PROPELLANTS EXPLOSIVES PYROTECHNICS
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2022
·Vol. 48
·期 2
·e202200199
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IF 2.134
Pengfei Su,Xiu-tian-feng E,Jingna Wang,Yanlong Zhu,Gao Zhang,Hai Chang,Ke Liu,Zihui Meng
Organoaluminum compounds have been employed as catalysts in many reactions. However, due to their high reactivity of the Al−C bond towards water or air, the accurate analysis and detection of organoaluminum compounds are still challenging. Here we demonstrate the possibility of rapidly and precisely detecting the purity and impurities of triethylaluminium (TEAL). An indirect GC-MS method via alcoholysis reaction using a designed alcoholysis reactor was adopted to detect and separate the main components and impurities of the synthesized TEAL. Previously, the nuclear magnetic resonance (NMR) and the inductively coupled plasma-mass spectrometer (ICP-MS) methods were also selected to detect the main compounds in the synthesized TEAL. The impurities in TEAL was identified as n-butyl aluminum, and the purity of synthesized TEAL is 97.47 % with high accuracy (ca. 99 %). This work suggests a new strategy to detect the purity and impurities of some kind of hazardous compounds.
研究领域:
分析化学
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催化化学
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高影响因子
IRANIAN POLYMER JOURNAL
·
2018
·Vol. 27
·期 8
·537-544
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IF 1.278
Li Peipei,Liu Kai,Zhang Binbin,Liu Jinhui,Hua Jing
Coordination polymerization of butadiene was initiated by a catalyst system consisting of tributyl phosphate (TBP) as ligand, molybdenum pentachloride as primary catalyst and triethyl aluminum substituted by m -cresol as co-catalyst. The effects of the substitution of m -cresol on the activity of the catalyst system, molecular weight and molecular weight distribution, intrinsic viscosity and microstructures of the resulting polymers were investigated in details. The molecular weight and molecular weight distribution of the polymerization products were determined by GPC. The microstructure of the polymerization products was characterized by FTIR, 13 C NMR and DSC techniques. The experimental results indicated that the polymerization activity of the reaction system and the molecular weight of the polymerization products gradually increased with the increase of the substitution content of m -cresol, namely, Al(OPhCH 3 ) 2 Et > Al(OPhCH 3 )Et 2 > Al(OPhCH 3 ) 0.5 Et 2.5 >AlEt 3 . The 1,2-structure contents of the polymerization products could be adjusted between 89 and 91% through the control of the substitution of m -cresol, and there was minute quantities of crystalline structures in the resulting polymers due to the increasing content of the syndiotactic 1,2-polybutadiene. In a word, the existence and increase of steric hindrance of m -cresol made it easier for polymerization products to form interdisciplinary 1,2-structure.
研究领域:
高分子化学
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催化化学
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2024
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IF 13.3
Tao Guo,Wei Li,Chuanding Dong,Jingdai Wang,Yongrong Yang
The comonomer effect of ethylene/ α -olefin copolymerization in the Ziegler-Natta (Z-N) catalytic system, remaining largely elusive and less understood at the molecular level, has been of huge industrial importance and absorbing research interest for decades. Herein, four catalysts with similar physical structures but different polymerization activities and comonomer effects were synthesized by using n -butanol in combination with different secondary electron donors. By tracking catalyst formation, it was found that altering the secondary donor changes the ν (O-H) stability and in turn the MgCl 2 facet growth, to influence the polymerization activity. In situ diffuse reflectance Ultraviolet–visible spectra show that different types of active Ti centers are in function in the ethylene polymerization and the ethylene/1-butene copolymerization. Tracing further the microscopic structures of active species upon triethylaluminium (TEA) activation by using Extended X-ray Absorption Fine Structure, it is found that: (i) for the catalysts with negative comonomer effect, the enhanced donor migration promotes the aggregation of active species and leads to the formation of TiCl 3 -like clusters; (ii) by contrast, for the catalysts with positive comonomer effect, the less mobile donors hinder the aggregation of active species, thus inducing the formation of isolated Ti 3+ sites. Our work reveals an evident correlation between the active center and the comonomer effect, which may be strongly modified by the aggregation of the former.
研究领域:
化学工程
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催化
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高分子科学
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DOI
高影响因子
POLYMER
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2024
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IF 4.1
Haoyun Deng,Zhixiong Yang,Mengzhen Zhou,Encai Ou,Yanbing Lu,Qiulan Zhou,Kun Liu,Weijian Xu
( Z )-1,3-pentadiene (Zp) exhibits a rigid planar molecular structure and is known for the typical 1,5-sigmatropic hydrogen shift, while it is commonly considered an inert monomer during polymerization. Herein, by utilizing the steric effect of the terminal methyl in Zp, the high trans -1,4-polypentadiene (HTPD) with highly ordered microstructure and well-defined sequence are successfully synthesized using barium dithymol/ tert- butyllithium/ tri -ethylaluminum trimetallic initiators based on anionic polymerization. The significant dependence of polymerization rate and trans -1,4-selectivity on ratio of Ba/Al/Li is demonstrated. The modification in microstructure ( trans -1,4 content ranging from 75 % to 92 %) and stereo-regularity (isotactic triad mm % > 65 %) are confirmed by nuclear magnetic resonance (NMR). Compared with the poly(( Z )-1,3-pentadiene) (PZp) prepared by n -BuLi containing σ -ligand modifiers, the strategy using a large steric initiator to achieve regular insertion of Zp into polymer chains is proved to be effective. Kinetics studies demonstrated that Ba–Al–Li system is characterized by retarded anionic polymerization (RAP), yet it shows a quasi-living process and enabling the preparation of stereometric block polymers such as polyisoprene- b -HTPD (PI- b -HTPD). Thermal performance analysis indicates that the obtained highly ordered polymers show superior thermoplastic properties ( T m = 77.4 °C) with crystallinity as an elastomer. Furthermore, reasonable interpretations for the structure formation, sequence, and rate reduction effected by the Ba/Al/Li trimetallic initiator are proposed.
研究领域:
高分子化学
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材料科学
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DOI
高影响因子
eScience
·
2026
·
IF 52.9
Donglei Zhao,Kaiwen Shi,Shuang Wu,Xinyi Liu,Haoxiang Sun,Jinze Hou,Diantao Li,Siyuan Shao,Xingwei Sun,Lihong Zhang,Youxuan Ni,Zhenhua Yan,Yong Lu,Jun Chen
The quasi-solid-state gel electrolytes (QSEs) fabricated through free-radical in situ polymerization show great promise for energy-dense solid-state lithium batteries, paving the way for next-generation electric vehicles and the low-altitude economy. However, the high-voltage-resistant QSEs were obtained under strict conditions within batteries, causing highly non-uniform electrolyte and poor compatibility with electrodes. Here we propose a universal C=C bond activation strategy by introducing activators with high maximum molecular surface electrostatic potential (ESP max ) to improve the condensed local softness of C=C bonds in a series of acrylate-based monomers. The activated C=C bonds result in decreased polymerization reaction energy barrier, and thus realize room-temperature free-radical polymerized QSE (RT-QSE). The RT-QSE effectively suppresses harmful interfacial reactions, maintains electrode structure stability and improves electrolyte uniformity, enabling high-areal-capacity cathodes. As a result, the 4 mAh cm −2 cathode remains 95.1% capacity after 100 cycles. Moreover, the 9.53 Ah pouch battery with an areal capacity cathode >10 mAh cm −2 shows a record high energy density of 656.6 Wh kg –1 . This work establishes a general design criterion for selecting activators and monomers to achieve uniform and compatible RT-QSEs for energy-dense solid-state lithium batteries.
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高影响因子
JOURNAL OF ORGANOMETALLIC CHEMISTRY
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2025
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IF 2.4
Zuoyuan Zhang,Ying Bi,Tianyu Lan,Liwu Zu,Shaobo Dong
Two novel dendritic nickel complexes were synthesized via Schiff base formation and complexation reactions using 1.0-generation dendritic polyamine (1.0 g), salicylaldehyde, and anhydrous nickel chloride. The structures of the dendritic ligands and their corresponding nickel complexes were characterized using FT-IR, ¹H NMR, ESI-MS, and elemental analysis.These dendritic nickel complexes were evaluated as catalyst precursors for ethylene oligomerization in the presence of co-catalysts, including EtAlCl₂, Et₂AlCl, AlEt₃, and IBAL. Among them, the combination of the new dendritic nickel complex (as the pre-catalyst) and Et₂AlCl (as the co-catalyst) exhibited notable catalytic performance. The effects of key reaction parameters—such as the Al/Ni molar ratio, temperature, and ethylene pressure—on oligomerization efficiency were systematically investigated.The catalytic activities of the two dendritic nickel complexes, featuring 5-bromosalicylaldehyde (5Br-cat) and 3,5-dibromosalicylaldehyde (3,5br-cat) in their branch chains, were determined to be 9.44 × 10⁵ g/(mol Ni·h) and 7.34 × 10⁵ g/(mol Ni·h), respectively. The results indicate that both catalytic activity and product distribution are strongly influenced by the nature of the co-catalyst and the structural features of the nickel complex. Notably, the catalytic activity of the dendritic nickel complex decreases with increasing steric hindrance in the branching structure.
研究领域:
化学
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材料科学
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DOI
高影响因子
CATALYSIS LETTERS
·
2025
·Vol. 155
·期 8
·1-13
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IF 2.4
Zhou Jing,Zhang Gongguo,Si Chongdian,Jin Manman,He Aihua,Niu Qingtao
Series of isoprene polymerizations with different polymerization time were performed by TiCl 4 /MgCl 2 type Ziegler-Natta catalysts. Polymerization kinetics showed catalytic activity had two-stage polymerization feature and the polymer chain microstructure gradually changed from the trans -1,4 and cis -1,4 mixed structure with low molecular weight ( M w ) as well as broad molecular weight distribution ( M w / M n ) at the early stage, to the final high trans -1,4 structure with high M w and narrow M w / M n . The high trans -1,4 units can enhance the tensile strength and hardness of the synthetic polyisoprenes, which are widely used for golf ball cover, medicinal material and shape memory material. Polymers were mainly isolated into Fraction C, D and G by the stepwise isothermal crystallization fractionation method. Fraction C and D had high trans -1,4 content, high trans -1,4-[II] dyad sequence concentration, high trans - trans unit linkage content and high crystallinity, which were generated by high trans -1,4 stereoselective active centers. While G fraction had low trans -1,4 content, low trans -1,4-[II] dyad sequence concentration, low trans - trans unit linkage content and low crystallinity, which were formed by the active center with low trans -1,4 stereoselectivity. The stereoselective transformation of active centers as well as trans -1,4 stereospecific polymerization mechanism of isoprene with TiCl 4 /MgCl 2 -AlEt 3 catalyst system was discussed. Graphical
研究领域:
高分子化学
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有机合成
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材料科学
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催化
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大分子化学
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物理化学
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DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
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2018
·Vol. 136
·期 1
·46906
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IF 1.901
Jinhui Liu,Jieting Geng,Kai Liu,Lingli Zou,Zhaobo Wang,Jing Hua
Molybdenum-based random 1,2-polybutadiene (1,2-PB) rubber, with its excellent wet skid resistance, low rolling resistance, and low heat buildup, can be used for green tread rubber, and it has significant benefits for the enhancement of the mechanical strength of 1,2-PB. In this study, we investigated in detail the effects of the electronegativity and steric hindrance of the cocatalyst on the stereoselectivity of the resulting polymers. In the case of cocatalysts with moderate electronegativities, the active centers were more stable; this resulted in a larger molecular weight and a higher conversion, whereas a cocatalyst with excessive electronegativity tended to initiate cationic polymerization. The high sterically hindered substituent restricted the coordination configuration of the monomer; this ultimately resulted in the increase in the 1,2 structure to 90%. Fourier transform infrared analysis showed that the content of trans -1,4 structure increased from 7 to 66%, and its crystallinity reached 59.2%, as calculated with differential scanning calorimetry when triethyl aluminum was used as the cocatalyst. Consequently, trans -1,4-polybutadiene crystals were introduced into the 1,2-PB elastomer in one step; this could be a promising facile route for strengthening 1,2-PB. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 46906.
研究领域:
高分子化学
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材料科学
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DOI
高影响因子
ADVANCES IN POLYMER TECHNOLOGY
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2016
·Vol. 37
·期 2
·629-636
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IF 1.114
Jun Wang,Na Zhang,Cuiqin Li,Weiguang Shi,Zhiyu Lin
A series of new hyperbranched salicylaldimine nickel complexes were synthesized by the Schiff's base and the complexation reactions with 1.0 generation hyperbranched macromolecules, salicyladehyde and nickel chloride hexahydrate as materials by employing two-step synthesis and one-pot synthesis, respectively. The hyperbranched salicylaldimine ligands and the complexes were characterized by FT-IR, 1 H NMR, UV, and ESI-MS. All nickel complexes, activated with Methylaluminoxane, exhibited high activities for ethylene oligomerization (TOF = 1.92–4.93 g/mol Ni h) and showed good selectivities for the longer chain oligomers produced (36.35–60.33%). When activated with ethylaluminum dichloride, it was found that a tandem process occurred in which ethylene oligomerization was followed by Friedel–Crafts alkylation of the reaction solvent, toluene. On increasing the pressure of ethylene and Al/Ni ratio, the catalytic activities of precatalyst increased and the processes became more selective for the shorter oligomers. Not only the polymerized parameters but also the length of alkyl chain of the ligands influenced the catalytic activities and selectivities for the longer chain oligomers. The catalytic activities and selectivities for the longer chain oligomers declined with the increase in length of alkyl chain of ligand.
研究领域:
有机化学
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催化化学
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高影响因子
Polymers
·
2019
·Vol. 11
·期 7
·1122
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IF 3.164
Mengmeng Zhao,Qaiser Mahmood,Chuyang Jing,Liang Wang,Guangqian Zhu,Xianhui Zhang,Qinggang Wang
A series of vanadium complexes bearing iminopyridine bidentate ligands with various electronic and steric properties:V1[CH2Ph],V2[CMe2CH2CMe3],V3[Ph] andV4[2,6-iPr2Ph] were prepared and characterized by IR spectroscopy and microanalytical analysis. The catalytic capacity of all the complexes has been investigated for isoprene polymerization and was controlled by tuning the ligand structure with differentN-alkyl andN-aryl groups. Activated by methylaluminoxane (MAO), the aryl-substituted complexV3[Ph] exhibited highcis-1,4 selectivity (75%), and the resultant polymers had high molecular weights (Mn= 6.6 × 104) and narrow molecular weight distributions (PDI = 2.3). This catalyst showed high activity up to 734.4 kg polymer (mol V)−1h−1with excellent thermostability even stable at 70 °C. Compared to the traditional VCl3/MAO catalytic system, iminopyridine-supported V(III) catalysts displayed higher catalytic activities and changed the selectivity of monomer enchainment fromtrans-1,4 tocis-1,4.Keywords:polyisoprene;iminopyridine ligands;vanadium complexes;VCl3/MAO;Ziegler-Natta polymerization
研究领域:
化学
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材料科学
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DOI
PubMed
高影响因子
Macromolecular Reaction Engineering
·
2023
·Vol. 17
·期 3
·2300013
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IF 1.5
Ying Zhang,Jian Ye,Yinzhi Jiang,Shuqin Jiang,Wei Xiao,Dongchu Wei
The bis(imino)pyridyl iron-based ethylene oligomerization catalysts have the advantages of mild reaction conditions, high activity and high selectivity to linear α -olefins. However, barriers, such as high polymer content in the product mixture and large methylaluminoxane (MAO) dosage, are still limitations for the development of these systems at the industrial scale. In this study, new cocatalysts are prepared by the reaction of alkylaluminums with urea and its derivatives, and successfully used to activate iron-based catalysts. It is found that the type and molar ratio of alkylaluminum and urea have significant influence on the performance of the cocatalysts. The activity of the preferred triisobutylaluminum/urea activated systems reaches more than 3.0 × 10 8 g (mol-Fe) −1 h −1 , and the polymer content can be controlled to be less than 2 wt.%. Notably, the catalytic system exhibits good high temperature stability, the activity can still reach 1.0 × 10 8 g (mol-Fe) −1 h −1 even at 120 °C. Further 1 H NMR studies show that alkylaluminum can react with the N H moieties of urea, forming complex alkylaluminum clusters, even aluminoxane-like structures. This study offers a promising family of cocatalysts, making it possible to simultaneously improve their performance and reduce their cost.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 79
·75023-75031
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IF 3.289
Qian Zhou,Ailian Wang,Huayi Li,Zhi Luo,Tao Zheng,Liaoyun Zhang,Youliang Hu
Five salicylates with different sizes of hydrocarbon substituents were firstly synthesized and employed as ecofriendly internal donors of the Ziegler–Natta catalyst for propylene polymerization. The influences of these salicylates and traditional, industrial, internal donor diisobutyl phthalates on the microstructure of polypropylene and active center in a Ziegler–Natta catalyst were studied. It was found that the catalyst activities of the catalysts containing salicylate internal donors with a proper volume were higher than the catalysts containing diisobutyl phthalate internal donors. GPC results showed that the molecular weights of polypropylene prepared by salicylate internal donors were lower than those prepared by diisobutyl phthalate, which indicated that the polypropylene chains produced by salicylate internal donors were easier to transfer than those prepared by diisobutyl phthalate internal donors. Deconvolution of the GPC curves exhibited that as the volume of the salicylate internal donor increased some of the active centers for low molecular weight transferred into the active centers for high molecular weight. The results of 13C-NMR and SSA both suggested that a salicylate internal donor with an appropriate catalyst size volume was beneficial for increasing the isotactic sequence length, isotacticity index and regular triads “mm” of polypropylene. However, further increasing the volume of the salicylate internal donor in a catalyst would lead to the polypropylene chain containing more stereo-defects. Moreover, the active centers with different stereospecificity parameters, piso, in the catalyst could explain the trend of stereo-defects in polypropylene chains when different internal donors were used. In addition, it was found that the isotactic sequence length and isotacticity index of polypropylene prepared by isobutyl 2-benzyloxy-3,5-isopropyl benzoate were close to that produced by a diisobutyl phthalate internal donor. Moreover, the lamella thickness distribution of the polypropylene produced by a salicylate internal donor was broad, which might have potential application for expanded polypropylene materials.
研究领域:
高分子化学
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材料科学
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催化
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DOI
高影响因子
危险品化学品经营许可证（带存储）