This study synthesized α-diimine nickel catalysts featuring two and three hydroxyl groups (Cat1 and Cat2), along with their corresponding supported catalysts (S-Cat1 and S-Cat2). These catalysts demonstrated high activity in ethylene polymerization, reaching up to 7 × 106 g/molNi·h, yielding polyethylenes with tunable molecular weights (174–553 kg/mol), branching degrees (38–140/1000 C) and higher elongation at break (up to 1230

Ti3C2Tx MXene/CuxO composites were prepared by acid etching combined with electrochemical technique. The abundant active sites on the surface of MXene greatly increase the loading of CuxO nanoparticles, and the synergistic effect between the different components of the composite can accelerate the oxidation reaction of glucose. The results indicate that at the working potential of 0.55 V (vs. Ag/AgCl), the glucose sensor based on Ti3C2Tx MXene/CuxO composite presents large linear concentration ranges from 1 µM to 4.655 mM (sensitivity of 361 µA mM−1 cm−2) and from 5.155 mM to 16.155 mM (sensitivity of 133 µA mM−1 cm−2). The limit of detection is 0.065 µM. In addition, the sensor effectively avoids the oxidative interference of common interfering species such as ascorbic acid, dopamine and uric acid. The sensor has good reproducibility, stability and acceptable recoveries for the detection of glucose in human sweat sample (97.5-103.3

The α-diimine late transition metal catalyst represents a new strategy for the synthesis of atactic polypropylene elastomer. Taking into account the properties of the material, enhancing the molecular weight of polypropylene at an elevated temperature through modifying the catalyst structure, and further increasing the activity of α-diimine catalyst for propylene polymerization, are urgent problems to be solved. In this work, two α-diimine nickel(II) catalysts with multiple hydroxymethyl phenyl substituents were synthesized and used for propylene homopolymerization. The maximum catalytic activity was 5.40 × 105 gPP/molNi·h, and the activity was still maintained above 105 gPP/molNi·h at 50 °C. The large steric hindrance of catalysts inhibited the chain-walking and chain-transfer reactions, resulting in polypropylene with high molecular weights (407~1101 kg/mol) and low 1,3-enchainment content (3.57~16.96%) in toluene. The low tensile strength (0.3~1.0 MPa), high elongation at break (218~403%) and strain recovery properties (S.R. ~50%, 10 tension cycles) of the resulting polypropylenes, as well as the visible light transmittance of approximately 90%, indicate the characteristics of the transparent elastomer.

For covalent attachment-supported α-diimine catalysts, on the basis of ensuring the thermal stability and activity of the catalysts, the important problem is that the active group on the catalyst can quickly react with the support, anchoring it firmly on the support, shortening the loading time, reducing the negative impact of the support on the active centers, and further improving the polymer morphology, which makes them suitable for use in industrial polymerization temperatures. Herein, we synthesized a α-diimine nickel(II) catalyst bearing four hydroxyl substituents. The hydroxyl substituents enable the catalyst to be immobilized firmly on silica support by covalent linkage in 5–10 min. Compared with the toluene solvent system, the homogeneous catalysts show high activity and thermal stability in hexane solvent at the same conditions. Compared with homogeneous catalysts, heterogeneous catalysis leads to improvements in catalyst lifetime, polymer morphology control, catalytic activity, and the molecular weight of polyethylene (up to 679 kg/mol). The silica-supported catalysts resulted in higher melting temperatures as well as lower branching densities in polyethylenes. Even at 70 °C, the polyethylene prepared by S-CatA-2 still exhibits dispersed particle morphology, and there is no phenomenon of reactor fouling, which is suitable for industrial polymerization processes.

To improve the thermal stabilities and polymerization activities of α-diimine nickel catalysts, two asymmetric nickel complexes, Cat1 and Cat2, bearing large steric hindrance fluorine-containing diphenylmethyl substituents were designed, synthesized and used for ethylene polymerization. These two homogeneous catalysts exhibited good thermal stability, especially Cat2, which exhibited an activity of 2.04 × 106 gPE/molNi h at 80 °C. To control the polymer particle morphology and avoid the fouled reactor, these α-diimine catalysts were covalently bonded to modified silica supports, and two supported α-diimine catalysts, S-Cat1 and S-Cat2, were prepared for ethylene polymerization. The particle morphology of the polyethylene was substantially improved. Additionally, the melting point of the polyethylene was increased to approximately 110–120 °C. The molecular weight of the polymer prepared with the supported catalyst was nearly twice that of the polymer catalyzed by the corresponding homogeneous catalyst, and the molecular weight of the polyethylene prepared by S-Cat2 reached 1790 kg/mol. The substituents on the ligands affected the properties of the α-diimine nickel catalysts and the microstructure of the resulting polyethylene.

Four supported α-diimine nickel(II) catalysts covalently linked to silica via hydroxyl functionality on α-diimine acenaphthequinone-backbone were prepared and used in slurry polymerizations of ethylene to produce branched polyethylenes. The catalytic activities of these still reached 106 g/molNi·h at 70 °C. The life of the supported catalyst is prolonged, as can be seen from the kinetic profile. The molecular weight of the polyethylene obtained by the 955 silica gel supported catalyst was higher than that obtained by the 2408D silica gel supported catalyst. The melting points of polyethylene obtained by the supported catalysts S-C1-a/b are all above 110 °C. Compared with the homogeneous catalyst, the branching numbers of the polyethylenes obtained by the supported catalysts S-C1-a/b is significantly lower. The polyethylenes obtained by supported catalyst S-C1-a/b at 30–50 °C are free-flowing particles, which is obviously better than the rubber-like cluster polymer obtained from homogeneous catalyst.

设计并合成了两种苊环带有羟基、苯胺上带有不同取代基的α-二亚胺Ni(Ⅱ)催化剂Cat-F和Cat-OCH3,研究了两种催化剂在一铝二乙基铝的作用下催化乙烯均聚的催化性能.研究表明,温度和压力对催化剂活性的影响较大.此外,采用差示扫描量热仪(DSC)、碳谱核磁(13C-NMR)、凝胶渗透色谱(GPC)等仪器对聚合产物进行了测试,分析了聚合条件对聚乙烯的熔点、支化度、平均分子量及其分布的影响.

A series of 1-butene/pentafluorophenylundec-1-ene ester random copolymers were synthesized under the Ziegler-Natta catalyst system. The content of the pentafluorophenyl (PFP) group in the copolymer can reach up to 0.59 mol%. The DSC test found that the PFP groups attached to the PB main chain retard the crystalline transformation of Form II to Form I. Nucleophilic aromatic substitutions of pentafluorophenyl ester occurred with biocompatible poly(ethylene glycol) methyl ether (mPEG) introduced into the side chain of PB under very mild conditions. The results show that not only is the crystallization rate of mPEG functionalized PB increased, but also Tm, Tc, χc and the crystalline phase transition rate of Form II to Form I are also enhanced. Among them, mPEG with a Mn of 500 has the best promoting effect. On the other hand, the hydrophilicity of mPEG-functionalized PB is improved, and it is proportional to the chain length of mPEG. However, the experimental results show that the regularity of the PB structure is the determinant of the rate of crystallization and phase transition.

In order to promote development of linear/branched block polyethylenes based on new catalytic systems, we synthesized a novel α-diimine nickel(II) complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-N-aryl structures. The activity of α-diimine nickel(II) catalyst was 3.02×106 g·molNi−1·h−1 at 70 °C, and resultant polyethylene possessed 135/1000C branches. The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the α-diimine nickel(II) complex/bis(phenoxyimine) zirconium in the presence of diethyl zinc. With the addition of ZnEt2 (from 0 to 400), the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting peaks. The molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained via adjusting ZnEt2 equiv. and molar ratio of two catalysts. In addition, the branching degree of the polyethylene increased from 13/1000C to 56/1000C with the increase of the proportion of α-diimine nickel(II) catalyst. Using this binary catalyst system, the reaction temperature of chain shuttling polymerization can be carried out at 70 °C, which is more conducive to industrial application.

In order to promote the thermostability of α-diimine nickel complex by ligand backbone structure, a series of α-diimine nickel complexes with substituents on acenaphthequinone backbone were synthesized and used as catalysts for ethylene polymerization. When the hydroxyethyl phenoxyl group was introduced to the acenaphthequinone-backbone, the thermal stability and activity of the catalyst could be significantly improved. The catalytic activity of complex C2 [5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-diisopropyl)acenaphthylene-1,2-diimine]nickel(II) dibromide with isopropyl substituents on N-aryl reached 8.2 × 106 g/(molNi·h) at 70 °C and 2 MPa. The activity of [5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-dibenzhydryl-4-menthylphenyl)acenaphthylene-1,2-diimine]nickel(II) dibromide (C3) still maintained at 6.7 × 105 g/(molNi·h) at 120 °C. Compared with C3 containing bulky dibenzhydryl substituents, the activity of C2 was sensitive to the change of the polymerization pressure. However, the polyethylenes obtained from complex C3 had lower branching density. Meanwhile, the molecular weight could reach 971 kg/mol, which is almost 5 times as much as that of the polyethylene obtained from complex C2.

为提高α-二亚胺催化剂的热稳定性,采用苊醌和4-溴-2,6-二异丙基苯胺反应,引入大位阻基团,设计合成出了一种新型的α-二亚胺配体,并通过一系列手段进行了表征;在一氯二乙基铝助催化作用下催化乙烯聚合,通过改变聚合条件,探究聚合温度、铝镍比等对催化活性的影响,并通过DSC对聚合物进行了表征分析.研究表明:随着温度的升高,催化活性先升高后降低,50℃时最高为4.28×106 g PE/mol Ni·h,80℃仍保持较高的催化活性,对比之前报道,活性中心附近位阻增大能够使热稳定性提高;相同温度下,催化活性有随铝镍比的提高而增加的趋势;聚合物支化度随着聚合温度的提高而增加.

为了提高教学效果,在高分子化学理论教学中,采用实验微课及模拟动画,以"甲基丙烯酸甲酯的本体聚合"实验以及自由基聚合中的链引发和链增长基元反应为例,实验视频或动画的展示与教师对相关知识点的讲解进行有机结合,把枯燥、抽象的理论变得形象生动、直观,学生可以迅速掌握重点,建立概念、稳固知识,学习兴趣大增.

为了提高催化剂的热稳定性,设计合成了一种新型的大骨架结构的 α-二亚胺配体L及其Ni(Ⅱ)配合物Cat,并采用红外(FTIR)、核磁(NMR)、元素分析(EA)等手段对其进行了表征,进而探究了在助催化剂一氯二乙基铝的作用下,聚合温度、压力及铝镍比等因素对催化性能的影响,并采用DSC、GPC、13C NMR分别对聚乙烯产物进行了表征.结果表明:压力的增加将导致聚合活性的增加,在聚合压力为0.5 MPa时,催化剂的活性随着温度先升后降,并在温度为50℃时达到最高值为4.22×106 g/(mol·h).同时,当聚合温度从50℃升高至70℃后,聚乙烯数均分子质量从143 kg/mol降低到125 kg/mol,支化度则从125个支链/1000 C升高到了135个支链/1000 C.

为探究N,N′-二(2,6-二异丙基)苊二亚胺溴化镍配合物无法催化乙烯、降冰片烯共聚的原因,使用Gaussian软件,运用密度泛函数理论(DFT),将乙烯、降冰片烯共聚过程分为3个阶段:单体竞争链引发过程、单体竞争再插入过程、乙烯链增长和β-H转移反应竞争过程,并依序计算每个阶段的动力学能量.结果显示:每个阶段中具有动力学优势的反应分别是降冰片烯单体的链引发、乙烯单体的再插入、链增长过程的β-H转移反应.这3个优势反应将构成"体系循环",使共聚过程仅能获得小分子链段,导致共聚无产物.

MgCl2-supported titanium Ziegler-Natta catalyst containing CO2-based poly(propylene ether carbonate) diols as a potential internal electron donor (IED) was synthesized and employed for 1-butene polymerization. When compared with the Ziegler-Natta catalyst using poly(polypropylene glycol) as IED, the catalyst prepared with poly(propylene ether carbonate) diols showed good particle morphology, higher activity and stereoselectivity. The results suggested that existence of the carbonate group within the structure of poly(propylene ether carbonate) diols truly plays an important role in improving the performance of the catalyst for the 1-butene polymerization.

烯烃配位聚合技术的发展突飞猛进,本文就 《高分子化学》 配位聚合一章节的教学提出一些自己的体会.在配位聚合的教学中,将有机、 无机等知识引入,以及将高分子化学中的其它链锁聚合的内容进行衔接,有助于学生更好学习本章节的内容.对引发剂与催化剂、 引发剂(催化剂)的分类、 立构规整度与结晶度、 配位聚合实施方法等这几个知识点进行补充讲解,加深对教学难点的理解,以便提高教学质量,达到更好的教学效果.

Three cis-5-Norbornene-endo-2,3-dicarboxylic acid esters were synthesized and employed as internal electron donor (IED) of Ziegler-Natta catalysts,and 1-butene polymerizations were performed under these catalysts prepared.It is found that PB obtained by catalyst containing cis-5-norbornene-endo-2,3-dicarboxylic acid dimethyl ester as IED and diisobutyldimethoxysilane as external electron donor,possess the largest Mw (98.1 × 104),the narrowest PDI (5.6),and the highest isotacticity (97.0％),while the activity of catalyst employed cis-5-norbornene-endo-2,3-dicarboxylic acid diethyl ester as IED is much higher compared with others.What is more,the performance of the cis-5-norbornene-endo-2,3-dicarboxylic acid ester-based Ziegler-Natta catalysts is much better in catalyst activity than the Ziegler-Natta catalyst containing cis-bicyclo [2.2.1] hept-endo-2,3-dicarboxylic acid diethyl ester as IED.

The advance of the internal electron donors(IEDs) in Ziegler-Natta catalysts was reviewed and the effects of IEDs on butene-1 polymerization were also discussed.The development of polymerization process for butene-1 polymerization were also introduced,including slurry polymerization,gas phase polymerization and liquid bulk polymerization.And the advantage and/ or disadvantage of these polymerization processes were briefly introduced.Finally,the prospect of polybutene-1 was highlighted.

Two α-diimine nickel complexes with benzophenyl groups at the ortho position of aniline were used in the homopolymerization of norbornene and copolymerization of norbornene with 1-hexene in the presence of methylaluminoxane.The effects of some reaction parameters,such as polymerization temperature,Al/Ti molar ratio and solvent,on homo-polymeration activity were studied.The effects of polymerization temperature and comonomer ratio on copolymerization activity were also discussed.The microstructure,glass transition temperature,relative molecular mass and thermal stability of the resulting polymers were characterized by FTIR,13C NMR,DMA etc.With increasing 1-hexene feed ratios,the catalytic activity and glass transition temperature decreased.However,the 1-hexene content in the copolymers was lower.The two a-diimine nickel complexes demonstrated high thermal stability and high activity in chlorinated solvents.And the homo-and copolymerization of norbomene are vinyl addition polymerizations.