of Shenzhen during the summer and winter in 2.04. Totally 3. sets of 2. h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal varia- tions and secondary pollution characteristics of fine particles during the sampling periods were dis-cussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in Shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 3. μg·m-3.and 57 μg·m-3. respectively, and those in winter were 99 μg·m-3.and 13. μg·m-3. respec-tively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 13.%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in Shenzhen. During the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. During the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol compo-nents in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from South china Sea in summer, and the air quality was good. The prevailing wind in winter was from china's Mainland to the north, and the polluted air mass led to poor air quality.

关键词： PM2.5, mass concentration, secondary pollution, seasonal variation, Shenzhen.

Sensing characterization of Sn/In/Ti nanocomplex oxides for CO, CH_4 and NO_2

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Science china(Technological Sciences) 2007年第1期50卷 18-26页

作者： BAI ShouLi1, TONG ZhangFa2. LI DianQing1, HUANG XiaoWei3. LUO RuiXian1 & CHEN AiFan1 1 State Key Laboratory of Chemical Resource engineering, Beijing university of Chemical Technology, Beijing 10002.,{2. 2.School of {3. and Chemical engineering, Guangxi university, Nanning 53.004,{2. 3.college of Biochemical engineering, Beijing Union university, Beijing 10002.,{2. 1. State Key Laboratory of Chemical Resource engineering Beijing University of Chemical Technology Beijing 100029 China 2. School of chemistry and Chemical engineering Guangxi University Nanning 530004 China 3. college of Biochemical engineering Beijing Union University Beijing 100023 China

The nanocomplex oxides of Sn-In and Sn-In-Ti were prepared by controlled co-precipitation method as sensing materials of semiconductor gas sensors for detection of CO, CH4 and NO2. Through manipulating the Sn/In cation ratio, metal salt total concentration, precipitation pH value and aging time, the nanocrystalline powders were successfully derived with chemical homogeneity and superior thermal stability, compared with the single component oxides. The particle size and morphology, surface area, and thermal and phase stabilities were characterized using TEM, TG-DTA, BET and XRD. The sensing tests showed that the Sn-In com-posites exhibit high sensitivity and selectivity for CO and NO2. The introduction of TiO2.enhanced CH4 sensitivity and selectivity, particularly, additives of Pd and Al2.3.as a dopant and surface modification greatly enhanced the sensing properties. The sensitivity depended on the composition of composites, calcination temperature and operating temperature. The optimal values were (2.%In2.3. 75%SnO2.-2.%TiO2.for ternary composite, 600 and 3.0℃, respectively. Temperature-programmed de-sorption (TPD) studies were employed to explain the gas adsorption behavior dis-played by the surface of nanocomposites and X-ray photoelectron spectroscopic (XPS) analysis was used to confirm the electronic interactions existing between oxide components. The sensing mechanism of the nanocomposites was attributed to chemical and electronic synergistic effects.

关键词： SnO2.In2.3.TiO2 nanocomposites CO NO2 CH4 gas sensing

Homochiral expression of proteins:a discussion on the natural chirality related to the origin of life

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Science china chemistry 2010年第4期53卷 792-796页

作者： HU PingPing1,2. PENG Li2. ZHEN ShuJun3. CHEN LiQiang2. XIAO SaiJin1 & HUANG ChengZhi1,3.1Key Laboratory on Luminescence Real-Time Analysis, Ministry of Education {3. of chemistry and Chemical {2., Southwest {3., Chongqing 400715, china 2.0} of Life Science, Southwest {3., Chongqing 400715, china 3.3. of Pharmaceutical Sciences, Southwest {3., Chongqing 400715, china 1. Key Laboratory on Luminescence Real-Time Analysis Ministry of Education Southwest University Chongqing 400715 China2. College of Life Science Southwest University Chongqing 400715 China4. College of Chemistry and Chemical Engineering Southwest University Chongqing 400715 China3. College of Pharmaceutical Sciences Southwest University Chongqing 400715 China

Homochirality in life has always been a driving force in scientific research and natural exploration. It has not been satisfactorily explained, and systematic investigations are necessary. This paper reported a homochiral expression of proteins dependent on the stirring direction of growing media. By controlling the stirring direction clockwise (CW) and anticlockwise (ACW) of the culture medium, proteins with distinct secondary structures were obtained, and D-amino acid may be included in the protein cultured with the stirring direction of ACW. Considering the effect of force fields, which might affect the process of folding and refolding of cellular protein in this report, the control of force fields might be a good way to prepare asymmetric drugs, and the rotational direction of the earth is possibly related to the chirality in primitive life molecules.

关键词： homochirality chiral expression prion protein fluorescence

SYNTHESIS AND BIOTECHNOLOGICAL APPLICATIONS OF VINYL POLYMERINORGANIC HYBRID AND MESOPOROUS MATERIALS

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Chinese Journal of Polymer Science 2000年第1期18卷 1-7页

作者： Yen Wei Kun-yuan Qiu Department of chemistry, Drexel university, Philadelphia, Pennsylvania 19104, USA Department of Polymer Science and {2.,{3., Beijing 100871, china Drexel Univ Dept Chem Philadelphia PA 19104 USA peking Univ Dept Polymer Sci & Engn Beijing 100871 Peoples R China

We describe the sol-gel synthesis of a new family of organic-inorganic hybrid materials, in which various vinyl polymers are covalently bonded to and uniformly distributed in inorganic oxide matrices. The materials can be tailored to have both good toughness and hardness while maintaining excellent optical transparency. Doping the sol-gel metal oxides with optically active compounds such as D-glucose results in new optical rotatory composite materials. Removal of the dopant compounds from the composites affords mesoporous oxide materials; which represents a new, nonsurfactant-templated route to mesoporous molecular sieves. We have successfully immobilized a series of enzymes and other bioactive agents in mesoporous materials. Catalytical activities of the enzyme encapsulated in mesoporous materials were found to be much higher than those encapsulated in microporous materials.

关键词： vinyl polymer-inorganic hybrid materials mesoporous materials sol-gel process biotech-nological applications

Controlled free radical polymerization of styrene initiated from the alkoxyamine-functionalized silicon surface

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Science china chemistry 2005年第5期48卷 449-458页

作者： CHEN Zhijun1, ZHOU Sikai1, LU Wenzhong1, FANG Shaoming1, JIANG Xiqun2.& YANG Changzheng2.1. college of Materials and Chemical {3., Zhengzhou {2. of Light Industry, Zhengzhou 450002. china 2. Laboratory of Mesoscopic Material Science and Department of Polymer Science & {3., college of chemistry & Chemical {3., Nanjing {2., Nanjing 2.0093. china 1. college of Materials and Chemical engineering Zhengzhou University of Light Industry 450002 Zhengzhou China 2. Laboratory of Mesoscopic Material Science and Department of Polymer Science & engineering College of Chemistry & Chemical Engineering Nanjing University 210093 Nanjing China

We describe a new method of fabricating a brush-like polystyrene layer anchored on the surface of the silicon substrate, which involves three steps, namely (i) the attachment of 3.methacryloxypropyltrimethoxysilane onto the silicon surface; (ii) the reaction of vinyl moiety at another extremity of the anchored 3.methacryloxypropyltrimethoxysilane to 4-Hydroxyl-2. 2. 6, 6-tetramethyl-1-piperidinyloxy (HTEMPO?) catalyzed by azobisisobutyronitrile (AIBN); (iii) living free radical grafting polymerization of styrene in the presence of HTEMPO?. The controllable living free radical polymerization permits accurate control of both the molecular weight and the polydispersity. X-photoelectron spectroscopy measurement proved that the alkoxyamine initiator layer forms on the silicon surface. XPS and Ellipsometry measurements showed that the poly-styrene chains were covalently anchored onto the silicon surface. The thickness of the grafted polymer layer can be accurately manipulated by altering the polymerization time. The new method allows synthesizing random copolymer and block copolymers by the sequential growth of monomers from the substrate surface.

关键词： polymer brush, controlled living free radical polymerization, thickness, atomic force microscopy, 3.methacryloxypropyltrimethoxysilane.

Crystal Structure of 1,1-Dichloro-4-formyl-3.methyl-1a-phenyl-1a,2.3.4-tetrahydro-1H-azirino〔1,2.a〕〔1,5〕benzodiazepine(C18H16Cl2.2.)

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Chinese Journal of Structural chemistry 1999年第4期 31-34页

作者： XU JiaXi\ ZHANG XinYu\ JIN Sheng (college of chemistry and {2.{3., peking university, Beijing 100871)

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关键词： crystal structure azirino1 2.1 5benzodiazepine 1