Effect of cocatalysts on ethylene polymerization with fluorinated bisphenoxyimine titanium as a catalyst

In this study, we examined various alkylaluminums, including triethylaluminum (TEA), triisobutylaluminum (TIBA), and diethylaluminum chloride (DEAC), as cocatalysts for the activation of ethylene polymerizations in the presence of a fluorinated Fujita group invented titanium (FI‐Ti) catalyst, bis[N‐(3‐tert‐butylsalicylidene)‐2,3,4,5,6‐pentafluoroanilinato] titanium(IV) dichloride (complex 1 ). DEAC, because of the strong Lewis acidity, was an efficient cocatalyst for activating complex 1 for the ethylene polymerizations, whereas TEA and TIBA as cocatalysts could hardly polymerize ethylene. The effects of the polymerization temperature and Al/Ti molar ratio on the formation of active species, properties, and molecular weight of the resulting polyethylene were investigated. In the complex 1 /DEAC catalyst system, the oxidation states of Ti active species were determined by electron paramagnetic resonance. The results demonstrated that Ti(IV) active species were inclined to polymerize ethylene and yielded high‐molecular‐weight polyethylene. Comparatively, Ti(III) active species resulted from the reduction of Ti(IV) by DEAC and afforded oligomers. Moreover, the bigger steric bulk for the cocatalysts was necessary to achieve ethylene living polymerization with the fluorinated FI‐Ti catalyst. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Living/controlled hex-1-ene polymerization initiated by nickel diimine complexes activated by non-MAO cocatalysts: Kinetic and UV-vis study

Living/controlled polymerization of hex-1-ene initiated by nickel diimine catalysts of general form [ArN=C(1,8-naphthalenediyl)C=NAr]NiBr₂ activated by simple organoaluminium compounds was investigated. Polyhexenes with a very narrow molar mass distribution and molar mass controlled by the monomer/initiator ratio were prepared using diethylaluminiumchloride, ethylaluminiumdichloride and methylaluminiumdichloride as cocatalysts for nickel complexes 1 (Ar = 2,6-iPr₂C₆H₃) and 2 (Ar = 2-tBuC₆H₄). Nickel complexes with smaller aryl substituents (3, Ar = 2,6-Me₂C₆H₃; 4 Ar = 2,4,6-Me₃C₆H₂; 5, Ar = 2,6-Et₂C₆H₃) undergo transfer reactions significantly. For the most bulky complex 1 activated by ethylaluminiumdichloride living hex-1-ene polymerization was achieved, proved by the reinitiation of polymer growth upon the addition of fresh monomer. The effect of Al/Ni ratio on the activity of the catalytic systems was studied by dilatometry. The catalytic systems were investigated by UV-vis spectrometry and a new interpretation of their absorption spectra was suggested.     

Synthesis of cationic nickel(II) compounds for butadiene polymerization

A series of cationic nickel(II) compounds with various counter ions ([BF₄]^–, [CF₃SO₃]^–) and N‐bearing ligands (1,10‐phenanthroline, benzimidazole and terpyridine) were synthesized. The simple compound, Ni(Phen)₂Cl₂, was prepared as a reference compound. All title compounds were characterized by elemental analysis, and infrared spectra analyses and compounds, some specific ones, were further examined by X‐ray crystallographic analysis. Upon treatment with ethylaluminum sesquichloride, these nickel(II) compounds exhibited high activities (up to 88.5%/4 h) for butadiene polymerization and afforded liquid polybutadiene (M_w < 30,000) with a high cis‐content (up to 92.1%). Various polymerization conditions were investigated in detail, and it was found that less steric hindrance of the ligands enhanced the catalytic activities of the nickel(II) compounds. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40511.     

The influence of cocatalysts on 1-hexene polymerization with various supported magnesium – titanium catalysts

Summary The influence of various cocatalysts on the activity and stereospecificity of a supported magnesium–titanium catalyst, generated by in situ reduction of titanium (IV) chloride using a Grignard reagent (MgCl₂/TiCl₃) or prepared by the recrystallization method (MgCl₂/2M2P/ED/TiCl₄, 2M2P= 2-methyl-2-pentanol, ED= dibutyl phthalate or ethyl benzoate), in the 1-hexene polymerization was investigated. The MgCl₂/TiCl₃ catalyst showed the highest activity but the lowest stereospecificity in the 1-hexene polymerization with all investigated cocatalysts. The MgCl₂/2M2P/ED/TiCl₄ catalyst with dibutyl phthalate as an internal electron donor was characterized by the highest stereospecificity and led to the polymers with high molecular weight. All catalysts showed the highest activity and stereospecificity when triisobutylaluminium was used as a cocatalyst. The addition of a small amount of ethyl benzoate as an external electron donor ([Al]/[ED] 10:1) led to considerable improvement of the stereospecificity of the MgCl₂/TiCl₃ catalyst in comparison with the catalysts prepared by the recrystallization method.     

Butadiene polymerization with a rare earth compound using a magnesium alkyl cocatalyst: 2

A catalyst was developed for the preparation of high cis polybutadiene consisting of ‘didymium’ versatate — aluminium alkyl halide — magnesium dialkyl. By altering the order of component addition and using neodymium versatate, the catalyst activity and cis content of the polymer were both increased. The aluminium alkyl halide could be replaced by mixtures of aluminium trialkyl plus silicon halides or organic halides. Various additives were tried in order to reduce polymer molecular weight and to alter the molecular weight distribution.     

Butadiene polymerization with a rare earth compound using a magnesium alkyl cocatalyst: 1

High trans polybutadiene was obtained using a catalyst system comprising rare earth compounds plus magnesium dialkyl. The polymer appeared to contain some ‘live’ chain ends and block polymerization and coupling experiments were carried out. High cis polybutadienes formed when aluminium alkyl halides were used as a third catalyst component.     

ZnR2对镍催化体系合成高顺式聚丁二烯的影响

采用新的镍催化体系Ni(naph)2-Al(i-Bu)3-ZnR2-BF3OEt2合成高顺式聚丁二烯，系统地研究了ZnR2的加入对聚合反应及其产物的影响。考查了聚合反应动力学，并对聚合产物进行了测试和表征。实验结果表明：在Ni-Al-B催化体系中加入ZnR2后，丁二烯的聚合反应速率略有降低，分子量分布逐渐变窄，顺1，4式的质量分数保持在96％以上，凝胶含量显著降低。     

丁二烯本体聚合及与异戊二烯的共聚合

研究了负载钛催化剂引发丁二烯本体聚合合成高反式-1,4-聚丁二烯的条件,如催化剂组成、温度、时间、催化剂用量等对聚合过程和催化效率的影响.在Al/Ti摩尔比为70,30℃,8h条件下,在Ti/Bd(摩尔比)为(1～2)×10-5时,丁二烯的本体聚合具有最佳催化效率,聚丁二烯的反式-1,4-结构摩尔分数为99%.并对丁二烯和异戊二烯的共聚合进行了研究,结果表明二者发生了共聚合.     

Butadiene polymerization with vanadium–titanium–aluminum catalytic systems

Butadiene polymerization in the presence of mixed vanadium–titanium–aluminum catalytic systems containing various organoaluminum compounds (OACs) was investigated. The main factors influencing the activity and stereospecificity of the [VOCl₃–TiCl₄–OAC₁]–(heating)–OAC₂ catalysts [where OAC₁ and OAC₂ were Al(i‐Bu)₃, Al(i‐Bu)₂H, or Al(i‐Bu)₂Cl] were considered. The kinetic parameters of the process were determined. The high activity and stereospecificity of the multicomponent systems probably accounted for the formation of polymerization active sites with both transition‐metal derivatives in their structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 211–217, 2004     

Microgels as new support materials for heterogeneous cocatalysts in ethylene polymerization reactions

Microgels are monodisperse poly(organosiloxane) microparticles that can be functionalized at their surface. These materials were tested as supports for heterogeneous cocatalysts of the methylaluminoxane type and were used for the polymerizations of olefins with transition‐metal catalysts. The cocatalysts were synthesized directly on the surfaces of the microgel particles by the partial hydrolysis of trimethylaluminum and were then used for the activation of homogeneous catalyst precursors. Complexes of various chemical natures were successfully activated and optimized through variations in the Al/H₂O ratio used for the synthesis. Metallocene dichloride complexes and coordination compounds of iron and nickel were tested as catalysts for ethylene polymerization, and the results were compared with the results for the homogeneous systems and heterogeneous systems supported on silica gel (SiO₂). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3021–3029, 2002     

Effect of reaction parameters on the polymerization of methyl methacrylate with nickel acetylacetonate/methylaluminoane

Polymerizations of methyl methacrylate (MMA) employing nickel acetylacetonate [Ni(acac)₂] as catalyst combined with methylaluminoxane (MAO) as cocatalyst were investigated. The main purpose of this work is concerned with the study of reaction parameters MMA polymerization. Temperature of polymerization, Al/Ni mole ratio, type of solvent, catalyst concentration and time dependence were examined. The influence of Lewis bases on the polymerization was also studied. The binary system Ni(acac)₂/MAO was the only one able to polymerize MMA at the conditions employed in this work. The cocatalytic activity of MAO was compared to those of common alkylaluminium compounds. The polymers were characterized by gel-permeation chromatography (GPC) and ¹³C-NMR techniques. Received: 20 August 1996/Revised: 4 December 1996/Accepted: 9 December 1996     

聚合条件对镍系催化聚丁二烯影响的研究

采用Al—M陈化，稀B和醇以及稀B和H2O单加的方式合成顺丁橡胶。通过H2O／油在超声波中的振荡，使H2O均匀地分散在汽油中并充分与B反应；通过H2O／B在超声波中的振荡，改善B在汽油中的分散。对ROH／B和H2O／B体系，研究了催化剂配比、聚合温度、反应时间对单体转化率、相对分子质量及微观结构的影响，适当的Al／B和H2O／B比可以提高聚合体系的反应活性。     

磷酸酯配体对镍系催化剂催化丁二烯聚合的影响

研究了在环烷酸镍-三异丁基铝(简称Al)-三氟化硼乙醚络合物(简称B)体系中添加磷酸二(2-乙基己基)酯(简称P)对丁二烯聚合活性的影响,并通过傅里叶变换红外光谱、凝胶渗透色谱、凝胶渗透色谱-激光光散射仪-黏度计在线联用系统等对聚合物结构进行了表征。结果表明,采用P-B预混的陈化方式,取P与B的摩尔比为0.020,在Al与B的摩尔比为0.7~2.0时单体转化率都达了90%以上。聚合物的相对分子质量可通过改变P/B或Al/B进行调节。P的引入对聚合产物的顺式结构含量几乎没有影响,产物仍为高顺式聚丁二烯;在高相对分子质量级分的支化度较高,所得聚合物溶液的剪切黏度下降。     

High molecular weight poly(l-lactide) via ring-opening polymerization with bismuth subsalicylate–The role of cocatalysts

The catalytic potential of bismuth subsalicylate (BiSub), a commercial drug, for ring-opening polymerization of l -lactide was explored by variation of cocatalyst and polymerization time. Various monofunctional phenols or carboxylic acids, aromatic ortho-hydroxy acids, and diphenols were examined as potential cocatalysts. 2,2′-Dihydroxybiphenyl proved to be the most successful cocatalyst yielding weight average molecular weights (uncorrected M_w values up to 185,000) after optimization of reaction time and temperature. Prolonged heating (>1-2 h) depending on catalyst concentration) caused thermal degradation. In polymerization experiments with various commercial Bi(III) salts a better alternative to BiSub was not found. By means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry a couple of unusual and unexpected transesterification reactions were discovered. Finally, the effectiveness of several antioxidants and potential catalyst poisons was explored, and triphenylphosphine was found to be an effective catalyst poison.     

High activity mixed metal alkyl cocatalysts for α-olefin polymerization

High activity α-olefin polymerization catalysts are generally obtained by mixing MgCl₂-supported TiCl₄ (MgCl₂/TiCl₄) with an aluminum trialkyl cocatalyst. Surprisingly, AlEt₂Cl, which is the preferred cocatalyst in polymerizations employing nonsupported Ti compounds, is a poor cocatalyst when used with MgCl₂/TiCl₄. It was found that in propylene and 1-butene polymerizations, using different MgCl₂/TiCl₄ catalysts, the cocatalyst activity of AlEt₂Cl can be greatly improved by the addition of a magnesium or lithium alkyl. The mixed metal alkyl obtained from AlEt₂Cl and MgBu₂ is a particularly effective cocatalyst always yielding more polymer, of about the same stereospecificity, than the conventional aluminum trialkyls. The exact nature of the mixed metal alkyl cocatalysts is not known, but the available evidence argues against in situ aluminum trialkyl formation resulting from the alkylation of AlEt₂Cl by the second metal alkyl.     

Role of chiral amine cocatalysts in the helix-sense-selective polymerization of a phenylacetylene using a catalytic system

We have examined the role of the chiral amine cocatalyst in the recently discovered helix-sense-selective polymerization of a phenylacetylene using a catalytic system consisting of an achiral rhodium complex ([Rh(norbornadiene)Cl]₂) as the catalyst and a chiral amine as the cocatalyst. Several chiral amines were effective for the polymerization reaction and their effectiveness depended on their bulkiness and coordination ability to rhodium. The sense selectivity of the polymerization increased with the concentration of the chiral amines. To discuss the structure of the true active species in the catalytic system, we have synthesized a new chiral rhodium complex having two chiral amines as ligands ([Rh(norbornadiene)(chiral amine)₂]⁺BF₄⁻). The isolated chiral complex also catalyzed the helix-sense-selective polymerization. These findings suggest that a chiral rhodium complex having two chiral amines may be the true active species when using the catalytic system consisting of [Rh(norbornadiene)Cl]₂ and a chiral amine.     

Plasma polymerization of organosilicon compounds

Plasma polymerizations in five silicon compounds having chemical formula of (CH₃)₃Si? X? Si(CH₃)₃, X = none, CH₂, NH, O, and S atoms, were investigated by elemental analysis, infrared spectroscopy, and ESCA. The chemical composition of polymers plasma-polymerized was influenced by the X groups in (CH₃)₃Si? X? Si(CH₃)₃. Polymers, when X was S atoms, possessed no sulfur; and X was CH₂ groups polymers rich in carbon and hydrogen atoms were formed. Details in chemical composition were discussed by IR and ESCA. Such differences in chemical composition reflected on gas permeability of the plasma films.     

Hydroboration polymerization of dicyano compounds

Summary Hydroboration polymerization of various ,-dicyanoalkanes with thexylborane produced the corresponding poly(cyclodiborazane)s, that consist of boron-nitrogen four-membered rings. The structures of the obtained polymers were confirmed by spectroscopic analyses such as ¹H-, ¹¹B-NMR and IR spectra. From the result of thermogravimetric analysis of the polymer prepared from adiponitrile and thexylborane, 12% of the inorganic materials remained after heating at 900°C. *** DIRECT SUPPORT *** AEB03051 00003     

Isospecific polymerization of styrene with supported nickel acetylacetonate/methylaluminoxane catalysts

Summary The polymerization of styrene with catalysts based on Ni(acac)₂ supported on SiO₂ and Al₂O₃ was investigated. Using catalysts based on MAO supported on silica, a highly isotactic polystyrene was obtained. Nevertheless, the Al₂O₃-supported catalyst can promote isospecific polymerization activated by common. alkyl aluminum compounds even by any prior support treatment with MAO. Received: 3 March 1998/Revised version: 14 April 1998/Accepted: 14 April 1998