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Chinese Journal of Polymer Science 2000年第5期18卷 469-472页

作者： Jie-bin Pang Kun-yuan Qiu Yen Wei Department of Polymer Science and engineering, college of {2. and molecular engineering, peking university, beijing 100871, China. Department of {2., Drexel university, Philadelphia, Pennsylvania 19104, USA. 北京大学北京 Drexel university 美国

Mesoporous poly(styrene-co-maleic anhydride)/silica hybrid materials have been prepared. The synthesis was achieved by the HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and styrene-maleic anhydride copolymer in the presence of 3-aminopropyl triethoxysilane (APTES) as a coupling agent and citric acid as a nonsurfactant template or pore-forming agent, followed by ethanol extraction. Characterization results from nitrogen sorption isotherms and powder X-ray diffraction indicate that polymer-modified mesoporous materials with large specific surface areas (e.g. 900 m(2./g) and pore volumes (e.g. 0.6 cm(3)/g) could be prepared. As the citric acid concentration is increased, the specific surface areas, pore volumes and pore diameters of the hybrid materials increase.

关键词： mesoporous hybrid material poly(styrene-co-maleic anhydride)/silica citric acid nonsurfactant template sol-gel process

Solvation effects on brain uptakes of isomers of ^(99m)Tc brain imaging agents

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Chinese Science Bulletin 2002年第21期47卷 1786-1791页

作者： JIA Hongmei, MA Xiaohui, WANG Cunxin & LIU Boli1. Department of chemistry, beijing Normal {2., beijing 100875, China 2. Center for Biomedical engineering, beijing Polytechnic {2., beijing 10002., China Department of chemistry Beijing Normal University Beijing 100875 China Center for Biomedical engineering Beijing Polytechnic University Beijing 100022 China

Analysis of electrostatic hydration free energies of the isomers of the 99mTc-BAT and 99mTc-DADT complexes is carried out using the computer simulation technique. The results show that not only a correlation exists between the logarithm of the brain uptake and the electrostatic hydration free energy for the isomers of 99mTc-brain radiopharmaceu-ticals, but also a linear relationship exists between the logarithm of the ratio of the brain uptake of the syn isomer to that of the anti one and the difference between the electrostatic hydration free energy of the syn-isomer and that of the anti one. Furthermore, the investigation on the important factors influencing the brain uptakes of 99mTc-radiophar-maceuticals and the reasons of the different biodistribution of the isomers of the 99mTc-complexes is explored at the molecular level. The results may provide a reference for the rational drug design of brain imaging agents.

关键词： 99mTc-brain imaging agent isomer brain uptake electro-static hydration free energy.

SYNTHESIS OF NOVEL LIQUID CRYSTALLINE POLY(METH)ACRYLATES CONTAINING SILOXANE SPACER AND TERPHENYLENE MESOGENIC UNIT

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Chinese Journal of Polymer Science 2000年第2期18卷 101-107页

作者： Zhi-qian Zang Yu-fei Luo Dong Zhang Xin-hua Wan Qi-feng Zhou Department of Polymer Science & engineering, college of {2., peking university, beijing 100871, China 北京大学北京

Novel side-chain liquid-crystalline poly(meth)acrylates were synthesized using 1-(3-hydroxyl-propyl)-3-[(4 '-cyano-p-terphenyloxycarbonyl)alkyl]-1,1,3,3-tetramethyldisiloxane as the key intermediate. The polymers used a disiloxane moiety as decoupling spacer with cyano-p-terphenyl as mesogenic unit. The products were characterized by NMR, GPC, DSC and polarizing optical microscopy. All the polymers with cyano-p-terphenyl mesogens formed a stable mesophase. However, if the mesogenic unit is replaced by cyano-p-biphenyl, the liquid crystalline character will be lost. The results also showed that the decoupling is incomplete even if a complex and very flexible decoupling spacer is deliberately incorporated to obtain the highest possible decoupling effect.

关键词： liquid crystalline polymers polyacrylates 4 ''-cyano-p-terphenyl

IMPACT PROPERTIES OF METALLOCENE - CATALYZED ETHYLENE-α-OLEFIN COPOLYMERS

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Chinese Journal of Polymer Science 2002年第5期20卷 473-480页

作者： Xu-rong Xu Jun-ting Xu Lin-xian Feng Department of Polymer Science and engineering Zhejiang university Hangzhou 31002.,China Department of Polymer Science and engineering college of chemistry & molecular engineering peking university beijing 100871, China Department of Polymer Science and engineering Zhejiang University Hangzhou 310027

The impact properties of two selected metallocene-catalyzed ethylene-butene copolymers and one conventionalcopolymer were evaluated using Izod impact test. It is found that the metallocene-catalyzed copolymer shows superior impactproperties. This result was explained on the basis of the more homogeneous inter-molecular composition distribution andnarrower molecular weight distribution, which leads to more homogeneous morphology with fewer defects. Stepwisecrystallization improves the impact properties, especially in the crack propagation process, to a large extent. This is due to thedecrease of entanglements by stepwise crystallization, which is advantageous for the chain slip and shear. The polymer withheterogeneous intra-molecular composition distribution exhibits a more evident improvement of impact properties understepwise crystallization.

关键词： Metallocene-catalyzed ethylene-butene copolymer Impact properties molecular heterogeneities Thermal treatment

SYNTHESIS OF HYBRID MESOPOROUS POLYSTYRENE-SILICA MATERIALS WITH NON-SURFACTANT CITRIC ACID AS TEMPLATE VIA SOL-GEL PROCESS

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Chinese Journal of Polymer Science 2002年第6期20卷 565-572页

作者： Jie Bai Jin-yu Zheng Kun-yuan Qiu Yen Wei Department of Polymer Science & engineering college of {2. & molecular engineering, peking university beijing 100871, China Department of {2., Drexel university, Philadelphia, PA 19104, USA Department of Polymer Science & engineering College of Chemistry & Molecular Engineering Peking University 北京 100871 Department of chemistry Drexel University Philadelphia PA 19104 美国

Hybrid mesoporous polystyrene-silica materials were successfully prepared through HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and triethoxysilyl-functionalized polystyrene obtained via atom transfer radical polymerization (ATRP) of styrene, in the presence of citric acid (CA) as non-surfactant template or pore-forming agent and followed by ethanol extraction to remove template molecules. The materials were characterized by infrared spectroscopy OR), N-2.adsorption-desorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The results indicate that the materials prepared with 50 wt%-60 wt% template contents have average pore sizes of 2.3 nm and large surface areas (ca. 886 m(2./g) as well as high pore volumes (ca. 0.53 cm(3)/g). The mesoporosity arises from interconnected channels and pores with disordered arrangements. The pore diameters and pore volumes increase as the template content is increased. The pore diameters show a little change upon heating at 2.0degreesC overnight. However, the materials do not have good hydrothermal stability.

关键词： atom transfer radical polymerization hybrid material mesoporous polystyrene silica

CONTROLLED RELEASE FROM PDMAEMA GELS PREPARED BY GAMMA RADIATION

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Chinese Journal of Polymer Science 2002年第5期20卷 409-412页

作者： Ning Liu Min Yi Shuang-ji Chen Hong-fei Ha college of chemistry and {2. engineering peking university beijing 100871, China Department of Biochemistry college of Applied Arts and Science, beijing Union university beijing 100083. China college of chemistry and {2. engineering Peking University 北京 100871 Department of Biochemistry College of Applied Arts and Science Beijing Union University 北京 100083

Poly(N,N-dimethylaminoethyl methacrylate) (polyDMAEMA) hydrogels prepared by gamma-irradiation showed obvious temperature-sensitivity in a temperature range of 38-40degreesC and pH-sensitivity at pH=2.5. They also showed electric response behavior although it was not typical. The hydrogels were used in controlled release at different pH, temperature, and electric voltage. The release rates of methylene blue (MB) from the gels at 52.egreesC and pH=1.2. were faster than those at 2.degreesC and pH=10.56, respectively. In addition, the release rate at a field voltage of 5.0 was also faster than that without electric field.

关键词： poly(N,N-dimethylaminoethyl methacrylate) environmental sensitivity hydrogel controlled release

Crystal Structure of Triethyl 6-benzoyl-3a-(4-fluorophenyl)-2.3,3a,4,5,6-hexahydro-5-methyl-1H-pyro〔1,2.a〕〔1,5〕benzodiazepine-1,2.3-tricarboxylate

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Chinese Journal of Structural chemistry 1999年第4期 18-22页

作者： WANG HongZhong\ XU JiaXi\ MI BaoYu\ JIN Sheng* (college of chemistry and {2. engineering, peking university, beijing 100871)

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关键词： crystal structure pyrro1 2.1 5benzodiazepine 1

Luminescence resonance energy transfer based on β-NaYF_4:Yb,Er nanoparticles and TRITC dye

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Science China chemistry 2009年第10期52卷 1590-1595页

作者： SUN LingDong, GU JianQin, ZHANG ShuZhuo, ZHANG YaWen & YAN ChunHua beijing National Laboratory for molecular Sciences, State Key Lab of Rare Earth Materials {2. and Applications & PKU-HKU Joint Lab in Rare Earth Materials and Bioinorganic {2., college of {2. and molecular engineering, peking university, beijing 100871, China beijing National Laboratory for molecular Sciences State Key Lab of Rare Earth Materials Chemistry and Applications & PKU-HKU Joint Lab in Rare Earth Materials and Bioinorganic Chemistry College of Chemistry and Molecular Engineering Peking University Beijing China

β-NaYF4:Yb,Er nanoparticles (NPs) are one of the most efficient upconversion materials, which can convert near-infrared light to higher-energy light through multiple photon absorptions or energy transfer. In addition, they may be attractive alternative donors for luminescence resonance energy transfer (LRET) studies, because of their sharp absorption and emission profiles, high quantum yields, large anti-stokes shifts, long lifetime, low toxicity, and superior photo-stability. In principle, many problems of fluorescence resonance energy transfer (FRET), such as excitation of acceptors, emission overlaps between donors and acceptors, high background noise, potential toxicity, and instability, can be overcome using β-NaYF4:Yb,Er NPs as energy donors. Because the organic coating induced separation can significantly reduce the energy transfer efficiency and aqueous FRET system is difficult to be applied in devices, we demonstrate a novel NP-dye LRET system in solid state. The emission of the β-NaYF4:Yb,Er NPs at 539 nm overlaps with the absorption of the tetrametrylrhodarnine isothiocyante (TRITC), satisfying the requirement of LRET process. Since TRITC molecules are adsorbed on the β-NaYF4:Yb,Er NPs by an electrostatic interaction, the interaction distance is suitable for LRET without any further modulation. The resultant solid LRET system is ready for the further applications for devices.

关键词： upconversion emission β-NaYF4:Yb Er nanoparticles TRITC assembly luminescence resonance energy transfer (LRET)

Changes of decay rates of radioactive ^(111)In and ^(32.P induced by mechanic motion

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Science China chemistry 2007年第2期50卷 170-174页

作者： HE YuJian1,QI Fei2.& QI ShengChu3 1 college of chemistry and Chemical {2.,Graduate university of Chinese Academy of Sciences,beijing 100049,China 2.No. 1,Gravenhurst Court,Gaithersburg,Md 2.878,USA 3 Department of Applied chemistry,peking university,beijing 100871,China college of chemistry and Chemical {2. Graduate University of Chinese Academy of Sciences Beijing China No. 1 Gravenhurst Court Gaithersburg USA Department of Applied chemistry Peking University Beijing China

The changes of decay rates of radionuclide 111In(electron capture) and 32.(β decay) induced by exter-nal mechanic motion are studied. The results indicate that,in the external circular rotation in clockwise and anticlockwise centrifuge on Northern Hemisphere(radius 8 cm,2.00 r/min) ,the half life of 111In compared with the referred(2.83 d) is decreased at 2.83% and increased at 1.77%,respectively;the half life of 32. compared with the referred(14.2. d) is decreased at 3.78% and increased at 1.75%,respec-tively. When the clockwise and anticlockwise rotations increase to 4000 r/min,the half life of 111In is decreased at 11.31% and increased at 6.36%,respectively;the half life of 32. is decreased at 10.08% and increased at 4.34%,respectively. When the circular rotation is removed,the decay rates of 111In and 32. return back to the referred,respectively. It is found that the external circular rotations in clockwise and anticlockwise centrifuge selectively increased and decreased the decay rates of 111In and 32.,respec-tively,and the effects are strongly dependent on the strength of circular rotation. It is suggested that these effects may be caused by the chiral interaction.

关键词： circular rotation helical motion 111In 32. decay rate chirality

TARTARIC ACID TEMPLATED SYNTHESIS OF MESOPOROUS Ti-INCORPORATED SILICA AND ITS CATALYTIC ACTIVITY FOR THE RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE

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Chinese Journal of Polymer Science 2002年第4期20卷 361-368页

作者： Jie-bin Pang Chang-ming Dong Kun-yuan Qiu Yen Wei Department of Polymer Science and engineering college of {2. and molecular engineering peking university beijing 100871, China Department of {2. Drexel university Philadelphia, Pennsylvania 19104, USA Department of Polymer Science and engineering College of Chemistry and Molecular Engineering Peking University 北京 100871 Department of chemistry Drexel University 美国 Pennsylvania

Ti-incorporated mesoporous silica materials with pore diameters of 3-4 nm have been prepared via the co-hydrolysis and co-condensation reactions, that is the sol-gel reactions, of titanium (IV) tetrabutoxide and tetraethylorthosilicate in the presence of tartaric acid as template, followed by extraction with ethanol to remove the templatemolecules. The materials were characterized in detail by Fourier transform infrared spectroscopy, nitrogen adsorption-desorption test, powder X-ray diffraction, transmission electron microscopy and X-ray energy dispersive spectroscopy. Theresults indicate that the Ti-containing silica materials have large specific surface areas (ca. 12.0 m^2.g^(-1)) and pore volumes(ca. 0.900 cm^3 g^(-1)). The mesoporosity arises from disordered interconnecting channels or pores. The Ti-incorporated silicasexhibit catalytic activity for the ring-opening polymerization of ε-caprolactone, otherwise, the pure mesoporous silicamaterial shows no catalytic activity under the identical conditions.

关键词： Mesoporous material Ti-incorporated silica ε-Caprolactone Ring-opening polymerization Sol-gel reactions