期刊文献+
共找到20篇文章
< 1 >
每页显示 20 50 100
Polymerization Mechanism of α-Linear Olefin 被引量:3
1
作者 邢文国 张长桥 +2 位作者 于萍 刘成卜 魏云鹤 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第1期39-44,I0001,共7页
The density functional theory on the level of B3LYP/6-31G was empolyed to study the chain growth mechanism in polymerization process of α-linear olefin in TiCl3/AlEt2Cl catalytic system to synthesize drag reduction a... The density functional theory on the level of B3LYP/6-31G was empolyed to study the chain growth mechanism in polymerization process of α-linear olefin in TiCl3/AlEt2Cl catalytic system to synthesize drag reduction agent. Full parameter optimization without symmetry restrictions for reactants, products, the possible transition states, and intermediates was calculated. Vibration frequency was analyzed for all of stagnation points on the potential energy surface at the same theoretical level. The internal reaction coordinate was calculated from the transition states to reactants and products respectively. The results showed as flloes: (i) Coordination compounds were formed on the optimum configuration of TiCl3/AlEt2Cl.(ii) The transition states were formed. The energy di?erence between transition states and the coordination compounds was 40.687 kJ/mol. (iii) Double bond opened and Ti-C(4) bond fractured, and the polymerization was completed. The calculation results also showed that the chain growth mechanism did not essentially change with the increase of carbon atom number of α-linear olefin. From the relationship between polymerization activation energy and carbon atom number of the α-linear olefin, it can be seen that the α-linear olefin monomers with 6-10 carbon atoms had low activation energy and wide range. It was optimum to synthesize drag reduction agent by polymerization. 展开更多
关键词 Density functional theory Polymerization mechanism α-Linear olefin Drag reduction agent Ziegler-Natta catalyst
下载PDF
PDOL-Based Solid Electrolyte Toward Practical Application:Opportunities and Challenges
2
作者 Hua Yang Maoxiang Jing +3 位作者 Li Wang Hong Xu Xiaohong Yan Xiangming He 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第7期109-141,共33页
Polymer solid-state lithium batteries(SSLB)are regarded as a promising energy storage technology to meet growing demand due to their high energy density and safety.Ion conductivity,interface stability and battery asse... Polymer solid-state lithium batteries(SSLB)are regarded as a promising energy storage technology to meet growing demand due to their high energy density and safety.Ion conductivity,interface stability and battery assembly process are still the main challenges to hurdle the commercialization of SSLB.As the main component of SSLB,poly(1,3-dioxolane)(PDOL)-based solid polymer electrolytes polymerized in-situ are becoming a promising candidate solid elec-trolyte,for their high ion conductivity at room temperature,good battery elec-trochemical performances,and simple assembly process.This review analyzes opportunities and challenges of PDOL electrolytes toward practical application for polymer SSLB.The focuses include exploring the polymerization mechanism of DOL,the performance of PDOL composite electrolytes,and the application of PDOL.Furthermore,we provide a perspective on future research directions that need to be emphasized for commercialization of PDOL-based electrolytes in SSLB.The exploration of these schemes facilitates a comprehensive and profound understanding of PDOL-based polymer electrolyte and provides new research ideas to boost them toward practical application in solid-state batteries. 展开更多
关键词 Poly(1 3-dioxolane) Solid electrolyte Polymerization mechanism Composite electrolyte Practical application
下载PDF
Rheo-NMR: A versatile hyphenated technique for capturing molecular dynamics and structure under flow
3
作者 Yuqi Xiong Zishuo Wu +2 位作者 Lei Wu Chengyan Li Wei Chen 《Magnetic Resonance Letters》 2024年第1期50-60,共11页
The general development of Rheo-NMR during the last four decades as well as selective hyphenated apparatuses is presented.Based on different magnet types,the current review is divided into two categories,namely low-fi... The general development of Rheo-NMR during the last four decades as well as selective hyphenated apparatuses is presented.Based on different magnet types,the current review is divided into two categories,namely low-field and high-field NMR,while the timedomain NMR is normally applied in the former case and the frequency-domain NMR is adopted in the latter one.Depending on different rheometer cells,it can be further divided into tensile and shear mode Rheo-NMR.The combination of various rheometer cells and NMR facility guarantees our acquisition of molecular level structure and dynamics information under flow conditions,which is crucial for our understanding of the molecular origin of complex fluids.A personal perspective is also presented at last to highlight possible development in this direction. 展开更多
关键词 RHEO-NMR Polymer deformation mechanism Polymer rheology Viscoelastic property
下载PDF
Experimental Measurements of the Sensitivity of Fiber-optic Bragg Grating Sensors with a Soft Polymeric Coating under Mechanical Loading,Thermal and Magnetic under Cryogenic Conditions 被引量:2
4
作者 关明智 王省哲 +2 位作者 辛灿杰 周又和 马力祯 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第1期140-144,共5页
The strain and temperature sensing performance of fiber-optic Bragg gratings (FBGs) with soft polymeric coating, which can be used to sense internal strain in superconducting coils, are evaluated under variable cryo... The strain and temperature sensing performance of fiber-optic Bragg gratings (FBGs) with soft polymeric coating, which can be used to sense internal strain in superconducting coils, are evaluated under variable cryogenic field and magnetic field. The response to a temperature and strain change of coated-soft polymeric FBGs is tested by comparing with those of coated-metal FBGs. The results indicate that the coated-soft polymeric FBGs can freely detect temperature and thermal strain, their At variable magnetic field, the tested results indicate accuracy and repeatability are also discussed in detail. that the cross-coupling effects of FBGs with different matrixes are not negligible to measure electromagnetic strain during fast excitation. The present results are expected to be able to provide basis measurements on the strain of pulsed superconducting magnet/cable (cable- around-conduit conductors, cable-in-conduit conductors), independently or utilized together with other strain measurement methods. 展开更多
关键词 FBG net Experimental Measurements of the Sensitivity of Fiber-optic Bragg Grating Sensors with a Soft polymeric Coating under Mechanical Loading Thermal and Magnetic under Cryogenic Conditions
下载PDF
SIMULTANEOUS POLYMERIZATION AND FORMATION OF POLYPHENYLACETYLENE FILMS BY RARE-EARTH COORDINATION CATALYSIS Ⅳ.KINETICS AND MECHANISM OF POLYMERIZATION 被引量:1
5
作者 赵健 杨慕杰 +1 位作者 刘敏 沈之荃 《Journal of Rare Earths》 SCIE EI CAS CSCD 1990年第3期176-182,共7页
The CO_2 quenching method has been used for the first time to determine the active complex concen- tration in Nd(naph)_3-Al(i-Bu)_3 catalyst system for polymerization of phenylacetylene into polyphenylacetylene(PPA)fi... The CO_2 quenching method has been used for the first time to determine the active complex concen- tration in Nd(naph)_3-Al(i-Bu)_3 catalyst system for polymerization of phenylacetylene into polyphenylacetylene(PPA)films.The kinetics and mechanism of this polymerization have been investigated by CO_2 quenching and IR,UV analytical methods.The kinetic equation can be expressed as Rp=k[M][Cp],and the apparent activation energy is about 13.6 kJ/mol.There is self-termination of chain propagating.Models for formation of the active complex and polymerization mechanism are proposed. 展开更多
关键词 Nd AI SIMULTANEOUS POLYMERIZATION AND FORMATION OF POLYPHENYLACETYLENE FILMS BY RARE-EARTH COORDINATION CATALYSIS KINETICS AND mechanism OF POLYMERIZATION
下载PDF
STUDY ON POLYMERIZATION MECHANISM OF 3, 9,-DIALLYL-3, 9, -DIBENZYL-1, 5, 7, 11-TETRAOXASPIRO [5, 5] UNDECANE
6
作者 白如科 胡悦 +3 位作者 邹应芳 潘才元 Toshiyuki Uryu 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1992年第4期343-349,共7页
A new monomer, 3,9-diallyl-3, 9-dibenzyl-1, 5,7,11 - tetraoxa- spiro [5,5] undecane (6) was prepared by the reaction of 2- allyl- 2' - benzyl- propanediol - 1.3 with dibutyltin oxide, and then treated with CS_2. M... A new monomer, 3,9-diallyl-3, 9-dibenzyl-1, 5,7,11 - tetraoxa- spiro [5,5] undecane (6) was prepared by the reaction of 2- allyl- 2' - benzyl- propanediol - 1.3 with dibutyltin oxide, and then treated with CS_2. Monomer 4 could be initiated by cationic initiators to give a viscous polymer (white powder in the case of polymerization at 0℃). Upon the NMR and IR spectra of the obtained polymer, the components and their relative amount were estimated. The polymerization mechanism was discussed. 展开更多
关键词 Polymerization mechanism Cationic polymerization Spirocarbonates 3 9-diallyl-3 9-dibenzyl-1 5 7 11-tetraoxaspiro (5 5) undecane
下载PDF
STUDIES ON POLYMERIZATION MECHANISM OF CONJUGATED DIENE WITH η~3-ALLYL RARE EARTH MODEL COMPLEX
7
作者 Feng Fu LI Ying Tai JIN Feng Kui PEI Fo Song WANG Changchun Institute of Applied Chemistry,Academia Sinica.Changchun,130022Wen Ling Wu Department of Chemistry,Fudan University,Shanghai 200433 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第3期281-282,共2页
(η^-C_H_5)_2CeCl_5Mg_2(tmed)_2 was used as a catalyst to polymerize isoprene,Terminal ends of polyisoprene were identified as -CH_2-CH=CH_,which indicates that the insertion reaction of the monomer occurred between ... (η^-C_H_5)_2CeCl_5Mg_2(tmed)_2 was used as a catalyst to polymerize isoprene,Terminal ends of polyisoprene were identified as -CH_2-CH=CH_,which indicates that the insertion reaction of the monomer occurred between η^-allyl and cerium ion and gives a direct evidence for the η^-allyl mechanism of conjugated diene polymerzation with rare earth coordination catalysts. 展开更多
关键词 POLY ALLYL RARE EARTH MODEL COMPLEX STUDIES ON POLYMERIZATION mechanism OF CONJUGATED DIENE WITH
下载PDF
DSC STUDY ON THE WATER-ABSORBING MECHANISM OF PLASMA POLYMERIZED N-VINYL-2-PYROROLIDONE
8
作者 Ding Sheng YU R.E.MARCHANT 《Chinese Chemical Letters》 SCIE CAS CSCD 1991年第11期889-892,共4页
Water existing in water-absorbing plasma polymerized N-vinyl-2-pyrrolidone(PPNVP) include pure bulk water, freezable water and non-freezing, or bound, water. The C-N bond of N, N-disubstituted amides in PPNVP was cons... Water existing in water-absorbing plasma polymerized N-vinyl-2-pyrrolidone(PPNVP) include pure bulk water, freezable water and non-freezing, or bound, water. The C-N bond of N, N-disubstituted amides in PPNVP was considered as an active binding site for bound water. 展开更多
关键词 DSC STUDY ON THE WATER-ABSORBING mechanism OF PLASMA POLYMERIZED N-VINYL-2-PYROROLIDONE 加加 ESCA NVP
下载PDF
STUDIES ON THE KINETICS AND INITIATION MECHANISM OF ACRYLAMIDE POLYMERIZATION USING CERIC/ACETOACETANILIDE SYSTEM AS INITIATOR
9
《Chinese Chemical Letters》 SCIE CAS CSCD 1992年第2期103-106,共4页
It is found that acetoacetanilide possesses very high promoting reactivity towards ceric ion in initiating polymerization of vinyl monomer. The kinetics of acrylamide polymerization and the activation energies were st... It is found that acetoacetanilide possesses very high promoting reactivity towards ceric ion in initiating polymerization of vinyl monomer. The kinetics of acrylamide polymerization and the activation energies were studied. The initiation mechanism of ceric/acetoacetanilide is proposed on the basis of experimental results of FT-IR and ESR. 展开更多
关键词 AAA IV AS ESR STUDIES ON THE KINETICS AND INITIATION mechanism OF ACRYLAMIDE POLYMERIZATION USING CERIC/ACETOACETANILIDE SYSTEM AS INITIATOR
下载PDF
Novel Shape-Memory Polymer with Two Transition Temperature Based on Two Different Memory Mechanism
10
作者 Liu Guoqin Ding Xiaobing Cao Yiping Zheng Zhaohui Peng Yuxing 《合成化学》 CAS CSCD 2004年第z1期92-92,共1页
关键词 PMMA Tg Tm IPN Novel Shape-Memory Polymer with Two Transition Temperature Based on Two Different Memory mechanism
下载PDF
Effect of CF and RPP on the Mechanical and Electrical Properties of Smart Aggregate 被引量:1
11
作者 王海峰 MEI Zhen 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第2期437-444,共8页
By using redispersible polymer powder(RPP) and carbon fiber(CF) to adjust the flexibility and electrical properties of the smart aggregate, a new kind of smart aggregate with Z type structure was proposed. The stu... By using redispersible polymer powder(RPP) and carbon fiber(CF) to adjust the flexibility and electrical properties of the smart aggregate, a new kind of smart aggregate with Z type structure was proposed. The study shows that Z type aggregate is more sensitive to the feedback of external force than the prism aggregate in the same loading environment, and it indicates that Z type aggregate is more suitable for the research and application of concrete health monitoring. Although the incorporation of RPP would cause the compressive strength of the aggregates and the elastic modulus of hardened cement mortar to reduce slightly within the dosage of RPP by 2.25% because of the polymer film formed in the internal system, this would improve the deformability of the aggregates. In the early loading stage(in the first 60 seconds), the intelligent concrete specimens implanted with Z type smart aggregate do not show higher sensitivity as expected, although the resistance change rate changes a little bit more, the overall of it is still in balance. Adding RPP could improve the flexibility of smart aggregates exactly, and it plays an active role in prolonging the life of the smart aggregates. By implanting Z type aggregates the damage and failure of the concrete structure could be predicted accurately in this study. The results of this paper will help to promote further research and application of intelligent concrete. 展开更多
关键词 carbon fiber(CF) redispersible polymer powder(RPP) mechanical and electrical properties smart aggregate intelligent concrete
下载PDF
Thermal Polymerization of Cyanate Ester-Benzoxazine:Study of a Functional Model Compound
12
作者 WANG Fan ZHOU Hui +3 位作者 WAN Li DONG Bin LI Shengchao QI Huimin 《上海航天(中英文)》 CSCD 2022年第1期122-128,161,共8页
A novel benzoxazine(BOZ)monomer is synthesized by a pot method with solvent-free to blend with cyanate ester(CE).A soluble intermediate is obtained after being cured for 20 h at 80℃.The two model compound and the ble... A novel benzoxazine(BOZ)monomer is synthesized by a pot method with solvent-free to blend with cyanate ester(CE).A soluble intermediate is obtained after being cured for 20 h at 80℃.The two model compound and the blends are analyzed with the infrared radiation(IR),nuclear magnetic resonance(NMR)spectroscopy,and differential scanning calorimetry(DSC).The results show that an intermediate of the iminocarbonate and BOZ structures is formed by the ring-open BOZ reacting with the cyanate groups and ring-unopened BOZ.Moreover,rearrangement and ring-opening occur in the postcure of the intermediate to form the alkyl isocyanurate structure with polybenzoxazine. 展开更多
关键词 thermosetting resin benzoxazine(BOZ) cyanate ester(CE)resin polymerization mechanism
下载PDF
Influences of SiO2/Na2O Molar Ratio on Aging and Chemical Modification of Water Glass
13
作者 Huan Yang Hailan Xu +4 位作者 J. Kriss Frank Guangtong Xu Weiwei Huan Chaoying Ni Yuxiang Yang 《Open Journal of Inorganic Chemistry》 2016年第2期125-134,共10页
In this paper, the content of water glass before and after adding modifying agent was measured by Trimethylsilyl-gas-chromatography. The experimental results showed that different modulus of water glass could generate... In this paper, the content of water glass before and after adding modifying agent was measured by Trimethylsilyl-gas-chromatography. The experimental results showed that different modulus of water glass could generate different content of mono-silicate acid and oligomeric silicate acid in water glass. After a period of storage, different modulus of water glass led to decrease of silicate content at different levels. Because higher content of Na<sub>2</sub>O in water glass tended to incur the alkaline polymerization, the occurrence of depolymerization of silicate species would lead to an increase of oligomeric silicate species, resulting in a drawback of silicate species content after a period of storage. And contrary to that, lower content of Na<sub>2</sub>O in water glass tended to incur the acidic polymerization. When the modifying agent was added to the newly made water glass, the amount of mono-silicate acid and oligomeric silicate acid also decreased. In modified water glass, the change of each silicate acid species was less than that in unmodified water glass. These results showed that the modifying agent retarded the aging of water glass. It had remarkable significance on the theory and practical application of water glass chemistry. 展开更多
关键词 Water Glass MODULUS Polymerization mechanism Chemical Modification TMS-GC Method
下载PDF
Effect of Reactive Nanoclays on Performances of PMMA/Reactive Nanoclay Nanocomposites
14
作者 陈世伟 卢旭晨 +2 位作者 WANG Tizhuang PAN Feng ZHANG Zhimin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第6期1193-1200,共8页
PMMA/reactive nanoclay nanocomposites were prepared by emulsion polymerization using two different reactive nanoclays. X-ray diffraction(XRD) and thermogravimetric analysis(TGA) results confirmed that the reactive... PMMA/reactive nanoclay nanocomposites were prepared by emulsion polymerization using two different reactive nanoclays. X-ray diffraction(XRD) and thermogravimetric analysis(TGA) results confirmed that the reactive nanoclays, kaolinite and montmorillonite, were obtained by the silylation reaction and the double bonds were grafted onto the edges and surfaces of the nanoclays. The presence of reactive nanoclays could increase the average molecular weights, the glass transition temperatures(Tg) and improve the thermal properties of nanocomposite. The tensile properties, Young's modulus, and the aging properties of the nanocomposite films were also enhanced while the light transmittance decreased. Furthermore, the nanocomposites with the reactive kaolinite presented better performances than that with the reactive montmorillonite. Finally, the action mechanism of the reactive nanoclays to the performances of PMMA/reactive nanoclay nanocomposites was proposed. 展开更多
关键词 nanoclay emulsion polymerization nanocomposite thermal property mechanical property
下载PDF
Selective 3,4-Polymerization Mechanism of Isoprene Catalyzed by Rare Earth Alkyl Complexes
15
作者 LIU Ying SUN Cuihong +1 位作者 LI Xiaofang ZHANG Shaowen 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2014年第1期114-118,共5页
The mechanism of selective 3,4-polymerization reaction of isoprene catalyzed by the rare earth lutecium(Ⅲ) alkyl complexes [2,6-Me2Ph-N-CH2-C(CH2SiMe3)=N-PhMe2-2,6]Lu(CH2SiMe3)2(THF)was investigated by means ... The mechanism of selective 3,4-polymerization reaction of isoprene catalyzed by the rare earth lutecium(Ⅲ) alkyl complexes [2,6-Me2Ph-N-CH2-C(CH2SiMe3)=N-PhMe2-2,6]Lu(CH2SiMe3)2(THF)was investigated by means of the M06/sdd method with solvation effects taken into account.The results show that the structure of the catalyst core remained almost unchanged as the isoprene molecules were alternatively inserted into the complex at two opposite sides.The Gibbs free energies of the coordination complexes,transition state and intermediates indicate that all the isoprene molecules prefer to insert into the complex with the 3,4-polymerization selectivity as catalyzed by the catalyst,which is consistent with the experimental observations.It is found that the insertion reaction of each isoprene is exothermic,which comes mainly from the coordination of the isoprene molecule to the lutecium(Ⅲ) atom.The solvation effects were confirmed important in predicting the Gibbs free energies of the present reaction system. 展开更多
关键词 ISOPRENE Polymerization mechanism Density functional theory study Rare earth catalyst
原文传递
World’s first spaceflight on-orbit demonstration of a flexible solar array system based on shape memory polymer composites 被引量:10
16
作者 LAN Xin LIU LiWu +14 位作者 ZHANG FengHua LIU ZhengXian WANG LinLin LI QiFeng PENG Fan HAO SiDa DAI WenXu WAN Xue TANG Yong WANG Mian HAO YanYan YANG Yang YANG Cheng LIU YanJu LENG JinSong 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2020年第8期1436-1451,共16页
With a 10%reversible compressive strain in more than 10 deformation cycles,the shape memory polymer composites(SMPCs)could be used for deployable structure and releasing mechanism.In this paper,without traditional ele... With a 10%reversible compressive strain in more than 10 deformation cycles,the shape memory polymer composites(SMPCs)could be used for deployable structure and releasing mechanism.In this paper,without traditional electro-explosive devices or motors/controllers,the deployable SMPC flexible solar array system(SMPC-FSAS)is studied,developed,ground-based tested,and finally on-orbit validated.The epoxy-based SMPC is used for the rolling-out variable-stiffness beams as a structural frame as well as an actuator for the flexible blanket solar array.The releasing mechanism is primarily made of the cyanate-based SMPC,which has a high locking stiffness to withstand 50 g gravitational acceleration and a large unlocking displacement of 10 mm.The systematical mechanical and thermal qualification tests of the SMPC-FSAS flight hardware were performed,including sinusoidal sweeping vibration,shocking,acceleration,thermal equilibrium,thermal vacuum cycling,and thermal cycling test.The locking function of the SMPC releasing mechanisms was in normal when launching aboard the SJ20 Geostationary Satellite on 27 Dec.,2019.The SMPC-FSAS flight hardware successfully unlocked and deployed on 5 Jan.,2020 on geostationary orbit.The triggering signal of limit switches returned to ground at the 139 s upon heating,which indicated the successful unlocking function of SMPC releasing mechanisms.A pair of epoxy-based SMPC rolled variable-stiffness tubes,which clapped the flexible blanket solar array,slowly deployed and finally approached an approximate 100%shape recovery ratio within 60 s upon heating.The study and on-orbit successful validation of the SMPC-FSAS flight hardware could accelerate the related study and associated productions to be used for the next-generation releasing mechanisms as well as space deployable structures,such as new releasing mechanisms with low-shocking,testability and reusability,and ultra-large space deployable solar arrays. 展开更多
关键词 shape memory polymer composite releasing mechanism shape memory polymer composite tubes flexible solar array
原文传递
Preparation of a Crosslinked Chitosan Coated Calcium Sulfate Whisker and Its Reinforcement in Polyvinyl Chloride 被引量:15
17
作者 Jiayang Cui Yangben Cai +2 位作者 Wenjin Yuan Zhongfei Lv Shiai Xu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2016年第8期745-752,共8页
A calcium sulfate whisker (CSW) coated with glutaraldehyde crosslinked chitosan (GACS) was prepared to reinforce polyvinyl chloride (PVC) in this study. The results show that the optimum concentration of both ch... A calcium sulfate whisker (CSW) coated with glutaraldehyde crosslinked chitosan (GACS) was prepared to reinforce polyvinyl chloride (PVC) in this study. The results show that the optimum concentration of both chitosan (CS) and glutaraldehyde (GA) is 0.05 wt%. The tensile strength, impact strength, flexural modulus and vicat softening temperature of the PVC composite with 12 wt% of modified CSW are in- creased by 1 Z5%, 40.4%, 0.8% and 3.8% compared with those of the PVC composite with 12 wt~ of unmodified CSW, and by 2.9%, 42.4%, 2Z1% and 6.8% compared with those of pure PVC, respectively. The dynamic mechanical analysis results indicate that the modified CSW/PVC composite exhibits much higher storage modulus and glass transition temperature than those of unmodified CSW/PVC composite and pure PVC. In addition, the modified CSW/PVC composite also demonstrates good thermal properties with a high rapidest decomposition temperature (Trvd) and char residue. The scanning electron microscopy images of tensile-fractured surfaces show that the modified CSW has a strong interfacial adhesion with PVC matrix. 展开更多
关键词 Polyvinyl chloride Polymer composites Surface modification Calcium sulfate Mechanical properties
原文传递
Selective Insertion in Copolymerization of Ethylene and Styrene Catalyzed by Half-Titanocene System Bearing Ketimide Ligand: A Theoretical Study
18
作者 Xiaowei Xu Gaohong He +2 位作者 Ning-Ning Wei Ce Hao Yu Pan 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2017年第11期1731-1738,共8页
The copolymerization of ethylene and styrene can be efficiently carried out by using Cp*TiCl2(N=CtBu2)/ MAO (Cp*=η5-C5Me5) system, yielding the poly(ethylene-co-styrene)s with isolated styrene units. In order... The copolymerization of ethylene and styrene can be efficiently carried out by using Cp*TiCl2(N=CtBu2)/ MAO (Cp*=η5-C5Me5) system, yielding the poly(ethylene-co-styrene)s with isolated styrene units. In order to in- vestigate the reasons for formation of the structure, the mechanism of copolymerization, especially the selective in- sertion of ethylene and styrene, is studied in detail by density functional theory (DFT) method. At the initiation stage, insertion of ethylene is kinetically more favorable than insertion of styrene, and insertion of styrene kinet- ically and thermodynamically prefers 2,1-insertion. That is different from the conventional half-titanocene system, in which the 1,2-insertion is favorable. At chain propagation stage, the computational results suggest that the con- tinuous insertion of styrene is hard to occur at room temperature due to the high free energy barriers (28.90 and 35.04 kcal/mol for 1,2-insertion, and 29.15 and 34.00 kcal/mol for 2,1-insertion) and thermodynamically unfavora- ble factors in two different conditions. That is mainly attributed to the steric hindrance between the coming styrene and chain-end styrene or ketimide ligand. The computational results are in good agreement with the experimental data. 展开更多
关键词 polymerization mechanism density functional theory (DFT) half-tianocene COPOLYMERIZATION selec-tive insertion
原文传递
Study on polymerization and structure of polydiphenylamine
19
作者 JIN, Wen SONG, Fa-Yi DONG, Shao-JunLaboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China 《Chinese Journal of Chemistry》 SCIE CAS CSCD 1994年第2期138-147,共10页
The electrochemical oxidation of diphenylamine in acetonitrile produces an adherent uniform polymer film which exhibits mutiple colour variation(yellow-green-blue) in a wide range of potential scan. The polymerization... The electrochemical oxidation of diphenylamine in acetonitrile produces an adherent uniform polymer film which exhibits mutiple colour variation(yellow-green-blue) in a wide range of potential scan. The polymerization mechanism and the structure of the polymer were studied by cyclic voltammetry, FT-IR and in situ ESR. The results indicate that the electrochemical polymerization of diphenylamine belongs to a cationic radical polymerization process. During electrolysis, only oligomers were initialy produced, then polymer film was formed on the electrode surface. The electropolymerization performs via the 4,4' C-C phenyl-phenyl coupling mechanism. 展开更多
关键词 DPA electrochemical polymerization mechanism ESR.
原文传递
Solvent-Assisted Supramolecular Assembly of Cyclotetrasiloxane– Functionalized Alkynylplatinum(II) Terpyridine Complexes
20
作者 Ho-Leung Au-Yeung Sammual Yu-Lut Leung Vivian Wing-Wah Yam 《CCS Chemistry》 CAS 2019年第5期464-475,共12页
Our present study demonstrated and explored the solvent effects on the association mechanism of the supramolecular nanomaterials in a series of cyclo-tetrasiloxane-appended alkynylplatinum(II)terpyri-dine complexes.Th... Our present study demonstrated and explored the solvent effects on the association mechanism of the supramolecular nanomaterials in a series of cyclo-tetrasiloxane-appended alkynylplatinum(II)terpyri-dine complexes.Through the delicate balance of molecular interactions,some of these complexes were found to exhibit molecular association prop-erties,with possible morphological transformation in response to solvent polarities. 展开更多
关键词 SUPRAMOLECULAR cyclotetrasiloxane plati-num solvent effects hydrophobic interaction NANOMATERIAL metal-metal interactions noncova-lent interaction supramolecular polymerization mechanism
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部