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Chinese Journal of polymer science 2002年第5期20卷 413-417页

作者： Ji-yuan Yang Jian Yu Mei Li Zhong-wei Gu xin-de feng department of polymer science and engineering peking university beijing 100871, china national research institute for family planning beijing 100081, china department of polymer science and engineering Peking University 北京 100871 national research institute for family planning 北京 100081

The copolymerization of DL-LA and 3-BMG was carried out in bulk with stannous 2-ethythexanoate as the catalyst. A series of copolymers with pendant protected groups were obtained and characterized by H-1-NMR and GPC analysis. The monomer reactivity ratios were evaluated by the Fineman-Ross method and the Kelen-Tudos method and found to be r(BMG)=1.96 and r(LA)=0.37, respectively.

关键词： 3-benzyloxymethyl 1,4-dioxane-2,5-dione DL-lactide reactivity ratios

SYNTHESIS OF NOVEL HYDROPHILIC BIOdeGRADABLE POLYESTER WITH FUNCTIONALIZED SIde CHAIN GROUPS

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Chinese Journal of polymer science 2001年第5期19卷 509-516页

作者： Ji-yuan Yang Jian Yu Huai-zhong Pan Zhong-wei Gu Wei-xiao Cao xin-de feng department of polymer science and engineering peking university beijing 100871, china national research institute for family planning beijing 100081, china dept. of Poly. Sci. and engineering Peking University Beijing 100871 China Natl. Res. Inst. for family planning Beijing 100081 China

A substituted glycolide, 3-benzyloxymethyl-1,4-dioxane-2,5-dione, was synthesized. It is a suitable precursor for the preparation of a new hydrophilic biodegradable poly(a-hydroxy acid). The polymerizations were carried out in bulk in the presence of Sn(Oct)(2) at 120-140 degreesC. The resulting polymers were subjected to hydrogenolysis with a Pd/C catalyst in a mixed solvent to remove the protecting benzyl groups. A novel poly(a-hydroxy acid) with pendant hydroxy groups was obtained. The hydrophilicity of the resulting polymer was evaluated preliminarily.

关键词： biodegradable polyester hydrophilicity functional pendant group

Measurement of Monomer Reactivity Ratios of D,L-3-Methylglycolide with Glycolide or D,L-Lactide

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Chinese Chemical Letters 2000年第9期11卷 815-818页

作者： Chang Ming DONG Kun Yuan QIU Zhong Wei GU xin de feng department of polymer science and engineering, College of Chemistry and Molecular engineering, peking university, beijing 100871 national research institute for family planning, beijing 100081 dept. of Poly. Sci. and engineering Coll. of Chem. and Molec. Eng. Peking University Beijing 100871 China Natl. Res. Inst. for family planning Beijing 100081 China

For monomer reactivity ratios study, the copolymerization of D,L-3-methylglycolide (MG) with glycolide (GA) or D,L-lactide (LA) was carried out in bulk to a certain low conversion in the presence of stannous octoate at 140 degrees C. The copolymer compositions were determined by H-1 NMR spectroscopy. The monomer reactivity ratios were evaluated by Fineman-Ross method, Kelen-Tudos method and linear least-squares method. The monomer reactivity ratios of D,L-3-methylglycolide and glycolide or D,L-lactide are r(mg)= 0.73, r(ga)= 1.47; r(mg)= 1.71, r(la)= 0.92, respectively.

关键词： D,L-3-methylglycolide glycolide D,L-lactide ring-opening copolymerization monomer reactivity ratios

SYNTHESIS AND PROPERTIES OF NEW MESOGEN-JACKETED LIQUID CRYSTALLINE polymerS

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Chinese Journal of polymer science 2000年第2期18卷 139-148页

作者： Qi-ding Mi Qi-feng Zhou department of polymer science & engineering, College of Chemistry peking university, beijing 100871, china 北京大学北京

Some new mesogen-jacketed liquid crystalline polymers (MJLCP) with polymer backbones, spacers, and mesogenic units of different structures were synthesized by radical polymerization. The mesomorphic behavior of these polymers was examined using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Their liquid crystallinity is influenced by the variation of polymer backbone, spacer, mesogenic unit and its terminal groups. The results show that 1) a more flexible polymer main-chain is more favorable to the formation of a liquid crystal phase, while 2) a flexible spacer will decrease the 'Jacket Effect' and the liquid crystallinity and 3) a subtle modification of the terminal groups on the mesogenic unit may also have a significant influence on properties of the polymers.

关键词： mesogen-jacketed liquid crystalline polymers polymer backbones spacers mesogenic units liquid crystallinity

SYNTHESIS AND CHARACTERIZATION OF A NOVEL BLUE LIGHT EMITTING ROD-COIL DIBLOCK OLIGOMER

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Chinese Journal of polymer science 2002年第5期20卷 401-407页

作者： Lifang Yang Haifeng He Hongqing Cao xinhua Wan Qi-feng Zhou department of polymer science & engineering College of Chemistry & Molecular engineering peking university beijing 100871, china department of polymer science & engineering College of Chemistry & Molecular Engineering Peking University 北京 100871 department of polymer science & engineering College of Chemistry & Molecular Engineering Peking University 北京 100871

Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl to quinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, M-w ca. 750) as flexible segments, were synthesized. The chemical structure and the number of repeating unit in PEO coil and PPP rod were characterized by H-1-NMR and MALDI-TOF mass spectrometry. The diblock oligomers showed good solubility in common organic solvents and aggregated in water as characterized by a blue shift in UV-vis absorption spectra, a red shift in emission spectra, quenching of the fluorescence and formation of the microfibrilla and fractal-like structures. The formation of different supramolecular structures meant that this effort might lead to commercial important highly organized functional materials.

关键词： rod-coil diblock oligomer MALDI-TOF mass spectrometry microfibrilla aggregate fractal-like pattern

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 Chemistry, peking university, beijing 100871, china 北京大学北京

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

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 310027,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 AND PROPERTIES OF A NEW AZOBENZENE SIde-CHAIN polymer CONTAINING A TEMPO RADICAL

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Chinese Journal of polymer science 2002年第4期20卷 285-290页

作者： Yong Zhang Ze-da Xu xing-he Fan Xiao-fang Chen xin-hua Wan Qi-feng Zhou department of polymer science and engineering College of Chemistry and Molecular engineering peking university, beijing 100871, china department of polymer science and engineering College of Chemistry and Molecular Engineering Peking University 北京 100871

To allow anisotropies of optical properties in a magnetic field, nitroxide radical is introduced into the ortho-position of the phenylene ring in the side chain. A new azobenzene side-chain polymer (TEMPO-PAZ) containing TEMPO radical was synthesized. The polymer has a good solubility in organic solvents. The ESR spectrum of the polymer indicated three absorption lines characteristic of TEMPO radical. The optical phase conjugated responses (I-4) of the polymer films were investigated by degenerate four-wave mixing (DFWM). The experimental results showed that optical phase conjugated response of the TEMPO-PAZ could be easily controlled by choosing the appropriate direction of magnetic field presumably due to the nitroxide radical in the TEMPO-PAZ molecular structure. For the polymer investigated here, the nitroxide radical was introduced to increase optical phase conjugated response intensity in a magnetic field, aiming originally at searching for a new photo-active organic magnetic multifunctional materials.

关键词： azobenzene nitroxide radical polymer photo-active organic magnetic materials optical phase conjugated responses

MECHANICAL PERTURBATION INDUCED MOLECULAR ALIGNMENTS IN A SIde-CHAIN LIQUID CRYSTALLINE POLYACETYLENE, POLY{10-[4-(4'-METHOXYPHENOXY-CARBOML)PHENOXYCARBONYL]-1-deCYNE}

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Chinese Journal of polymer science 1999年第3期17卷 289-294页

作者： Ben-zhong Tang Xiang-xing Kong xin-de feng department of Chemistry, Hong Kong university of science & Technology, Clear Water Bay, Kowloon, Hong Kong, china department of polymer science & engineering, College of Chemistry, peking university, beijing 100871, china department of Chemistry Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong department of polymer science and engineering College of Chemistry Peking University Beijing 100871 China

A new liquid crystalline polyacetylene containing a phenyl benzoate mesogen (5) is synthesized,whose mesomorphic properties are found to be easily 'tunab1e' by simple mechanical perturbation. Thepolymerization of 10- [ 4 - (4' -methoxyphenoxycarbonyl )phenoxycarbonyl] - 1 -decyne (4 ) in itiated by theWCl_6-Ph_4Sn/dioxane complex yields polymer 5 with a M_w of 28400. The molecular structure of 5 ischaracterized by NMR, IR, and UV spectroscopy and its liquid crystalline behavior is investigated by DSC,POM, and XRD analysis. Upon mechanical perturbation, 5 exhibits unusual agitation-induced high-strengthdisclinations, shear-induced inversion walls, and solidification-induced banded textures. Such phenomenahave been observed in the main-chain liquid crystalline polymers with rigid backbones, but have seldom beenreported for the side-chain liquid crystalline polymers with flexible backbones, suggesting that the rigidpolyacetylene backbone of 5 plays a constructive role in inducing the novel molecular alignments.

关键词： Liquid crystals Side-chain liquid crystalline polymers Polyacetylenes High-strength disclinations Inversion walls Banded textures Molecular alignments

SYNTHESIS OF DIACETYLENE-CONTAINING COPOLYESTERS AND THEIR DFFECT ON ELECTRO-OPTICAL PROPERTIES OF LIQUID CRYSTALS

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Chinese Journal of polymer science 1999年第2期17卷 193-196页

作者： Xiao-fang Chen Yao-wen Bai Yu-guo Ma Chen-hui Wang Dong Zhang xin-hua Wan Qi-feng Zhou department of polymer science and engineering, College of Chemistry, peking university, beijing 100871, china 北京大学化学院北京 100871 北京大学化学院北京

Some diacetylene-containing copolyesters with different ratios of dipropargyl 1,10-decanate anddipropargyl terephthalate were synthesized. Properties of these copolymers were characterized by differentialscanning calorimetry and polarizing optical microscopy. The copolymer could be cross-linked easily by UVirradiation in a liquid crystal matrix without adding any photoinitiator. The preliminary studies showed thatthe diacetylene-containing polymer network can assist liquid crystal molecules to align with the externalelectric field, thus reducing the response time of display devices.

关键词： Diacetylene-containing copolyesters polymer-stabilized liquid crystals Electo-optical of liquid crystals