碳笼烯(C60)在高分子领域中的研究进展

综述了碳笼烯（Ｃ６０）在高分子领域中的研究进展,包括碳笼烯的高分子化、与聚合物形成电荷转移复合物以及作为催化聚合反应的催化剂。     

碳笼烯的高分子化──苯乙烯－烯丙基胺共聚物与C_（60）的反应

碳笼烯的高分子化──苯乙烯－烯丙基胺共聚物与Ｃ＿（６０）的反应田慧洁，周锡煌，李福绵（北京大学化学系北京１００８７１）关键词碳笼烯的高分子化，Ｃ＿（６０），苯乙烯－烯两基胺共聚物碳笼烯（ｆｕｌｌｅｒｅｎｅ）是因其具有特殊的功能性质ｍ而颇受青睐的球簇分...     

间规立构聚丙烯的结晶度研究

Ｎａｔａ等用Ｚｉｅｇｌｅｒ－Ｎａｔａ催化剂首次合成了间规度为～５０％间规聚丙烯，并对其进行了表征，指出其具有（ＴＴＧＧ）２螺旋构象，正交晶系，Ｃ２２２１空间群［１，２］．近年来用茂金属催化剂合成的间规立构聚丙烯（ｓＰＰ）的间规度可达９３％以上，高间规...     

丙烯丁烯共聚物的组成和等规度分布

丙烯丁烯共聚物的组成和等规度分布徐君庭封麟先杨士林（浙江大学高分子科学与工程学系杭州３１００２７）关键词丙烯丁烯共聚物，Ｚｉｅｇｌｅｒ Ｎａｔａ催化剂，分级用负载型Ｚｉｅｇｌｅｒ Ｎａｔａ催化剂制备的聚丙烯其等规度往往分布较宽，具有一定的分散性...     

一种提高茂金属载体催化剂催化性能的方法

茂金属配合物（Ｍｃ）是继Ｚｉｅｇｌｅｒ－Ｎａｔａ催化剂之后的最重要的新一代聚烯烃催化剂，尤其是１９８０年Ｋａｍｉｎｓｋｙ催化剂体系Ｃｐ２ＺｒＣｌ２／ＭＡＯ的诞生，是均相聚烯烃发展史上一次大革命。甲基铝氧烷（ＭＡＯ）作为助催化剂的催化剂体系相对于传统催...     

含水溶性碳笼烯的水凝胶

含水溶性碳笼烯的水凝胶陈立桅郑磊洪瀚李子臣周锡煌李福绵（北京大学化学系北京１００８７１）关键词水溶性碳笼烯，水凝胶，超氧负离子随着碳笼烯（Ｃ６０，Ｃ７０，ｆｕｌｅｒｅｎｅｓ）的简便制取方法［１］的问世，其应用，特别是其材料化自然被提到日程上来．...     

球笼烯（C_（60）／C_（70）载体钕系催化丁二烯聚合的研究

球笼烯（Ｃ_（６０）／Ｃ_（７０）载体钕系催化丁二烯聚合的研究赵春英，陈滇宝，仲崇祺，董文寰，徐玲，唐学明（青岛化工学院高分子材料系青岛２６６０４２）杨海滨，李明辉，邹广田（吉林大学超硬材料国家重点实验室长春１３００２３）关键词球碳载体钕系催化剂，聚丁...     

球笼烯（C_（60）／C_（70）载体钕系催化丁二烯聚合的研究

球笼烯（Ｃ_（６０）／Ｃ_（７０）载体钕系催化丁二烯聚合的研究赵春英，陈滇宝，仲崇祺，董文寰，徐玲，唐学明（青岛化工学院高分子材料系青岛２６６０４２）杨海滨，李明辉，邹广田（吉林大学超硬材料国家重点实验室长春１３００２３）关键词球碳载体钕系催化剂，聚丁...     

C60碳笼的化学反应研究进展

综述Ｃ６０碳笼的几种化学反应类型，重点介绍Ｃ６０碳笼的加成反应等的最新进展。     

C_（60）与含烯丙基胺聚合物加成物的荧光行为

Ｃ_（６０）与含烯丙基胺聚合物加成物的荧光行为田慧洁，陈立桅，姚光庆，金朝霞，李福绵（北京大学化学系北京１００８７１）关键词脂肪胺，Ｃ_（６０），聚烯丙基胺，荧光Ｃ６０是一高度对称的笼状碳簇分子，室温下难以观察到荧光现象［１］，但我们发现它与聚烯丙基胺...     

含C_(60)聚乙基乙烯基醚的合成及其荧光行为

Ｃ６０的高分子化一直被认为是Ｃ６０材料化的一个重要途径［１～５］,但含Ｃ６０的高分子的制备及其性能表征却遇到很多困难．迄今为止,制备含Ｃ６０的高分子的方法多采用自由基引发剂或阴离子引发剂引发Ｃ６０与烯类单体共聚［２,３,６］,这使共聚单体的范围受到限...     

Polymerization of ethylene using a high-activity Ziegler–Natta catalyst. II. Molecular weight regulation

This article describes studies on the variables that regulate the molecular weight in ethylene polymerization using a highly active Ziegler–Natta catalyst with hydrogen for molecular weight control. The dependence of the degree of polymerization on the concentration of catalyst, cocatalyst, monomer, partial pressure of hydrogen, and temperature has been established. The rate constant for chain transfer with cocatalyst has been evaluated. © 1993 John Wiley & Sons, Inc.     

Preparation of ultra high molecular weight amorphous poly(1‐hexene) by a Ziegler–Natta catalyst

High molecular weight polymers such as poly (α‐olefin)s play a key role as drag‐reducing agents which are commonly used in pipeline industry. Heterogeneous Ziegler–Natta catalyst system of MgCl₂.nEtOH/TiCl₄/donor was prepared using a spherical MgCl₂ support and utilized in synthesis of poly(1‐hexene)s with a viscosity average molecular weight (M_v) up to 3.5 × 10³ kDa. The influence of effective parameters including Al/Ti ratio, polymerization temperature, monomer concentration, effect of alkylaluminus type on the productivity, and molecular weight of the products was evaluated. It was suggested that the reactivity of the Al‐R group and the bulkiness of the cocatalyst were correlated to the performance of the Ziegler–Natta catalyst at different polymerization time and temperatures, affecting the catalyst activity and M_v of polymers. Moreover, bulk polymerization method leads to higher viscosity average molecular weights, revealing the remarkable effect of polymerization method on the chain microstructure. Fourier transform infrared, ¹³C Nuclear magnetic resonance spectra, and DSC thermogram of the prepared polymers confirmed the formation of poly(1‐hexene). The properties of the polymers measured by vortex test showed that these polymers could be used as a drag‐reducing agent. Drag‐reducing behaviors of the polymers exhibited a dependence on the M_v of the obtained polymers that was changed by variation in polymerization parameters. Copyright © 2016 John Wiley & Sons, Ltd.     

Application of Monte Carlo simulation method to polymerization kinetics over Ziegler–Natta catalysts

In the current work, the Monte Carlo simulation method was applied to ethylene polymerization over Ziegler–Natta catalysts. As expected, polymerization over each center of a Ziegler–Natta catalyst leads to a polymer having a Schultz–Flory molecular weight distribution. Notwithstanding, the total molecular weight distribution obtained by all catalyst centers together is at least twice as broad as that of each center. As another interesting finding, the introduction of hydrogen to the reaction deactivates the catalyst active centers and thereby reduces the catalyst activity. Nevertheless, it does not mainly affect the polymerization kinetics. In addition, the polymer molecular weight falls as hydrogen is added to the reaction since it acts as a strong transfer agent. The same effect is seen when cocatalyst concentration increases. Hydrogen also widens the polymer molecular weight distribution. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 45–56, 2009     

Synthesis of Ultra-High Molecular Weight Polyolefins of Regular Structure in Octafluorobutane Medium

Russian Journal of Applied Chemistry - The suspension polymerization in octafluorobutane, initiated by Ziegler–Natta catalyst system, has been used to synthesize ultra-high molecular weight...     

Effects of external donors and hydrogen concentration on oligomer formation and chain end distribution in propylene polymerization with Ziegler‐Natta catalysts

The effect of type and concentration of external donor and hydrogen concentration on oligomer formation and chain end distribution were studied. Bulk polymerization of propylene was carried out with two different Ziegler‐Natta catalysts at 70 °C, one a novel self‐supported catalyst (A) and the other a conventional MgCl₂‐supported catalyst (B) with triethyl aluminum as cocatalyst. The external donors used were dicyclopentyl dimethoxy silane (DCP) and cyclohexylmethyl dimethoxy silane (CHM). The oligomer amount was shown to be strongly dependent on the molecular weight of the polymer. Catalyst A gave approximately 50 % lower oligomer content than catalyst B due to narrower molecular weight distribution in case of catalyst A. More n‐Bu‐terminated chain ends were found for catalyst A indicating more frequent 2,1 insertions. Catalyst A also gave more vinylidene‐terminated oligomers, suggesting that chain transfer to monomer, responsible for the vinylidene chain ends, was a more important chain termination mechanism for this catalyst, especially at low hydrogen concentration. Low site selectivity, due to low external donor concentration or use of a weak external donor (CHM), was also found to increase formation of vinylidene‐terminated oligomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 351–358, 2010     

Hydrogen effects in propylene polymerization reactions with titanium‐based Ziegler–Natta catalysts. II. Mechanism of the chain‐transfer reaction

Hydrogen is a very effective chain‐transfer agent in propylene polymerization reactions with Ti‐based Ziegler–Natta catalysts. However, measurements of the hydrogen concentration effect on the molecular weight of polypropylene prepared with a supported TiCl₄/dibutyl phthalate/MgCl₂ catalyst show a peculiar effect: hydrogen efficiency in the chain transfer significantly decreases with concentration, and at very high concentrations, hydrogen no longer affects the molecular weight of polypropylene. A detailed analysis of kinetic features of chain‐transfer reactions for different types of active centers in the catalyst suggests that chain transfer with hydrogen is not merely the hydrogenolysis reaction of the Ti? C bond in an active center but proceeds with the participation of a coordinated propylene molecule. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1899–1911, 2002     

Homopolymerization and copolymerization of vinyl chloride over supported metalorganic catalysts

The homopolymerization of vinyl chloride and its copolymerization with ethylene over dibutyl ether–modified SiO₂-supported Ziegler–Natta catalysts based on titanium and vanadium chlorides have been studied. The supported metal complexes are sufficiently active in the polymerization of vinyl chloride. Their activity depends on the catalyst composition and conditions of formation of the catalyst on the surface of the support. The chain structure of the resulting polyvinyl chloride (PVC) has been studied by NMR spectroscopy. The thermal properties of the synthesized PVC have been investigated by differential scanning calorimetry. The PVC obtained possesses enhanced thermal stability owing to the specific features of its chain structure. Vinyl chloride polymerization over the supported metalorganic catalyst proceeds mainly via a free-radical mechanism. Process conditions have been found for conducting the copolymerization of vinyl chloride with ethylene over supported metal complexes resulting in the formation of true statistical copolymers, which is confirmed by IR and NMR spectroscopy.     

Copolymerization of 1‐hexene and ethylene catalyzed by the Ziegler catalyst Cp*TiMe3/B(C6F5)3

The Ziegler–Natta system Cp*TiMe₃/B(C₆F₅)₃ catalyzed the copolymerization of ethylene and 1‐hexene in toluene into materials that were characterized by ¹H and ¹³C{¹H} NMR spectroscopy, differential scanning calorimetry, and gel permeation chromatography. The effects of temperature and ethylene/1‐hexene and olefin/catalyst ratios on catalyst activities and copolymer molecular weights and molecular weight distributions were studied; the ethylene proportions varied from less than 5% to 85% or more. In addition, significant amounts of 1‐hexene were incorporated into the growing polymer chain in a 2,1‐fashion; consequently, conventional ¹³C NMR analytical methodologies for deducing monomer proportions and dispersions and polymer microstructures, based on a low 1,2‐incorporation of α‐olefin, did not work very well. A soluble (in toluene at ambient temperature) but very high molecular weight (weight‐average molecular weight ∼ 8 × 10⁵, weight‐average molecular weight/number‐average molecular weight = 1.8) rubbery copolymer that formed at −78 °C exhibited a predominantly alternating microstructure. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3966–3976, 2000     

Criteria for diffusion limitation in coordination polymerization

The following criteria are proposed to judge whether a coordination polymerization may be diffusion controlled or not: (1) If the number-average molecular weight and polydispersity of the polymer calculated from kinetic rate constants as a function of time agree with the experimental values, the polymerization is not diffusion controlled. (2) The polymerization may be diffusion controlled if the Thiele modulus, the ratio of the characteristic diffusion time to the characteristic reaction time, is much greater than unity; if it is much smaller than unity, the polymerization is reaction controlled. (3) If an initial linear dependence of rate of polymerization on catalyst concentration changes over to a square-root dependence, the polymerization may be diffusion limited. (4) The polymerization is likely to be diffusion limited if the instantaneous rate of polymerization is proportional to the rate of particle growth when the proportionality coefficient is the surface area of the particle. Criterion (1) is a necessary and sufficient condition as stated, as its converse is not true. All the other criteria are merely necessary but not sufficient conditions. The established Ziegler–Natta catalysts have activities too low to cause diffusion limitation; the Phillips catalyst system is likely to be diffusion limited. The polydispersity of polyolefins produced with Ziegler–Natta catalysts are not the consequence of diffusion control but are the characteristics of the catalysts in their kinetics of initiation, propagation, chain transfer, and termination.