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1.
双吡唑亚胺镍/甲基铝氧烷催化降冰片烯的聚合 总被引:1,自引:1,他引:0
合成了两种双吡唑亚胺镍配合物: 双-N-(苯基-1-3,5-二甲基吡唑基亚甲基)苯基亚胺二溴化镍(Cat.1)和双-4-甲氧基-N-(苯基-1-3,5-二甲基吡唑基亚甲基)苯基亚胺二溴化镍(Cat.2). 研究了Cat.1/MAO和Cat.2/MAO催化体系对降冰片烯(NBE)单体聚合的催化性能, 考察了各种聚合条件, 如温度、Al/Ni摩尔比及催化剂浓度对降冰片烯的催化效率、单体转化率、聚合物分子量及分子量分布的影响. 研究结果表明, Cat.1/MAO和Cat.2/MAO催化体系对降冰片烯聚合具有较高的催化效率, 可达到105 g PNBE/(mol Ni)数量级, 所得聚降冰片烯(PNBE)的重均分子量在105以上, 分子量分布指数在2左右. 聚合产物的1H NMR和FTIR谱分析结果表明, 该聚合反应是以单体的乙烯基加成聚合机理进行的. 相似文献
2.
A series of new nickel(II) complexes with 2-aminomethylpyridine ligands, (2-PyCH2NHAr)2NiBr2(Ar = 2,6-dimethylphenyl 2a; 2,6-diisopropylphenyl 2b, 2,6-difluorophenyl 2c), have been synthesized and used as catalyst precursors for ethylene polymerization in the presence of methylaluminoxane (MAO).The catalysts containing ortho-alkyl-substituents afford high molecular weight branched polyethylenes as well as a certain amount of oligomers. Enhancing the steric bulk of the alkyl substituent of the catalyst resulted in higher ratio of solid polymer to oligomer and higher molecular weight of the polymer. Catalyst 2c containing ortho-fluoro-substituents exhibited the highest catalytic activity, but only oligomers in which C12H24 had the maximum content were obtained by the catalyst. The molecular weight, molecular weight distribution, and microstructure of the resulted polymer were characterized by gel permeation chromatography and 13C-NMR spectrogram. 相似文献
3.
Single and binary catalyst systems based on nickel and palladium in polymerization of ethylene 下载免费PDF全文
The catalyst (N,N‐bis(2,6‐dibenzhydryl‐4‐ethoxyphenyl)butane‐2,3‐diimine)nickel dibromide, a late transition metal catalyst, was prepared and used in ethylene polymerization. The effects of reaction parameters such as polymerization temperature, co‐catalyst to catalyst molar ratio and monomer pressure on the polymerization were investigated. The α‐diimine nickel‐based catalyst was demonstrated to be thermally robust at a temperature as high as 90 °C. The highest activity of the catalyst (494 kg polyethylene (mol cat)?1 h?1) was obtained at [Al]/[Ni] = 600:1, temperature of 90 °C and pressure of 5 bar. In addition, the performance of a binary catalyst using nickel‐ and palladium‐based complexes was compared with that of the corresponding individual catalytic systems in ethylene polymerization. In a study of the catalyst systems, the average molecular weight and molecular weight distribution for the binary polymerization were between those for the individual catalytic polymerizations; however, the binary catalyst activity was lower than that of the two individual ones. The obtained polyethylenes had high molecular weights in the region of 105 g mol?1. Gel permeation chromatography analysis showed a narrow molecular weight distribution of 1.44 for the nickel‐based catalyst and 1.61 for the binary catalyst system. The branching density of the polyethylenes generated using the binary catalytic system (30 branches/1000 C) was lower than that generated using the nickel‐based catalyst (51/1000 C). X‐ray diffraction study of the polymer chains showed higher crystallinity with lower branching of the polymer obtained. Also Fourier transform infrared spectra confirmed that all obtained polymers were low‐density polyethylene. 相似文献
4.
α-萘基丁二亚胺氯化镍/MAO制备双(宽)峰聚乙烯 总被引:5,自引:0,他引:5
合成了一种新型α 二亚胺镍配合物———α 萘基丁二亚胺氯化镍 ,此配合物作为催化剂在MAO的活化下催化乙烯聚合得到支化聚乙烯 ,聚合活性高达 7 18× 10 5gPE molNi·h ,1 3C NMR、FTIR测试结果表明制备的聚乙烯含有末端双键 ;GPC结果表明所制备的聚乙烯分子量呈双 (宽 )峰分布 ,其原因有两个 ,一是此催化剂能产生分子量较低的α 烯烃 ,在聚合过程中一部分α 烯烃会“就地”与乙烯原位共聚形成分子量较高的聚合物 ,二是此催化剂存在立体异构体 ,而不同异构体在MAO活化下形成的活性中心的配位环境不同 ,因而得到的聚乙烯的分子量也不同 .研究了聚合温度、聚合压力、铝镍摩尔比 (nAl nNi)对催化活性、聚乙烯分子量、支化度的影响 .聚乙烯的分子量随聚合温度的升高而下降 ,支化度增大 ,熔点则降低 . 相似文献
5.
孙文华 State Key Laboratory of Engineering Plastics The Center for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences Beijing China 《高分子科学》2003,(4):453-457
8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp_2ZrCl_2) were supportedsimultaneously on silica to produce branched polyethylene successfully by combined polymerization. The supportedpolymerization results showed that the molecular weight of polyethylene increased while the molecular weight distributionbecame wider and the molecular chains of oligomers remaning in the final solution became shorter as compared to theoligomers obtained in polymerization processes with pure 8-aminoquinoline nickel dichloride catalysis, as well as theCp_2ZrCl_2 and nickel combination system. With decreasing amount of Ni catalyst in the supported catalyst, the molecular chains of oligomers in the resulting solution became shorter, while α-olefin selectivity increased. 相似文献
6.
T. Higashimura T. Matsuda S. Okamura 《Journal of polymer science. Part A, Polymer chemistry》1970,8(2):483-493
The molecular weight distribution of poly-N-vinylcarbazole (PVCar) obtained in solid-state polymerization with various catalysts or γ-rays was measured by gel-permeation chromatography, in order to determine the mechanism of the solid-state polymerization. In addition, the molecular weight distribution of PVCar obtained in the solution polymerization by the cationic catalyst was also measured. The molecular weight distribution of PVCar obtained in the catalytic solid-state polymerization was broad and had three peaks, independent of the nature of catalysts, radical and cationic. A large amount of low molecular weight oligomer (probably dimer or trimer) was formed in the catalytic solid-state polymerization of VCar. The molecular weight distribution of PVCar obtained in the cationic solution polymerization showed only one sharp peak. On the other hand, the molecular weight of PVCar obtained in the radiation-induced solid-state polymerization was larger than that obtained in the catalytic solid-state polymerization, and dimer or trimer was not formed. The molecular weight distribution of PVCar obtained was composed of one sharp peak in the high molecular weight region, and a broad peak in the low molecular weight region, and was extremely different from that of PVCar obtained in the catalytic solid-state polymerization. 相似文献
7.
Duquesne E Degée P Habimana J Dubois P 《Chemical communications (Cambridge, England)》2004,(6):640-641
A new supported catalytic system, i.e. nickel bromide catalyst ligated by triphenylphosphine (TPP) ligands immobilized onto crosslinked polystyrene resins (PS-TPP) is reported. Per se, this catalyst does not allow any control over the polymerization of methyl methacrylate (MMA) initiated by ethyl 2-bromoisobutyrate but, in the presence of a given amount of purposely added free TPP, it promotes controlled ATRP of MMA. Indeed colorless PMMA chains of low polydispersity indices are readily recovered, the molecular weight of which linearly increases with monomer conversion and agrees with the expected values. Recycling of the supported catalyst is evidenced and does not prevent the polymerization from being controlled. 相似文献
8.
9.
Hao Zou Fangming Zhu Qing Wu 《Journal of polymer science. Part A, Polymer chemistry》2008,46(6):2186-2192
The copolymerization of ethylene with cyclopentene catalyzed by three α‐diimine nickel(II) complexes in the presence of methylaluminoxane (MAO) was investigated. High‐molecular‐weight branched ethylene/cyclopentene copolymers with only cis‐1,3‐enchained cyclopentene units, which has not been reported previously, were obtained. The catalytic activity, cyclopentene incorporation, copolymer molecular weight, and molecular‐weight distribution could be controlled over a wide range through the variation of the catalyst structure and polymerization conditions, including cyclopentene concentration in the feed and polymerization temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2186–2192, 2008 相似文献
10.
A series of new nickel(Ⅱ)complexes with 2-aminomethylpyridine ligands,(2-PyCH_2NHAr)_2NiBr_2(Ar=2,6- dimethylphenyl 2a;2,6-diisopropylphenyl 2b,2,6-difluorophenyl 2c),have been synthesized and used as catalyst precursors for ethylene polymerization in the presence of methylaluminoxane(MAO).The catalysts containing ortho-alkyl-substituents afford high molecular weight branched polyethylenes as well as a certain amount of oligomers.Enhancing the steric bulk of the alkyl substituent of the catalyst resulted... 相似文献
11.
双组分茂金属催化剂催化乙烯聚合的研究 总被引:1,自引:0,他引:1
选择能形成支链的不对称桥联茂金属化合物Me2 C[(Cp) (Ind) ]ZrCl2 和非桥联的不同结构的茂金属化合物二氯二 (烯基取代环戊二烯 )锆如 ( Cp) 2 ZrCl2 ,(Cp) 2 ZrCl2 和 (Cp) 2 ZrCl2 ,以MAO为助催化剂 ,分别组成三组双组分茂金属催化剂的催化体系 ,催化乙烯聚合 .结果表明 ,两类催化剂组成的双组分茂金属催化体系催化乙烯聚合能得到支化的宽分子量分布的聚乙烯 ;聚合温度和改变两种茂金属催化剂的摩尔比对催化活性和分子量有很大影响 .因此可以利用改变双组分茂金属催化剂的摩尔比例和聚合温度来调控聚合物的分子量和分子量分布 .改变两种茂金属催化剂的摩尔比和聚合温度也能使聚合物的结晶度发生改变 相似文献
12.
Naphthyl-α-diimine nickel complexes with systematically varied ligand sterics, activated by modified methylaluminoxane(MMAO), were tested in the polymerization of higher α-olefin(1-hexene, 1-decene and 1-hexadecene) under suitable conditions. The polymerization results indicated the possibility of precise microstructure control, depending on catalyst structure, polymerization temperature, monomer concentration and types of monomers, which in turn strongly affects the resultant polymer properties. Naphthyl-α-diimine nickel complex bearing chiral bulky sec-phenethyl groups in the o-naphthyl position showed good catalytic activity, and resulted in branched polymers(42-88/1000 C) with high molecular weights(M_n:(4.3-15.2) × 10~4 g·mol~(-1)) and narrow molecular weight distribution(M_w/M_n = 1.13-1.29, RT), which suggested a living polymerization. The increasing steric hindrance of catalyst leads to enhance insertion for 2,1-insertion of α-olefin and the chain-walking reaction. 相似文献
13.
Zhong Xi Huang Yong Ming Zhang Hong Li Ying Hao Luan Yan Gang Liu 《Journal of polymer science. Part A, Polymer chemistry》2008,46(4):1416-1426
Ion exchange resin immobilized Co(II) catalyst with a small amount of soluble CuCl2/Me6TREN catalyst was successfully applied to atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in DMF. Using this catalyst, a high conversion of MMA (>90%) was achieved. And poly(methyl methacrylate) (PMMA) with predicted molecular weight and narrow molecular weight distribution (Mw/Mn = 1.09–1.42) was obtained. The immobilized catalyst can be easily separated from the polymerization system by simple centrifugation after polymerization, resulting in the concentration of transition metal residues in polymer product was as low as 10 ppm. Both main catalytic activity and good controllability over the polymerization were retained by the recycled catalyst without any regeneration process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1416–1426, 2008 相似文献
14.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(46):14864-14868
The transition‐metal‐catalyzed copolymerization of olefins with polar functionalized co‐monomers represents a major challenge in the field of olefin polymerization. It is extremely difficult to simultaneously achieve improvements in catalytic activity, polar monomer incorporation, and copolymer molecular weight through ligand modifications. Herein we introduce a polyethylene glycol unit to some phosphine‐sulfonate palladium and nickel catalysts, and its influence on ethylene polymerization and copolymerization is investigated. In ethylene polymerization, this strategy leads to enhanced activity, catalyst stability, and increased polyethylene molecular weight. In ethylene copolymerization with polar monomers, improvements in all copolymerization parameters are realized. This effect is most significant for polar monomers with hydrogen‐bond‐donating abilities. 相似文献
15.
Haiyang Gao Junkai Zhang Yan Chen Fangming Zhu Qing Wu 《Journal of molecular catalysis. A, Chemical》2005,240(1-2):178-185
Herein reported are investigations of norbornene polymerization by novel anilido–imino nickel complexes [(Ar1NCHC6H4NAr2)NiBr]2 (Ar1 = Ar2 = 2,6-dimethylphenyl, 1; Ar1 = 2,6-dimethylphenyl, Ar2 = 2,6-diisopropylphenyl, 2; Ar1 = Ar2 = 2,6-diisopropylphenyl, 3; Ar1 = 2,6-diisopropylphenyl, Ar2 = 2,6-dimethylphenyl, 4) activated with methylaluminoxane (MAO). It was found that at polymerization temperatures below 50 °C, the average molecular weights of the obtained polynorbornenes catalyzed by these four catalytic systems increase with raising temperature, displaying bimodal distribution in GPC curves. The abnormal influence of polymerization temperature could be attributed to the existence of two kinds of catalytic species: heterobimetallic species LNi(II)(μ-Me)2AlMe2 (I) and monometallic species LNi(II)Me (II) (L = anilido–imino ligand) at lower temperature. The former affords a lower molecular weight polymer and the latter higher molecular weight one. With raising polymerization temperature above 50 °C, the species I disappears and only species II exists in polymerization systems, resulting in a normal relation of molecular weight to polymerization temperature. From a kinetic study of the norbornene polymerization catalyzed by 1/MAO catalyst at 70 °C, the polymerization rate (Rp) can be expressed by the formulation: Rp = k[NBE]1.93[Ni]0.88. Moreover, the mechanism of the norbornene polymerization using the anilido–imino nickel complexes activated with MAO is also presented and discussed. 相似文献
16.
《中国化学快报》2022,33(9):4363-4366
The tuning of olefin-polymerization catalyst properties through ligand modifications is efficient but requires complicated and costly syntheses. In this contribution, a simple Bu2Mg-based cocatalyst strategy is designed that can simultaneously enhance the catalytic properties (activity, thermal stability, polymer molecular weight, branching density, melting point, etc.) of various nickel catalysts (α-diimine nickel, pyridine imine nickel and iminopyridine-N-oxide nickel) in ethylene polymerization, and enable great product morphology control. For example, a simple α-diimine nickel catalyst can demonstrate polymerization activity of up to 1.29×107 g mol?1 h?1 and molecular weight of up to 1.90×106 g/mol in the presence of Bu2Mg cocatalyst. The resulting polyethylenes exhibit excellent mechanical properties, with tensile stress of up to 47.4 MPa and strain of up to 1020%. This cocatalyst strategy is generally applicable to different nickel catalysts, and can lead to property enhancement in ethylene copolymerization with a series of polar comonomers such as methyl 10-undecylenate, 10-undecylenic acid and 10-undecenol. 相似文献
17.
The polymerization of methyl methacrylate (MMA) was investigated using a series of bis(β‐ketoamino)nickel(II) complexes in combination with methylaluminoxane in toluene solution. The binary catalyst is necessary for initiating MMA polymerization and producing PMMA with high molecular weights but broad molecular weight distributions. The effects of reaction temperature and Al:Ni molar ratios on the polymerization of MMA were examined in detail. Both steric bulk and electronic effects of the substituents around the imino group in the ligand on MMA polymerization activities could be observed. Relative to electronic effects, the steric hindrance of the ligands displayed a more significant effect on the catalytic activities, with the catalytic activity sequence observed in the order 4 > 1 > 2 > 3 > 5 > 6. Structural analyses of the polymers by 13C NMR spectra indicate that polymerization yields PMMA with a syndiotactic‐rich atactic microstructure. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
18.
Kittichote Musikabhumma Thomas P. Spaniol Jun Okuda 《Journal of polymer science. Part A, Polymer chemistry》2003,41(4):528-544
The synthesis of branched polyethylenes by ethylene polymerization with new tandem catalyst systems consisting of methylaluminoxane‐preactivated linked cyclopentadienyl‐amido titanium catalysts [Ti(η5:η1‐C5Me4SiMe2NR)Cl2 (R = Me or tBu)] supported on pyridylethylsilane‐modified silica (PySTiNMe and PySTiNtBu) and homogeneous dibromo nickel catalyst having a pyridyl‐2,6‐diisopropylphenylimine ligand (PyminNiBr2) in the presence of modified methylaluminoxane was investigated. Ethylene polymerization with only PyminNiBr2 yielded a mixture of 1‐ and 2‐olefin oligomers with methyl branches [weight‐average molecular weight (Mw) ~ 460)] with a ratio of about 1:7. By the combination of this nickel catalyst with PySTiNtBu, polyethylenes with long‐chain branches (Mw = 15,000–50,000) were produced. No incorporation of 2‐olefin oligomers was observed in the 13C NMR spectra. Unexpectedly, the combination of the nickel catalyst with PySTiNMe produced lower molecular weight polyethylenes with only methyl branches. The molecular weight distributions of branched polyethylenes obtained with both PySTiNMe and PySTiNtBu combined with the nickel catalyst were broad (weight‐average molecular weight/number‐average molecular weight < 9). Bimodal gel permeation chromatography (GPC) curves were clearly observed in the PySTiNMe system, whereas GPC curves with small shoulders in low molecular weight areas were observed for PySTiNtBu. The synthesis of branched polyethylenes with tandem catalyst systems of corresponding homogeneous titanium catalysts and the nickel catalyst was also investigated for comparison. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 528–544, 2003 相似文献
19.
The catalytic system of[2-(2-benzimidazolyl)-6-((1-aryliminoethyl)pyridyl)]nickel chloride/MAO(methylalu- minoxane)was found to be good active for vinyl polymerization of norbornene and provided polymers with relative narrow molecular distributions.Various reaction parameters,such as the ratios of nickel precursor to MAO or monomer norbornene, and the nature of the ligands in complexes were carefully investigated to realize their effects on the catalytic activities, polymer molecular weight and molecular... 相似文献
20.
Isshin Murayama Kazuhiro Yamamoto Tsutomu Sakuragi Kenji Iiba Miru Hirahara Hitoshi Ogihara Hideki Kurokawa 《大分子反应工程》2019,13(4)
The complex [N‐(2,6‐diisopropylphenyl)‐2‐(2,6‐diisopropylphenylimino)‐propanamidato‐κ2N,O](η1‐benzyl)nickel(lutidine) is immobilized on an acid‐treated montmorillonite. When the montmorillonite is treated with alkylaluminum, the catalyst shows a high activity with high molecular‐weight polyethylene. The catalytic behavior of the polymerization suggests isomerization of the complex on acid sites of the support surface. 相似文献