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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 {2. of polymer science & engineering college of chemistry & molecular engineering Peking University beijing {12., China department of polymer {2. & engineering College of Chemistry & Molecular Engineering Peking University 北京 100871 department of polymer {2. & 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 supra{2. 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 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-{2. Zhou department of {2. science and engineering college of chemistry and molecular engineering Peking University, beijing 100871, China department of polymer {2. 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

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 {2. science and engineering Zhejiang University Hangzhou 31002.,China department of {2. science and engineering college of chemistry & molecular engineering Peking University beijing 100871, China department of polymer {2. 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 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 {2. of {2. 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 {2.s were found to have relatively low T-g and can form a smectic liquid crystal phase.

关键词： liquid crystal polymer polysiloxane

SMALL ANGLE LIGHT SCATTERING MEASUREMENT OF THE ISOTROPIC TO NEMATIC TRANSITION OF A SIde CHAIN NEMATIC POLYMETHACRYLATE

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Chinese Journal of polymer science 2002年第5期20卷 431-437页

作者： Zhong-ming Hu Ren-yuan Qian Shou-xi Chen Xiao-fang Chen Qi-feng Zhou Centre for molecular {2., institute of chemistry Chinese Academy of {2.s, beijing 100080, China department of polymer {2. & engineering {12. of chemistry & molecular engineering Peking University beijing 100871, China Centre for molecular science Institute of Chemistry Chinese Academy of Sciences 北京 100080 department of polymer {2. & engineering College of Chemistry & Molecular Engineering Peking University 北京 100871

The kinetics of I-->N transition of a side chain nematic polymethacrylate has been studied by small angle depolarized light scattering intensity measurements using a charge coupled device linear image sensor. The polymer shows the transition temperatures K52.79I in degreesC, The H-v scattering intensity T(q,t) during the transition I (at 80.2.0}greesC)-->N (at 75.8degreesC) shows that T(q) is independent of q for all t, and during the initial stage (in 6 s) T(t) increases exponentially with t. In the later stage of the transition T(t) approaches a saturation value in 2.min. This experimental result indicates that the I-->N transition of a liquid crystalline polymer is a spinodal type of phase transition mediated by orientation fluctuation.

关键词： side chain nematic polymer isotropic-nematic transition small angle depolarized light scattering

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 {2. of {2. 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

NITROXIde-MEDIATED FREE RADICAL SYNTHESIS OF MESOGEN-JACKETED LIQUID CRYSTAL polymerS

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Chinese Journal of polymer science 1999年第2期17卷 189-192页

作者： xin-hua Wan Hui-lin Tu Ying-feng Tu Dong Zhang Ling Sun Qi-feng Zhou Yu-ping Dong Mao Tang {2. of polymer science & engineering, college of chemistry, Peking University, beijing 100871, China {2. of Materials & Chemical engineering, beijing institute of Technology, beijing 100081, China 北京大学化学院北京 100871 北京大学化学院北京北京理工大学材料化学工程系北京 100081 北京理工大学材料化学工程系北京

The first TEMPO-mediated 'living' free radical polymerization of liquid crystalline monomer, 2. 5-bis[(4-methoxyphenyl)oxycarbonyl]styrene (MPCS), was carried out at 130 degrees C with BPO as an initiator. The {2. weight of the polymer can be varied from rather low values to high values while maintaining narrow polydispersity. It was observed that the polymerization of MPCS proceeded much faster than that of styrene. A tentative explanation for this fast polymerization was suggested.

关键词： TEMPO 'living' free radical polymerization mesogen-jacketed liquid crystal polymer mesophase polymerization

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-{2. feng department of {2., Hong Kong University of science & Technology, Clear Water Bay, Kowloon, Hong Kong, China department of polymer science & engineering, college of {2., Peking University, beijing 100871, China department of chemistry Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong department of polymer {2. 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 2.400. The {2. 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 {2. alignments.

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

FORMATION OF MESOPHASE MONO-DOMAINS AND MICRO-STRUCTURES IN THIN FILMS OF A SERIES OF COPOLYETHERS CONTAINING BOTH ODD-NUMBERED METHYLENE UNITS

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Chinese Journal of polymer science 2001年第4期19卷 391-397页

作者： feng-chao Xie Jie-ping Liu Dong-hang Yan Tian-bai He Ru-qing Zheng Er-qiang Chen State Key Laboratory of polymer Physics and {2., Changchun institute of Applied {2., Chinese Academy of sciences, Changchun 13002., China department of polymer science and engineering college of {2. Peking University beijing 100871, China 中科院长春应用化学所高分子物理与化学国家重点实验室吉林长春北京大学北京

The structural and morphological evolution of mono-domains in thin films has been investigated for a series of liquid crystalline (LC) copolyethers. The copolyethers studied were synthesized by the reaction of 1-(4-hydroxy-4 ' -biphenylyl)-2.(4-hydroxyl-phenyl)propane (TPP) with 1,7-dibromoheptane and 1,11-undecane at different compositions (coTPPs-7/11). In contrast to the solution-cast thin films without annealing, which exhibit the isotropic homogeneous molecular orientation, mono-domains with a homeotropic alignment were found in coTPP-7/11(5/5) after the thin films were annealed in the high-temperature columnar phase (Phi '). Similar to the nucleation process in {2. crystallization, transmission electron microscopic observations show that small mono-domains appear in the initial stage of annealing, where molecules form a uniaxial in-plane chain orientation. With increasing annealing time, the molecular orientation gradually became tilted with respect to the substrate surface, and finally, a uniaxial homeotropic molecular orientation was achieved after a prolonged annealing time. The lateral size of mono-domains was found to increase continuously with annealing time and grew into a circular shape, indicating an isotropic lateral growth scheme which implies a hexagonal molecular packing proved by the electron diffraction experiments.

关键词： main-chain liquid crystalline polymer structure morphology