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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-feng zhou centre for molecular science,{2., beijing 100080, china department of polymer science & engineering college of chemistry & molecular engineering 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 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 {12., beijing 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 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 {12. 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

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

AI for organic and polymer synthesis

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science china {2. 2024年第8期67卷 2461-2496页

作者： Xin Hong qi Yang Kuangbiao Liao Jianfeng Pei Mao Chen Fanyang Mo Hua Lu Wen-Bin Zhang Haisen {2. Jiaxiao Chen Lebin Su Shuo-qing Zhang Siyuan Liu Xu Huang Yi-{2. Sun Yuxiang Wang Zexi Zhang Zhunzhun Yu Sanzhong Luo Xue-feng Fu Shu-Li You Center of chemistry for Frontier Technologies Department of ChemistryZhejiang UniversityHangzhou 310027China Center of Basic molecular science Department of ChemistryTsinghua UniversityBeijing 100084China Guangzhou National Laboratory Guangzhou 510005China Center for Quantitative Biology Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijing 100871China State Key Laboratory of molecular engineering of {2.s Department of Macromolecular ScienceFudan UniversityShanghai 200433China School of Materials science and engineering Peking UniversityBeijing 100871China beijing National Laboratory for molecular {2. Center for Soft Matter Science and EngineeringKey Laboratory of Polymer Chemistry and Physics of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China AI for science(AI4S)-Preferred Program Shenzhen Graduate SchoolPeking UniversityShenzhen 518055China State Key Laboratory of Chemical Biology Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai 200032China department of Chemical sciences National Natural Science Foundation of ChinaBeijing 100085China State Key Laboratory of Organometallic chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

Recent years have witnessed the transformative impact from the integration of artificial intelligence with organic and polymer synthesis. This synergy offers innovative and intelligent solutions to a range of classic problems in synthetic chemistry. These exciting advancements include the prediction of {2. property, multi-step retrosynthetic pathway planning, elucidation of the structure-performance relationship of single-step transformation, establishment of the quantitative linkage between polymer structures and their functions, design and optimization of polymerization process, prediction of the structure and sequence of biological macromolecules, as well as automated and intelligent synthesis platforms. Chemists can now explore synthetic chemistry with unprecedented precision and efficiency, creating novel reactions, catalysts, and polymer materials under the datadriven paradigm. Despite these thrilling developments, the field of artificial intelligence(AI) synthetic chemistry is still in its infancy, facing challenges and limitations in terms of data openness, model interpretability, as well as software and hardware support. This review aims to provide an overview of the current progress, key challenges, and future development suggestions in the interdisciplinary field between AI and synthetic chemistry. It is hoped that this overview will offer readers a comprehensive understanding of this emerging field, inspiring and promoting further scientific research and development.

关键词： organic synthesis polymer synthesis machine learning prediction chemical database automated synthesis

A hydrogen-bonded organic framework containing fluorescent carbazole and responsive pyridyl units for sensing organic acids

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chinese Chemical Letters 2024年第9期35卷 458-463页

作者： Liangji Chen Zhen Yuan Fudong feng Xin zhou Zhile Xiong Wuji Wei Hao Zhang Banglin Chen Shengchang Xiang Zhangjing Zhang Fujian Key Laboratory of polymer Materials College of Chemistry and Materials ScienceFujian Normal UniversityFuzhou 350007China

Hydrogen-bonded organic frameworks(HOFs)are a promising candidate for optical sensing,but the lack of effective design strategies poses significant challenges to the construction of HOFs for organic acid *** this work,the first HOF for organic acid sensing is reported by constructing a multiplepyridine carbazole-based dense HOF,namely HOF-FJU-2.6,from a tripyridine-carbazole molecular 3,6-bis(pyridin-4-yl)-9-(4-(pyridin-4-yl)phenyl)-9H-carbazole(CPPY)with carbazole center for luminescence,pyridyl sites for its responsive of hydrogen proton,and narrow channels in the dense framework for the diffusion of hydrogen ***-FJU-2.6 exhibits differential responsively fluorescence sensing and recovery properties to formic,acetic,and propionic acids with different molecular sizes and p Kavalue(acid dissociation constant).The dissociation degree of various acids can be determined by analyzing the slope of changes in both peak wavelength and intensity of in-situ fluorescence,which easily enables the dual-corrective recognition of different *** varying degree of protonation at pyridine sites is proved to be the reason for differential sensing of various acids,as demonstrated by1H NMR spectra,X-ray photoelectron spectroscopy(XPS)characterization,and modeling studies.

关键词： Hydrogen-bonded organic framework Organic acid sensing Acids recognition Carbazole luminescence Pyridine protonation

The Crystallization Behavior of L-Poly(lactic acid)/Polypropylene Blends:The Acceleration for Both L-Poly(lactic acid)and Polypropylene

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chinese Journal of polymer {2. 2024年第6期42卷 775-786页

作者： Shuang-Cheng Li Wei-Jia zhou Wen-Jie Wu Jun Shao Shui-Liang Chen Hao-qing Hou Sheng Xiang college of chemistry&Chemical {2. and Nanofiber {2. Center of Jiangxi Province Jiangxi Normal UniversityNanchang330022China National engineering Research Center for Carbohydrate Synthesis/Key Lab of Fluorine and Silicon for Energy Materials and chemistry of Ministry of Education Jiangxi Normal UniversityNanchang330022China Wenzhou institute University of Chinese Academy of SciencesWenzhou325001China

For a polymer/polymer dismissible blend with two crystallizable components,the crystallization behavior of different components and the reciprocal influences between different crystals are interesting and important,but did not investigate in *** this study,the L-poly(lactic acid)/polypropylene(PLLA/PP)blends with different weight ratios were prepared by melt mixing and the crystallization behavior of the blends were *** showed that the crystalline structures of PLLA and PP were not altered by the *** the crystallization of PLLA,both the diffusion of chain segments and crystallization rate were enhanced under the existence of PP *** the crystallization of PP,its crystallization rate was depressed under the existence of amorphous PLLA {2. *** the PP crystallized from the existence of PLLA crystals,although the diffusion rate of PP was reduced by PLLA crystals,the nucleation positions were obviously enhanced,which accelerated the formation of PP *** investigation would supply more basic data for the application of PLLA/PP blend.

关键词： L-poly(lactic acid) Polypropylene Blends Crystalization behavior Crystallization acceleration

SYNTHESIS AND PROPERITIES OF SHISH-KEBAB-TYPE LIQUID CRYSTALLINE POLY(p-PHENYLENE)S

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chinese Journal of polymer {2. 2006年第3期24卷 265-271页

作者：郑世军 Kazuo Akagi Qun Xua Zi-fa Li Shao-kui Cao qi-feng {2. college of the Material science and {2. Zhengzhou University Zhengzhou 450052 China institute of Materials science University of Tsukuba Tsukuba 305-8573 Japan department of polymer {2. and engineering College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

Abstract The novel shish-kebab-type liquid crystalline poly（p-phenylene）s were synthesized through Suzuki coupling reaction from 2.5-bis[（4-n-alkoxyl）benzoyloxy]1,4-dibromobenzene （monomer 1） and 1,4-benzenediboronic acid bistrimethylene cyclic ester （monomer 2.. Their structure and properties were characterized by GPC, DSC, X-ray diffraction and polarizing optical microscope （POM）. It was found that the polymers turned to liquid crystalline phase above their melting point. The melting point （Tm） of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The mesophase was identified by X-ray diffraction method. The polymers could dissolve in common organic solvents and show strong blue fluorescence. The maximum absorption bands of polymers prepared from annealed films have large red-shift due to the spontaneous orientation of the liquid crystalline side chains. The same phenomena were also observed in the fluorescence spectra.

关键词： Conjugated polymer Liquid crystal Shish-kebab Fluorescence

Effect of spacer length on the liquid crystalline property of azobenzene-containing ABA-type triblock copolymers via ATRP

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chinese Chemical Letters 2007年第9期18卷 1129-1132页

作者： Xin De Tang Long Cheng Gao Xing He Fan qi feng {2. institute of New Materials Shandong Jiaotong UniversityJi’nan 250023China department of polymer {2. and engineering College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

The effect of flexible spacer length on the liquid crystalline property of ABA-type triblock copolymers containing azobenzene groups was investigated. For the study, the monomers, n-[4-(4-ethoxyphenylazo)phenoxy]alkyl methacrylates with varying methylene groups (n = 0, 2. 6) were used to synthesize a series of azobenzene-containing amphiphilic triblock copolymers PAnC–PEG–PAnC by atom transfer radical polymerization (ATRP). Differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and one-dimensional X-ray diffraction (1D WAXD) have shown that the glass transition temperatures of these copolymers decreased with increasing n, PA0C–PEG–PA0C has no mesophase, while both PA2.–PEG–PA2. and PA6C–PEG–PA6C have a nematic mesophase. These differences derive from the length of spacer groups between the polymer backbone and side-chain LC monomers.

关键词： Spacer group Liquid crystalline property Azobenzene Triblock copolymer Atom transfer radical polymerization (ATRP)