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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 {2. 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 {12. university beijing 100871, china peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China

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

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 {2. 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-{2. zhou centre for Molecular science, institute of chemistry chinese academy of sciences, beijing 100080, china department of polymer science & {12. college of chemistry & Molecular {12. peking university beijing 100871, china chinese Acad Sci Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China

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.egreesC)-->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 NOVEL LIQUID CRYSTALLINE POLY(METH)ACRYLATES CONTAINING SILOXANE SPACER AND TERPHENYLENE MESOGENIC UNIT

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chinese Journal of polymer {2. 2000年第2期18卷 101-107页

作者： Zhi-qian Zang Yu-fei Luo Dong Zhang Xin-hua Wan qi-{2. zhou department of polymer science & engineering, college of chemistry, peking university, {12. 100871, china peking Univ Coll Chem Dept Polymer Sci & Engn Beijing 100871 Peoples R China

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

A DSC STUDY OF PHOTOpolymerIZATION OF POLYESTERS CONTAINING CONJUGATED DIACETYLENES

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chinese Journal of polymer {2. 2000年第4期18卷 351-356页

作者： Yao-wen Bai Xiao-fang Chen Dong Zhang Xin-hua Wan qi-feng {2. department of polymer science and engineering, college of chemistry, peking university, beijing {12., china peking Univ Coll Chem Dept Polymer Sci & Engn Beijing 100871 Peoples R China

The photopolymerization of two kinds of prepolyesters containing conjugated diacetylene (PDA-6 and PDA-12. was investigated using DSC. By measuring the endothermic enthalpy of the prepolymers after different UV-irradiation times, the polymerizations were found to follow the first-order rate law which agreed with the results of other investigators using a different method. The endothermic enthalpy measurements of PDA-6 and PDA-12.before UV-irradiation precluded the possibility that the decrease of endothermic enthalpy was caused by thermal polymerization.

关键词： diacetylene-containing polyesters DSC enthalpy

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

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chinese Journal of polymer {2. 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 {2. department of polymer science & engineering, college of chemistry, peking university, beijing {12., 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

SYNTHESIS AND PROPERTIES OF A NEW AZOBENZENE SIDE-CHAIN polymer CONTAINING A TEMPO RADICAL

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chinese Journal of polymer {2. 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 {2. department of polymer science and engineering college of chemistry and Molecular engineering peking university, {12. 100871, china peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China

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

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

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chinese Journal of polymer {2. 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 {2. department of polymer science and engineering, college of chemistry, peking university, beijing {12., 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 {2. 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 department of polymer science & engineering, college of chemistry, peking university, {12. 100871, china department of Materials & Chemical engineering, {12. institute of Technology, {12. 100081, china peking Univ Coll Chem Dept Polymer Sci & Engn Beijing 100871 Peoples R China beijing Inst Technol Dept Chem & Mat Engn Beijing 100081 Peoples R China

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 molecular 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

Synthesis and ordered aggregation in water of a blue light-emitting PEO-PHP-PEO triblock oligomer

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chinese science Bulletin 2003年第15期48卷 1525-1530页

作者： HE Haifeng, CAO Hongqing, WAN Xinhua, TU Yingfeng, CHEN Xiaofang & zhou qifeng department of polymer science and engineering, college of chemistry and Molecular engineering, peking university, beijing 100871, china Correspondence should be addressed to Wan Xinhua (e-mail: xhwan@***) department of polymer {2. and engineering College of Chemistry and Molecular Engineering Peking University

A novel blue light-emitting coil-rod-coil triblock oligomer, PEO-PHP-PEO, which consists of para-hexaphenyl (PHP) as the rigid rod and poly(ethylene oxide) (PEO, M w = 750) as the flexible coil, has been synthesized. It is the first soluble poly(para-phenylene) molecule containing no lateral substituent, which can dissolve not only in organic solvents such as chloroform and THF, but also in water. The critical micelle concentration (CMC) of PEO-PHP-PEO in water is 5.2.×10-4 mol·L-1 and the surface tension at CMC, 鉉MC, is 61.2. mN·m-1. The absorption peak of the molecularly dissolved PEO-PHP-PEO in water is centered at 32. nm and the fluorescence spectrum has a maximum at 432.nm and shows the vibronic fine structure typical of molecular dissolution. The photoluminescence spectrum of the aggregate solution is similar to that of the PHP polycrystal film, indicating that the ordered packing of PHP block has taken place due to a combination of hydrophobic interaction and p-p stacking. The oligomer self-assembles into cotton-like nanofibers with diameter of about 2. nm in 5.0×10-3 mol·L-1 aqueous solution.

关键词：合成工艺低聚物聚乙烯荧光光谱 PHP 对六苯基