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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. 相似文献
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《高分子学报》2021,52(5):531-540
相比于烯烃聚合过渡金属催化剂的空间位阻与电子效应,氟效应是一种简单且有效调控烯烃聚合反应的重要方法,但研究却相对较少.在本工作中,通过把不同位置(邻、间、对)和不同数目(0、1、2、3、5)的氟原子引入到N,O配位型的单组分阳离子酮亚胺镍催化剂中,系统地考察了氟效应对乙烯聚合反应的催化活性、催化剂热稳定性、聚合物分子量以及聚合物支化度的全面影响.发现邻位氟取代基有利于聚合物分子量的显著提高,而间位与对位氟取代基导致聚合活性下降;特别是全氟取代基不仅造成催化剂热稳定性的下降,同时导致聚合活性与聚合物分子量的大幅下降.在乙烯与丙烯酸甲酯的共聚合研究中,无氟取代的镍催化剂出现失活,但邻氟取代的镍催化剂则表现出聚合活性以及赋予共单体插入率,这些行为在长链极性单体共聚中表现更加优异.本工作有助于理解氟效应在烯烃聚合中的重要作用. 相似文献
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《高分子通报》2021,(6):81-93
后过渡金属α-二亚胺镍钯聚合催化剂由于其单中心、高活性以及良好的极性基团容忍性,能够直接催化乙烯和极性单体共聚而引起广泛的关注。但此类催化剂的热稳定性差,远未达到工业上气相聚合生产对高温的要求,限制了其进一步的产业化应用。先前报道的提高催化剂热稳定性的策略主要集中在苯胺的邻位位阻修饰上。不同于先前的策略,本课题组采用增加骨架位阻的策略,也能够有效提高催化剂的热稳定性和聚合的可控性。本文主要介绍了本课题组近期大位阻骨架策略在α-二亚胺镍钯烯烃聚合催化剂中的应用,包括乙烯聚合、α-烯烃聚合、乙烯和极性单体共聚、苯乙烯类单体聚合以及一氧化碳和苯乙烯的交替共聚。 相似文献
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烯烃高效催化剂及聚合与共聚合的研究 总被引:1,自引:0,他引:1
为中山大学高分子研究所烯烃配位聚合研究室在高效Ziegler-Natta催化剂、茂金属催化剂烯烃聚合与共聚合方面部分研究工作的概述。重点叙述了催化剂的设计、过渡金属配合物配体结构及聚合条件对乙烯、丙烯、1-丁烯、丁二烯、苯乙烯等烯烃单体聚合及共聚合活性以及聚合产物结构和分子量的影响。 相似文献
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《分子科学学报》2021,(4)
以γ-氨丙基三乙氧基硅烷和水杨醛为原料,通过席夫碱反应合成一类硅烷基Schiff碱亚胺配体;分别以六水氯化镍和六水氯化钴为络合试剂,通过络合反应合成两类硅烷基Schiff碱亚胺络合过渡金属催化剂.元素分析、FT-IR、~1H NMR和ICP证实合成的硅烷基Schiff碱亚胺配体及其相应的过渡金属催化剂的结构与其理论结构相符.两类硅烷基Schiff碱亚胺络合过渡金属催化剂具有良好的催化乙烯齐聚活性,且其催化性能不仅受助催化剂结构和主催化剂活性中心种类的影响,而且还受聚合反应参数的影响.甲基铝氧烷(MAO)为助催化剂,环己烷为溶剂时,聚合活性和齐聚产物中C_8以上烯烃的含量较高;当Al/Co物质的量比为500、反应温度为25℃、反应压力为0.5 MPa和反应时间为30 min时,硅烷基Schiff碱亚胺络合钴催化剂催化乙烯齐聚的活性为1.13 g·μmol~(-1)·h~(-1),齐聚产物中C_8以上烯烃含量为52.70%.受电子云密度的影响,硅烷基Schiff碱亚胺络合镍催化剂的催化活性高于相应的钴催化剂. 相似文献
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烯烃与极性单体共聚制备功能化聚烯烃最为直接,但存在诸多挑战,是聚烯烃领域近20年的研究热点与难点。后过渡金属催化剂在功能化聚烯烃合成上具有优势,已经涌现出了二亚胺、水杨醛亚胺、膦磺酸镍钯经典催化体系;相比之下,膦酚镍催化体系早期关注较少。然而,近期对于膦酚镍催化体系的研究已经揭示,膦酚镍催化体系将是一个极具基础与应用前景的体系。本文总结近5年膦酚镍催化剂的结构特点,综述其在乙烯聚合、乙烯与极性单体共聚合、丙烯与极性单体共聚合方面的重要进展,并总结出膦酚镍催化剂的优势,对极性单体种类、催化剂结构设计、丙烯与极性单体立构规整共聚、聚合反应机理、功能化聚烯烃综合性能进行了展望。 相似文献
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Yu-Yin Wang Chao-Qun Wang Xiao-Qiang Hu Yan Xia Yue Chi Yi-Xin Zhang Zhong-Bao Jian 《高分子科学》2021,39(8):984-993
For the rational design of metal catalyst in olefin polymerization catalysis, various strategies were applied to suppress the chain transfer by bulking up the axial positions of the metal center, among which the "sandwich" type turned out to be an efficient category in achieving high molecular weight polyolefin. In the α-diimine system, the "sandwich" type catalysts were built using the typical 8-aryl-naphthyl framework. In this contribution, by introducing the rotationally restrained benzosuberyl substituent into the ortho-position of N-aryl rings, a new class of "sandwich-like" α-diimine nickel catalysts was constructed and fully identified. The rotationally restrained benzosuberyl substituents played a "sandwich-like" function by capping the nickel center from two axial sites. Compared to the nickel catalyst Ni1 bearing freely rotated benzhydryl substituent, Ni2 featuring benzosuberyl substituent enabled the increase(8 times) of polymer molecular weights from 8 kDa to 65 kDa in the polymerization of ethylene. By further increasing the steric bulk of another ortho-site of the N-aryl ring, the polymer molecular weight even reached an ultrahigh level of 833 kDa(M_w=1857 kDa) using the optimized Ni3. Notably, these nickel catalysts could also mediate the copolymerization of ethylene with methyl 10-undecenoate, with Ni3 giving the highest copolymer molecular weight(88 kDa) and the highest incorporation of comonmer(2.0 mol%), along with high activity of up to 10~5 g·mol~(-1)·h~(-1). 相似文献
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新型后过滤金属烯烃聚合催化剂——镍系烯烃聚合催化剂 总被引:1,自引:1,他引:1
镍系烯烃聚合催化剂是近年来受到广泛关注的一类新型催化剂,是配位催化研究的热点之一。这类催化剂具有高催化活性、单活性中心和良好的分子剪栽性,可以在分子层次上实现烯烃聚合的分子设计与组装。本文介绍了镍系烯烃聚合催化剂的发展和研究概况,并评述了聚合特性及最新研究进展。 相似文献
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新型后过渡金属烯烃聚合催化剂--镍系烯烃聚合催化剂* 总被引:1,自引:0,他引:1
镍系烯烃聚合催化剂是近年来受到广泛关注的一类新型催化剂,是配位催化研究的热点之一。这类催化剂具有高催化活性、单活性中心和良好的分子剪栽性,可以在分子层次上实现烯烃聚合的分子设计与组装。本文介绍了镍系烯烃聚合催化剂的发展和研究概况,并评述了聚合特性及最新研究进展。 相似文献
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Bijal Kottukkal Bahuleyan Dae-Won Park Chang-Sik Ha Il Kim 《Catalysis Surveys from Asia》2006,10(2):65-73
In this review article, we have consolidated our recent studies on late transition metal catalysts (mainly Fe, Co) for olefin polymerization/oligomerization. A series of bisiminopyridyl Co(II) and Fe(II) complexes were synthesized. These catalysts when activated with MAO in aromatic or aliphatic hydrocarbon solvents, oligomerize or polymerize ethylene to α-olefins or high molecular weight polymers with exceptionally high activities and selectivities. The electronic and steric effects of allyloxy and benzyloxy substituted bisiminopyridyl Fe(II) and Co(II) complexes were also investigated. The influence of catalyst structure and temperature on the polymerization activity, thermal properties and molecular weight were discussed. The effects of heterogenization of these catalysts on silica and modified SBA-15 were analyzed. The polymerization of polar monomers such as vinyl ethers and methyl methacrylate was tested and no specific trends in activity and polymer molecular weight with changes in steric bulkiness around the metal center were observed with the same catalyst system. 相似文献
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简要叙述我国近20年来在高分子化学研究领域中的自由基聚合、光诱导聚合、Ziegler Natta聚合和茂金属聚烯烃、环醚、枘酯等开环聚合、缩聚反应合成PEEK和耐热性杂环高分子含氟高分子、生物医学高分子、导电高分子、液晶高分子方面的进展。 相似文献
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Rieko Furuyama 《Journal of organometallic chemistry》2005,690(20):4398-4413
Based on new results as well as the reported data, the ethylene and propylene polymerization behavior of bis(phenoxy-imine) Ti complexes (Ti-FI Catalysts) combined with MAO (particularly that of their fluorinated versions) is discussed, with an emphasis on the characteristics and mechanisms of living ethylene and syndioselective living propylene polymerization. Unlike common living olefin polymerization catalysts, fluorinated Ti-FI Catalysts with MAO display thermally robust living behavior and polymerize ethylene in a highly controlled manner at temperatures as high as 50 °C. Additionally, despite being C2-symmetric catalysts, fluorinated Ti-FI Catalysts/MAO mediate highly syndioselective living propylene polymerization. Fluorinated Ti-FI Catalysts that we developed are the first examples of catalysts that induce the living polymerization of both ethylene and propylene. In addition, they are also the first examples of living and, at the same time, highly stereoselective propylene polymerization catalysts. The versatile and robust living nature of the fluorinated Ti-FI Catalysts allows the preparation of a wide variety of unique living polymers; some of which can even be produced catalytically. On the basis of theoretical calculations as well as experimental results, we conclude that these unusual polymerization features of fluorinated Ti-FI Catalysts originate from an attractive interaction between the ligand and a growing polymer chain and/or the fluxional character of the catalyst coupled with 2,1-regiochemistry. This is in stark contrast to group 4 metallocene catalysts, which control olefin polymerization mainly by repulsive interactions based on the rigidly organized ligand frameworks. 相似文献