Homo-and copolymerization of propylene and ethylene in the presence of titanium dichloride complexes with dioxolane dicarboxylate and bis(difurylmethanephenoxyimine) ligands

The polymerization of propylene and ethylene and the copolymerization of these olefins with postmetallocene catalysts [(4R,5R)-2,2-dimethyl-α,α,α′,α′-tetra(perfluorophenyl)-1,3-dioxolane-4,5-dimethanol] titanium(IV) dichloride and bis{N-(3,5-ditert-butylsalicylidene)-4-[bis(5-methyl-2-furyl)methyl]aniline}titanium( IV) dichloride have been studied. The polymerization of propylene and its copolymerization with ethylene have been carried out in a liquid monomer, while the polymerization of ethylene has been performed in toluene at the constant concentration of the monomer. Polymethylaluminoxane has been used as a cocatalyst. The activity of the catalysts in the polymerization of propylene and ethylene at 50°C is ～ 10 and ～45 kg PP/mol Ti h mol C₃H₆/l and 178.5 and 2700 kg PE/mol Ti h mol C₂H₄/l, respectively. It has been established that, in the copolymerization of propylene with ethylene, the active sites of both catalysts selectively polymerize ethylene. The resulting copolymers have a block structure (r ₁ r ₂= 4.6); as a result, the crystalline phase of polyethylene is formed in them. Polypropylene and propylene-ethylene copolymers are elastomeric materials. Polypropylene samples synthesized with [(4R,5R)-2,2-dimethyl-α,α,α′,α′-tetra(perfluorophenyl)-1,3-dioxolane-4,5-dimethanol]titanium(IV) dichloride demonstrate a high melting point (150–157°C) in combination with good elastic properties. Polyethylene is a linear polymer with the degree of crystallinity varying from 37 to 45% and a melting point of 133–134°C. The mechanical properties of the polymers and copolymers have been investigated.     

Copolymerization of propylene with various higher α‐olefins using silica‐supported rac‐Me2Si(Ind)2ZrCl2

The copolymerization of propylene with 1‐hexene, 1‐octene, 1‐decene, and 1‐dodecene was carried out with silica‐supported rac‐Me₂Si(Ind)₂ZrCl₂ as a catalyst. The copolymerization activities of the homogeneous and supported catalysts and the microstructures of the resulting copolymers were compared. The activity of the supported catalyst was only one‐half to one‐eighth of that of the homogeneous catalyst, depending on the comonomer type. The supported catalyst copolymerized more comonomer into the polymer chain than the homogeneous catalyst at the same monomer feed ratio. Data of reactivity ratios showed that the depression in the activity of propylene instead of an enhancement in the activity of olefinic comonomer was responsible for this phenomenon. We also found that copolymerization with α‐olefins and supporting the metallocene on a carrier improved the stereoregularity and regioregularity of the copolymers. The melting temperature of all the copolymers decreased linearly with growing comonomer content, regardless of the comonomer type and catalyst system. Low mobility of the propagation chain in the supported catalyst was suggested as the reason for the different polymerization behaviors of the supported catalyst with the homogeneous system. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3294–3303, 2001     

Copolymerization of propylene with 1-octene initiated by highly efficient isospecific metallocene catalytic systems

The copolymerization of propylene with 1-octene in liquid propylene is carried out in the presence of a highly active homogeneous ansa-m etallocene catalyst with the C ₂-symmetry rac-Me₂Si(4-Ph-2- MeInd)₂ZrCl₂ activated by methyl aluminoxane and in the presence of ansa- metallocene C₄H₆Si(2-Et4- PhInd)₂ZrCl₂ (rac: meso = 2:1) supported on silica gel treated with methylaluminoxane. In the case of the heterogenized metallocene, (iso-C ₄ H ₉ )₃Al is used as a cocatalyst. The copolymers of propylene and 1-octene containing up to 24 and 9.3 mol% units of the second comonomer are prepared with the homogeneous and heterogenized systems, respectively. The copolymerization of propylene with 1-octene in liquid propylene shows the azeotropic (ideal) character, and the distribution of comonomer units in the copolymers is close to statistical. The modification of PP with even small amounts of 1-octene affects the regularity of polymer chains, molecular-mass characteristics of the copolymers, their melting temperature, and the degree of crystallinity and makes it possible to vary their rigidity and elasticity in a wide range. The character of changes in thermal and mechanical properties is almost the same for the copolymers synthesized with homogeneous and heterogenized catalysts.     

Copolymerization of propylene with 1-butene and 1-pentene with the isospecific catalytic system rac-Me2Si(4-Ph-2-MeInd)2ZrCl2-MAO

The copolymerization of propylene with 1-butene and 1-pentene at 60°C in the propylene bulk in the presence of the homogeneous isospecific metallocene catalyst of the C₂ symmetry rac-Me₂Si(4-Ph-2-MeInd)₂ZrCl₂ activated by polymethylaluminoxane is studied. Copolymers containing up to 30 mol % 1-butene and up to 10 mol % 1-pentene are synthesized. For the copolymerization of the above monomers, reactivity ratios are estimated to be equal to unity, thereby indicating the azeotropic character of the process. It is found that the distribution of comonomer units in the copolymers is close to statistical. For both comonomers, the comonomer effect is observed: an increase in the rate of propylene polymerization after addition of a small amount of a less reactive comonomer. The addition of 1-butene and 1-pentene to polypropylene shows a weak effect on the stereoregularity of chains but causes a marked reduction in the molecular mass of the polymer and changes its thermophysical characteristics and mechanical properties. An X-ray diffraction study of the copolymers is performed.     

Shape and diffusion of the monomer‐controlled copolymerization of ethylene and α‐olefins over Cp2ZrCl2 confined in the nanospace of the supercage of NaY

Cp₂ZrCl₂ confined inside the supercage of NaY zeolites [NaY/methylaluminoxane (MAO)/Cp₂ZrCl₂] exhibited the shape and diffusion of a monomer‐controlled copolymerization mechanism that strongly depended on the molecular structure of the monomer and its size. For the ethylene–propylene copolymerization, NaY/MAO/Cp₂ZrCl₂ showed the effect of the comonomer on the increase in the polymerization rate in the presence of propylene, whereas the ethylene/1‐hexene copolymerization showed little comonomer effect, and the ethylene/1‐octene copolymerization instead showed a comonomer depression effect on the polymerization rate. Isobutylene, having a larger kinetic diameter, had little influence on the copolymerization behaviors with NaY/MAO/Cp₂ZrCl₂ for the ethylene–isobutylene copolymerization, which showed evidence of the shape and diffusion of a monomer‐controlled mechanism. The content of the comonomer in the copolymer chain prepared with NaY/MAO/Cp₂ZrCl₂ decreased by about one‐half in comparison with that of Cp₂ZrCl₂. A differential scanning calorimetry study on the melting endotherms after the successive annealing of the copolymers showed that the copolymers of NaY/MAO/Cp₂ZrCl₂ had narrow comonomer distributions, whereas those of homogeneous Cp₂ZrCl₂ were broad. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2171–2179, 2003     

Alternating copolymer of butadiene and propylene. III

Alternating copolymerizations of butadiene with propylene and other olefins were investigated by using VO(acac)₂–Et₃Al–Et₂AlCl system as catalyst. Butadiene–propylene copolymer with high degree of alternation was prepared with a monomer feed ratio (propylene/butadiene) of 4. Alternating copolymers of butadiene and other terminal olefins such as butene-1, pentene-1, dodecene-1, and octadiene-1,7 were also obtained. However, the butadiene–butene-2 copolymerization did not yield an alternating copolymer but a trans-1,4-polybutadiene.     

Synthesis and properties of polyethylene with side‐chain triphenylamines as hole‐transporting materials

The copolymerization of ethylene with triphenylamine (TPA)‐containing α‐olefin monomer 1 using a rac‐Et(Ind)₂ZrCl₂ ( EBIZr )/MAO catalytic system was investigated to prepare polyethylene with pendent TPA groups. Despite the presence of a large excess of TPA moieties, the polymerization reactions efficiently produce copolymers of high‐molecular‐weight with the comonomer incorporation up to 6.1 mol % upon varying the comonomer concentration in the feed. Inspection of the aliphatic region of the ¹³C‐NMR spectrum and the estimated copolymerization parameters (r ₁ ≈ 0 for 1 and r_E ≈ 43 for ethylene) reveal the presence of isolated comonomer units in the polymer chain. While UV–vis absorption measurements of the copolymers show an invariant absorption feature, PL spectra exhibit a slightly red‐shifted emission with increasing content of 1 in the polymer chain. All the copolymers show high thermal stability (T_d5 > 436 °C), and the electrochemical stability toward oxidation is also observed. Particularly, the copolymer displays hole‐transporting ability for the stable green emission of Alq₃ when incorporated into the hole‐transporting layer of an electroluminescence device. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5816–5825, 2008     

Copolymerization of ethylene and propylene catalyzed by magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts

Magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts with di-i-butyl phthalate as internal donor for copolymerization of ethylene and propylene were prepared.The effects of reaction temperature, ethylene/propylene molar ratio,aluminium/vanadium（Al/V）molar ratio and titanium/vanadium molar ratio on the catalytic activity were investigated.The molecular weight,molecular weight distribution,sequence composition and crystallinity of the products were measured by gel permeation chromatography,¹³C-NMR and differential scanning calorimetry analysis, respectively.In comparison to the vanadium and titanium catalysts,the bimetallic catalyst showed higher catalytic activity and better copolymerization performance.The obtained ethylene/propylene copolymers have high molecular weight （10⁵）,broad molecular weight distribution,high propylene content with random or short blocked sequence structures （r_Er_P=1.919）,low melting temperatures and low crystallinities（X_c<20%）.     

Homo-and copolymerization of vinylcyclohexane with α-olefins in the presence of heterogeneous and homogeneous catalytic systems

The polymerization and copolymerization of vinylcyclohexane with α-olefins in the presence of several heterogeneous and homogeneous catalytic systems were studied. It was shown that, with respect to activity in the polymerization of vinylcyclohexane, the tested catalysts can be arranged in the following order: α-TiCl₃ < titanium-magnesium catalyst < metallocene catalyst. Poly(vinylcyclohexane) prepared with heterogeneous catalytic systems is a solid semicrystalline polymer. The properties of polymers synthesized with homogeneous systems differ substantially depending on the type of the metallocene used. In the presence of metallocenes with a C ₂ symmetry, crystalline powderlike products arise, while in the case of metallocenes with C ₁ and C _s symmetries, polymerization yields amorphous viscous products. Molecular-mass distributions of poly(vinylcyclohexane) samples prepared using both heterogeneous titanium-magnesium catalysts and homogeneous metallocene complexes show a bimodal pattern, indicating the heterogeneity of active centers of these catalysts. Upon introduction of a comonomer (ethylene, propylene, and 1-hexene) into the reaction mixture, the activity of all studied catalytic systems increases. When Me₂C(3-Me-Cp)(Flu)ZrCl₂ and rac-Me₂SiInd₂ZrCl₂ are used as catalysts, the degree of crystallinity of the copolymers grows owing to the presence of ethylene or propylene units in poly(vinylcyclohexane) chains.     

A novel efficient Ti(O-<Emphasis Type="Italic">iso</Emphasis>-C<Subscript>3</Subscript>H<Subscript>7</Subscript>)<Subscript>4</Subscript>-based olefin polymerization catalyst system

The polymerization of ethylene and propylene and the copolymerization of ethylene and hexene-1 with a Ti(O-iso-Pr)₄–AlR₂Cl/MgBu₂ catalyst system have been studied. The advantages of this system over metallocene and postmetallocene catalysts are high activity, low cost, and ease of synthesis. The resulting polymers and copolymers are characterized by a broad molecular-mass distribution, which reflects the heterogeneity of the active sites with respect to kinetic parameters. As a consequence, the ethylene/hexene-1 copolymers exhibit compositional heterogeneity. The active sites of the system produce copolymers with a pronounced tendency toward alternation of monomer units. The propylene polymerization product is mostly amorphous atactic polypropylene.     

Copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with ethylene glycol vinyl ether in aqueous medium

The radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride (AMAC) (M₁) with ethylene glycol vinyl ether (M₂) in an aqueous medium proceeds at a high rate to afford random copolymers. The reactivity ratios equal to r ₁ = 2.18 and r ₂ = 0.01 indicate that AMAC is a more active comonomer. The overall reaction order in comonomers is 2.4, and the effective activation energy is 97.4 ± 2 kJ/mol. The monomer M₁ enters into copolymerization by both of the double bonds with the formation of pyrrolidinium structures in the chain through the cyclization stage.     

Co‐ and terpolymerization of ethylene,propylene, and higher α‐olefins with high propylene contents using metallocene catalysts

The copolymerization of propylene/ethylene and terpolymerization of propylene/ethylene/α‐olefins using long‐chain α‐olefins such as 1‐octene and 1‐decene have been carried out using EtInd₂ZrCl₂//methylaluminoxane. High concentrations of propylene and low concentrations of α‐olefins (near 2 mol % of the total olefin concentration in the liquid phase) were used. The effect of the ethylene concentration in copolymerizations of propylene/α‐olefins was studied at medium ethylene contents (12 and 40 mol % in the gas phase). The polymers were molecularly characterized by gel permeation chromatography‐multiangle laser light scattering, wide‐angle X‐ray scattering, Fourier transform infrared spectroscopy, and DSC analyses. The shorter α‐olefin studied (1‐octene) produced the highest improvement of activity in terpolymerization at 12 mol % ethylene in the gas phase. About 2 mol % of 1‐octene in the liquid phase increases the activity and decreases the molecular weight of terpolymers with respect to corresponding copolymers, whereas the mp is increased by almost 30 °C. The “termonomer effect” is less evident when higher amounts of ethylene are used. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1136–1148, 2001     

Selective dimerization,oligomerization, homopolymerization and copolymerization of olefins with complex organometallic catalysts

Review embarrasses the problems of low molecular weight olefins (ethylene and propylene) selective oligomerization to butene-1, hexene-1, octene-1, 4-methylpentene-1; selective polymerization of olefins to obtain polymers with a given molecular mass, molecular mass distribution, branching (for the polyethylene), chain structure [atactic, iso-, syndio-, gemiisotactic, stereoblock type and containing terminal vinyl and vinylidene bonds (for polypropylene)]; “live” homo-and copolymerization of olefins, and alternating copolymerization of olefins in the presence of complex organometallic catalysts.     

Radiation-induced copolymerization of methyl trifluoroacrylate with propylene

Copolymerization of methyl trifluoroacrylate (MTFA) with propylene in bulk was induced by γ irradiation. A wide range of the initial monomer composition gives an equimolar alternating co-polymer. The reactivity ratios of r₁ (MTFA) and r₂ (propylene) were determined to be 0.01 and 0.005, respectively. The polymerization rate at an equimolar monomer composition is proportional to the 1.0 power of the dose rate. The dose rate dependency of higher than 0.5 may be ascribed to unimolecular termination due to a degradative chain transfer of propagating radicals to propylene. The G values of the initiating radical formation and the polymerization reaction were calculated to be 1.78 and 1336, respectively. The dependence of the copolymerization rate on the temperature was small, and the activation energy of copolymerization was 1.1 kcal/mole from ?6 to 50°C.     

Substituent effect of bisindenyl zirconene catalyst on ethylene/1-hexene copolymerization and propylene polymerization

Nonbridged bis-substituted indenyl zirconene complexes were used as the catalysts for ethylene/1-hexene copolymerization and propylene polymerization. The complicated “comonomer effect” on the activity of ethylene/1-hexene copolymerization was observed. The effect also worked on the incorporation of comonomer. The number and the position of the substituents were important for the copolymerization behavior and the microstructure of the resultant copolymer as well as for propylene polymerization.     

Multicenter nature of titanium‐based Ziegler–Natta catalysts: Comparison of ethylene and propylene polymerization reactions

This article discusses the similarities and differences between active centers in propylene and ethylene polymerization reactions over the same Ti‐based catalysts. These correlations were examined by comparing the polymerization kinetics of both monomers over two different Ti‐based catalyst systems, δ‐TiCl₃‐AlEt₃ and TiCl₄/DBP/MgCl₂‐AlEt₃/PhSi(OEt)₃, by comparing the molecular weight distributions of respective polymers, in consecutive ethylene/propylene and propylene/ethylene homopolymerization reactions, and by examining the IR spectra of “impact‐resistant” polypropylene (a mixture of isotactic polypropylene and an ethylene/propylene copolymer). The results of these experiments indicated that Ti‐based catalysts contain two families of active centers. The centers of the first family, which are relatively unstable kinetically, are capable of polymerizing and copolymerizing all olefins. This family includes from four to six populations of centers that differ in their stereospecificity, average molecular weights of polymer molecules they produce, and in the values of reactivity ratios in olefin copolymerization reactions. The centers of the second family (two populations of centers) efficiently polymerize only ethylene. They do not homopolymerize α‐olefins and, if used in ethylene/α‐olefin copolymerization reactions, incorporate α‐olefin molecules very poorly. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1745–1758, 2003     

Characterization of ethylene/propylene copolymers by means of a GPC-4D technique

Copolymer composition and comonomer distribution are important magnitudes in polymer material that have a big effect on different kind of properties and consequently there are several ways to study.In this work several ethylene/propylene copolymers synthesized with two different metallocene catalysts and a Ziegler–Natta catalyst and covering a wide composition range were studied. Characterization was carried out by nuclear magnetic resonance (¹³C NMR) and by gel permeation chromatography with 4 detectors (GPC-4D): refractive index, viscosity, multi-angle light scattering and infrared detectors.Different behaviour in the comonomer distribution along the molecular weight was obtained for metallocene and for ZN copolymers as expected due to the differences between these catalytic systems. Nevertheless, Ziegler–Natta copolymers present more homogeneous comonomer distribution due to the synthesis method. Study of conformation of chains in solution was improved by defining the scaling law of R_g against the number of repeat units because it avoids the effect of the repetitive unit size. Both metallocene copolymer sets show similar dependence of q value with the copolymer composition, however Ziegler–Natta copolymers show different behaviour with q values independent on copolymer composition. This different behaviour has been related with the effects of the heterogeneity of the ethylene distribution and of the molecular weight of the samples.     

C2‐symmetry dimethylated zirconocenes activated with triisobutyl aluminum as effective homogeneous catalysts for copolymerization of olefins

We investigated the catalytic performance of both bridged unsubstituted [rac‐EtInd₂ZrMe₂, rac‐Me₂SiInd₂ZrMe₂] and 2‐substituted [rac‐Et(2‐MeInd)₂ZrMe₂), rac‐Me₂Si(2‐MeInd)₂ZrMe₂] dimethylbisindenylzirconocenes activated with triisobutyl aluminum (TIBA) as a single activator in (a) homopolymerizations of ethylene and propylene, (b) copolymerization of ethylene with propylene and hexene‐1, and (c) copolymerization of propylene with hexene‐1 (at Al_TIBA/Zr = 100‐300 mol/mol). Unsubstituted catalysts were inactive in homopolymerizations of ethylene and propylene and copolymerization of propylene with hexene‐1 but exhibited high activity in copolymerizations of ethylene with propylene and hexene‐1. 2‐Substituted zirconocenes activated with TIBA were active in homopolymerizations of ethylene and propylene and exhibited high activity in copolymerization of ethylene with propylene and hexene‐1, and in copolymerization of propylene with hexene‐1. Comparative microstructural analysis of ethylene‐propylene copolymers prepared over rac‐Me₂SiInd₂ZrMe₂ activated with TIBA or Me₂NHPhB(C₆F₅)₄ has shown that the copolymers formed upon activation with TIBA are statistical in nature with some tendency to alternation, whereas those with borate activated system show a tendency to formation of comonomer blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2934–2941, 2010     

Olefin copolymerization with metallocene catalysts. I. Comparison of catalysts

A number of metallocene/methylaluminoxane (MAO) catalysts have been compared for ethylene/propylene copolymerizations to find relationship between the polymerization activities, copolymer structures, and copolymerization reactivity ratio with the catalyst structures. Stereorigid racemic ethylene bis (indenyl) zirconium dichloride and the tetrahydro derivative exhibit very high activity of 10 ⁷ g (mol Zr h bar)^?1, giving copolymers having comonomer compositions about the same as the feed compositions, molecular weights increasing with the increase of ethylene in the feed, random incorporation of comonomers, and narrow molecular weight distribution indicative of a single catalytic species. Nonbridged bis (indenyl) zirconium behaved differently, favoring the incorporation of ethylene over propylene, producing copolymers whose molecular weight decreases with the increase of ethylene in the feed, broad molecular weight distribution, and a methanol soluble fraction. This catalyst system contains two or more active species. Simple methallocene catalysts have much lower polymerization activities. C_pTiCl₂/MAO produced copolymers with tendency toward alternation, whereas Cp₂HfCl₂/MAO gave copolymer containing short blocks of monomers.     

Functionalization of polyolefins via the reaction of ozone with double bonds

Polar groups are introduced into polyolefin chains via the postpolymerization polymer-analogous transformations using the ozonolysis of side ethylidene groups of ethylene (propylene) copolymers with the cyclic comonomer 5-ethylidene-2-norbornene. The copolymers are synthesized using ansa-zirconocene catalysts Me₂Si[Ind]₂ZrCl₂/MAO, Et[Ind]₂ZrCl₂/MAO and Et[IndH₄]₂ZrCl₂/MAO, which provide insersion of the cyclic monomer into the polymer chain without ring opening. The study of number-average molecular mass and compositions of homo- and copolymers of ethylene and propylene with 5-ethylidene-2-norbornene confirms a high selectivity of the ozonolysis of unsaturated double bonds of polyolefins. The formation of polar groups in the ozonized ethylene and propylene copolymers with 5-ethylidene-2-norbornene is proved by IR and Raman spectroscopy. The thermophysical characteristics of the initial and ozonized copolymers are compared.