检索结果-南通市图书馆

Macrocyclic Binuclearα-Diimine Nickel Catalysts for Ethylene Polymerization

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2023年第5期39卷 797-802页

作者： YANG Jingshuang ZHANG Yuxing jian zhongbao State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022P.R.China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026P.R.China

Polyolefins are globally important *** weight and molecular weight distribution are two key parameters for determining the properties of polyolefin *** this contribution,we develop a strategy for combining the macrocyclic framework and the binuclear effect into the benchmarkα-diimine late transition metal catalysts,and thus macrocyclic binuclearα-diimine nickel catalysts(Ni_(2)-Me and Ni_(2)-iPr)are *** to the classical Brookhart's acyclic mononuclearα-diimine nickel analogues(Ni_(1)-Me and Ni_(1)-iPr),these nickel catalysts exhibit enhanced thermostability(up to 110℃)and produce polyethylenes with higher molecular weights(up to 7 times)and lower branching densities(as low as 9 branches/1000C)in methylaluminoxane(MAO)activated ethylene *** translates into the ability of the catalyst to afford more linear high molecular weight *** particular,bimodal polyethylenes with broad molecular weight distributions(Mw/Mn=8.08-14.66)are generated by the sole *** work affords diverse polyethylenes.

关键词： Polyolefin Nickel catalyst Diimine ligand Macrocyclic binuclear strategy Bimodal polyethylene

Photodegradable polar-functionalized polyethylenes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2023年第7期10卷 124-133页

作者： Chaoqun Wang jian Xia Yuxing Zhang Xiaoqiang Hu zhongbao jian State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences School of Applied Chemistry and Engineering University of Science and Technology of China

The degradation of plastics has attracted much attention from the global ***(PEs),as the most abundant synthetic plastics,are most frequently *** is non-degradable and non-polar because of the sole presence of the pure hydrocarbon *** incorporation of both in-chain cleavable and functional groups into the PE chain is an effective pathway to overcome the non-degradable and non-polar issue;however,the method for achieving this pathway remains ***,we report a strictly non-alternating(>99%) terpolymerization of ethylene with CO and fundamental polar monomers via a coordination-insertion mechanism using late transition metal catalysts,which effectively prevents the formation of undesired chelates originating from both co-monomers under a low CO ***-molecular-weight linear PEs with both in-chain isolated keto(>99%) and main-chain functional groups are *** incorporation of key low-content isolated keto groups makes PEs photodegradable while retaining their desirable bulk material properties,and the introduction of polar functional groups considerably improves their surface properties.

关键词： degradable plastic homogeneous catalysis C1 chemistry non-alternating copolymerization polyolefin

Photoresponsive α-Diimine Nickel Modulated Ethylene (Co)Polymerization

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2022年第24期40卷 2919-2926页

作者： Jingshuang Yang Xiaoqiang Hu zhongbao jian State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesRenmin Street 5625ChangchunJilin130022 China University of Science and Technology of China HefeiAnhui230026 China

Beyond the single ligand electronic and/or steric modifications, external stimuli are a useful tool for modulating catalytic polymerization reactions. Light stands out from external stimuli, but the corresponding photoresponsive transition metal catalysts are significantly rare for olefin polymerization due to the difficult synthesis. In this contribution, in consideration of the key role of steric shielding on the axial sites, we installed four concerted azobenzene moieties into symmetrically terphenyl-based α-diimine Ni(II) complexes to prepare photoresponsive catalysts, which were applied to ethylene polymerization and copolymerization with polar monomer. Via the trans-cis isomerization of azobenzene-functionalized Ni(II) catalysts in dark or under UV light, catalytic activity, polymer molecular weight, branching density, incorporation of co-monomer, and even the ratio of branching pattern were significantly modulated in ethylene (co)polymerizations. This photo-controlled strategy behaved an opposite influence between ethylene polymerization and copolymerization, in terms of catalytic activity and polymer molecular weight. As a result, slightly branched ultrahigh molecular weight polyethylenes and high molecular weight functionalized polyethylenes were produced at ambient conditions.

关键词： Olefin polymerization Photochemistry Polyethylene Polar monomer Nickel catalyst

Horizontally and Vertically Concerted Steric Strategy inα-Diimine Nickel Promoted Ethylene(Co)Polymerization

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2021年第10期39卷 2829-2836页

作者： Xiaoqiang Hu Yixin Zhang Baixiang Li zhongbao jian State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesRenmin Street 5625ChangchunJilin130022 China University of Science and Technology of China HefeiAnhui230026 China

Main observation and conclusion Steric bulk plays a significantly paramount role in late transition metal promoted olefin(co)polymerization in terms of polymer molecular weight and catalyst thermal *** sterically encumbered nickel and palladium catalysts have been developed,but they are usually *** this contribution,from a bi-directional side the distinctive horizontally and vertically concerted steric strategy was well-developed and applied toα-diimine nickel *** ethylene polymerization,the increase of vertically steric bulk(H,Ph,Biph)led to an enhanced polymer molecular weight,a slightly ascended branching density;likewise increasing horizontally steric bulk(Ph,Nap,Ant)further resulted in the increase of polymer molecular weight and branching *** a result,in sharp contrast to Ni1(H)without steric bulk,Ni5(Ant)with horizontally and vertically concerted steric bulk was thermally stable,showed very high activities at a level of 107 g·mol–1·h^(–1),and produced polyethylenes with the highest molecular weight of 518.8×10^(4)g·mol^(-1)and the broader range of branching density from 2.4/1000C to 27.8/*** the copolymerization of ethylene with methyl 10-undecenoate,Ni5(Ant)also provided the highest copolymer molecular weight but gave the lowest incorporation of *** work sheds light on the steric effect on olefin(co)polymerization.

关键词： Olefin polymerization Steric effect Homogeneous catalysis UHMWPE Nickel

Direct Synthesis of Ultrahigh Molecular Weight Functionalized Isotactic Polypropylene

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CCS Chemistry 2023年第11期5卷 2638-2649页

作者： Guanglin Zhou Hongliang Mu Xin Ma Xiaohui Kang zhongbao jian State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022 University of Science and Technology of China Hefei 230026 College of Pharmacy Dalian Medical UniversityDalian 116044

Ultrahigh molecular weight functionalized isotactic polypropylene(f-UHMW-iPP)through the direct copolymerization of propylene with polar monomers is highly desirable but has not been accessed thus far because it involves challenging regio-and stereochemistry along with usually reduced molecular ***,in contrast to the unsuccessful catalyst strategy,a polar monomer-assisted strategy is used to access the above *** introduction of O-or S-functionalized long-chain polar olefins into the hafnium-catalyzed copolymerization of propylene(and bulkierα-olefins)significantly increases the copolymer molecular weight with a maximum observed increase of+488%.f-UHMW-iPP and functionalized isotactic poly(α-olefin)s(M_(w)>2000 kDa,[mmmm]:99%)are thus prepared at ambient *** incorporation of 1 mol%of polar monomer improves the surface property and significantly increases the long-sought toughness(860%)of brittle iPP,without reducing the tensile strength(42 MPa)due to the key achievement of ultrahigh molecular weight.A discussion of the mechanism involved in the beneficial effects of incorporating the polar monomer is herein presented by an in-depth density functional theory calculation.

关键词： homogeneous catalysis olefin polymerization polar monomer ultrahigh molecular weight functionalized isotactic polypropylene

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CCS Chemistry 2022年第5期4卷 1680-1694页

作者： Xiaoqiang Hu Xiaohui Kang Yixin Zhang zhongbao jian State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022 University of Science and Technology of China Hefei 230026 College of Pharmacy Dalian Medical UniversityDalian 116044

The most straightforward and potentially ideal route to produce polar-functionalized polyethylene is direct copolymerization of ethylene with polar ***,access to high-molecular-weight polar copolymers represents one of the biggest challenges in the field of olefin *** this contribution,we report a family of well-designed nickel catalysts that readily address this issue under convenient and highly desired ambient *** 1 bar at 30℃,polar-functionalized ultrahigh number-average molecular weight polyethylenes(UHMWPEs,Mn=0.83-1.10×10^(6) g mol^(−1))are directly *** highest average number of incorporated polar units per polymer chain is *** enhances copolymer molecular weights by two orders of magnitude relative to previous ***,this nickel catalyst family also exceptionally produces the highest number-average molecular weight polyethylenes(Mn=6.04×10^(6) g mol^(−1))at 1 *** Sterimol B1 steric parameter of nickel catalyst quantitatively correlates to polymer molecular *** insights from density functional theory(DFT)calculation reveal that the low barrier(10.4 kcal mol^(−1))of ethylene insertion as the rate-limiting step should be responsible for high activity and the formation of *** coordination-insertion approach is a striking contrast to the high energy free-radical approach.

关键词： coordination polymerization functionalized UHMWPE homogeneous catalysis nickel catalyst polyolefin

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

空间位阻与氟效应协同增强镍系乙烯聚合

化学学报 2022年第6期80卷 741-747页

作者：王玉银胡小强穆红亮夏艳迟悦简忠保长春工业大学化学与生命科学学院高等材料研究院长春130012 长春工业大学材料科学与工程学院先进结构材料教育部重点实验室长春130012 中国科学院长春应用化学研究所高分子物理与化学国家重点实验室长春130022

烯烃聚合在工业上是最重要的化学反应之一.过渡金属催化剂是烯烃聚合反应发展的核心,其中水杨醛亚胺后过渡金属中性镍催化剂由于杂质耐受性强与无需助催化剂的双重优势备受青睐.为增强镍催化剂的催化性能,空间位阻效应或者氟效应策略已... 详细信息

烯烃聚合在工业上是最重要的化学反应之一.过渡金属催化剂是烯烃聚合反应发展的核心,其中水杨醛亚胺后过渡金属中性镍催化剂由于杂质耐受性强与无需助催化剂的双重优势备受青睐.为增强镍催化剂的催化性能,空间位阻效应或者氟效应策略已有广泛报道;然而将两者结合形成协同策略仍鲜有研究.在本工作中,对位氢和空间位阻取代基(苯基、萘基和蒽基)与邻位氟取代基被同时引入至水杨醛亚胺中性镍催化剂中,利用空间位阻效应与氟效应来协同增强镍系乙烯聚合.系统研究空间位阻效应、氟效应、聚合反应温度、聚合时间对乙烯聚合反应的活性、分子量、支化度的影响.结果表明,邻位氟取代基显著提升活性、催化剂寿命与聚合物分子量,降低聚合物支化度;对位空间位阻取代基的体积根据催化活性或聚合物分子量的需求而定,但对聚合物支化度几乎无影响.本工作发展了一种新的调控水杨醛亚胺镍烯烃聚合催化剂手段.

关键词：烯烃聚合氟效应空间位阻镍催化剂水杨醛亚胺

An Online Adaptive Internal Short Circuit Detection Method of Lithium-Ion Battery

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Automotive Innovation 2021年第1期4卷 93-102页

作者： jian Hu zhongbao Wei Hongwen He National Engineering Laboratory of Electric Vehicles School of Mechanical EngineeringBeijing Institute of Technology5 ZhongGuanCun South StreetHaidian DistrictBeijing 100181China

Internal short circuit(ISC)is a critical cause for the dangerous thermal runaway of lithium-ion battery(LIB);thus,the accurate early-stage detection of the ISC failure is critical to improving the safety of electric *** this paper,a model-based and self-diagnostic method for online ISC detection of LIB is proposed using the measured load current and terminal *** equivalent circuit model is built to describe the characteristics of ISC cell.A discrete-time regression model is formulated for the faulty cell model through the system transfer function,based on which the electrical model parameters are adapted online to keep the model ***,an online ISC detection method is exploited by incorporating an extended Kalman filter-based state of charge estimator,an abnormal charge depletion-based ISC current estimator,and an ISC resistance estimator based on the recursive least squares method with variant forgetting *** proposed method shows a self-diagnostic merit relying on the single-cell measurements,which makes it free from the extra uncertainty caused by other cells in the *** results suggest that the online parameterized model can accurately predict the voltage dynamics of *** proposed diagnostic method can accurately identify the ISC resistance online,thereby contributing to the early-stage detection of ISC fault in the LIB.

关键词： Lithium-ion battery Internal short circuit Recursive least squares Extended Kalman filter

CT 引导下细针辅助定位穿刺肺及肝内困难病灶

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国介入影像与治疗学 2024年第8期21卷 482-485页

作者：张建谭中宝狄镇海毛学群邹容王庆庆韩壮江苏大学附属医院介入放射科江苏镇江212000

目的观察CT引导下细针辅助定位穿刺肺及肝内困难病灶的可行性及安全性。方法回顾性纳入30例接受CT引导下22G穿刺针辅助定位穿刺的肺及肝内单发穿刺位置困难病灶或位置深在的直径0.5~2.0 cm病灶,记录辅助定位成功率、首次穿刺成功率及相... 详细信息

目的观察CT引导下细针辅助定位穿刺肺及肝内困难病灶的可行性及安全性。方法回顾性纳入30例接受CT引导下22G穿刺针辅助定位穿刺的肺及肝内单发穿刺位置困难病灶或位置深在的直径0.5~2.0 cm病灶,记录辅助定位成功率、首次穿刺成功率及相关并发症等。结果30个困难病灶包括27个肺内病灶、3个肝内病灶,平均直径(1.0±0.4)cm,均于CT引导下以22G穿刺针于靶病灶边缘、病灶旁1 cm或穿刺路径中辅助定位成功,定位成功率100%,未见明显并发症。后续操作包括对14个肺结节行术前穿刺定位、对10个肺结节和3个肝内病灶行穿刺活检及对3个肺结节实施微波消融,首次穿刺成功率100%。穿刺活检后3例(3/27,11.11%)肺内困难病灶患者出现少量气胸;未见其他明显并发症。结论CT引导下以细针辅助定位经皮穿刺肺及肝内困难病灶可行且安全。

关键词：肺疾病肝疾病穿刺术放射摄影术,介入性