Synthesis and catalytic properties for olefin polymerization of new vanadium complexes containing silsesquioxane ligands with different denticity
A supported titanium postmetallocene catalyst: Effect of selected conditions on ethylene polymerization
Ethylene polymerization with a titanium complex [N,N-ethylenebis(3-methoxysalicylideneiminato)titanium dichloride] immobilized on the magnesium support with the formula MgCl2(THF)0.32(Et2AlCl)0.36 was studied. In particular, the effects of polymerization temperature, monomer pressure, and polymerization time on the activity of the catalyst and on the polyethylene properties (molecular weight and its distribution, melting point, crystallinity, and bulk density) were evaluated. The findings of investigations prove that the studied supported titanium catalyst is highly active in ethylene polymerization, and its activity increases with increasing temperature and monomer pressure. Moreover, stab…
Synthesis and catalytic performance in ethylene and 1-octene polymerization of chlorotitanium(IV) silsesquioxane complexes. Effect of increasing ligand denticity and type of nonreactive organic substituents
Abstract The series of titanasilsesquioxanes that differ in a way of binding to the transition metal ( via one, two or three oxygen atoms) and type of nonreactive substituents bonded to inorganic oxygen-silicon cage ( i -Bu, Ph, c -C 6 H 11 ) were prepared by reacting of TiCl 4 with 1 eqv. of the silsesquioxane ligand. Upon treatment with an appropriate cocatalyst, all titanium precatalysts are active in ethylene and 1-octene polymerization and produce from low to high molecular weight polyethylenes and moderately ([ mmmm ] = 44–74%) isotactic poly(1-octene)s. The influence of polymerization parameters, type of cocatalyst and the silsesquioxane structure on the catalytic behavior of the tit…
Studies on the microstructure of ethylene/1-hexene copolymers prepared over heterogeneous Ziegler - Natta catalysts
Three MgCl 2(THF) 2-supported, AlEt 2Cl-activated VOCl 3, VCl 4 and TiCl 4 Ziegler - Natta catalysts were used to copolymerize ethylene with 1-hexene in the presence of hydrogen to prepare low-M well-soluble copolymers that could be analyzed by 13C-NMR. The spectra (Fig. 1) showed resonance signals due to ethylene and 1-hexene units in positions unaffected by catalyst type and with intensities related to the degree of comonomer incorporation into the copolymer. The triad sequence distribution and comonomer reactivity ratios (r) were calculated by the Randall method [11] and Bernoulli statistics based on the known copolymer composition. The latter appeared to be the more valid in predicting …
2,4-Di-tert-butyl-6-({[2-(di-methyl-amino)-eth-yl](2-hy-droxy-benz-yl)amino}-meth-yl)phenol.
The title compound, C26H40N2O2, has both its N atoms in trigonal-pyramidal geometries. The molecular structure is stabilized by O—H...N and C—H...O hydrogen bonds. In the crystal, C—H...π interactions lead to the formation of a supramolecular helical chain along theb-axis direction.
Homopolymerization of styrenic monomers and their copolymerization with ethylene using group 4 non‐metallocene catalysts
Homopolymerization of styrenic monomers (St, p ‐Me‐St, p ‐t Bu‐St, p ‐t BuO‐St) and their copolymerization with ethylene, with the use of [( t Bu2O2NN′)ZrCl]2(μ‐O) (1 ) and ( t Bu2O2NN′)TiCl2 (2 ), where t Bu2O2NN′ = Me2N(CH2)2N(CH2‐2‐O−‐3,5‐t Bu2‐C6H2)2, is explored in the presence of MMAO and (i Bu)3Al/Ph3CB(C6F5)4. The ethylene/styrenic monomers copolymerization with 1 /MMAO produces exclusively copolymers with high activity and good comonomer incorporation whereas the other catalytic systems yield mixtures of copolymers and homopolymers. The use of p ‐alkyl styrene derivatives instead of styrene raises the catalytic activity, comonomer incorporation and molecular weights of the copolyme…
Synthesis of oxide-supported vanadium catalysts and their activity in ethylene polymerization
Copolymerization of ethylene with 1‐hexene over metallocene catalyst supported on complex of magnesium chloride with tetrahydrofuran
The study of ethylene/1-hexene copolymerization with the zirconocene catalyst, bis(cyclopentadienyl)zirconium dichloride (Cp 2 ZrCl 2 )/methylaluminoxane (MAO), anchored on a MgCl 2 (THF) 2 support was carried out. The influence of 1-hexene concentration in the feed on catalyst productivity and comonomer reactivity as well as other properties was investigated. Additionally, the effect of support modification by the organoaluminum compounds [(MAO, trimethylaluminum (AlMe 3 ), or diethylaluminum chloride (Et 2 AlCl)] on the behavior of the MgCl 2 (THF) 2 /Cp 2 ZrCl/MAO catalyst in the copolymerization process and on the properties of the copolymers was explored. Immobilization of the Cp 2 ZrC…
Tri-alkenyl polyhedral oligomeric silsesquioxanes as comonomers and active center modifiers in ethylene copolymerization catalyzed by bis(phenoxy-imine) Ti, Zr, V and V salen-type complexes
Abstract In copolymerization of ethylene (E) with tri-alkenyl-silsesquioxanes (POSS-6-3 and POSS-10-3) were used bis(phenoxy-imine) titanium, zirconium and vanadium catalysts, as well as salen-type vanadium catalysts. There were obtained copolymers with POSS-R-3 units as side branches of polymer chains. The type of employed bis(phenoxy-imine) titanium, zirconium and vanadium catalysts and salen-type catalyst of vanadium determined the copolymer chain termination reactions, as well as the mechanism of modification of the active species by the POSS-R-3 comonomer. POSS-R-3 comonomers caused selective poisoning of bis(phenoxy-imine) zirconium catalyst and they provided protection against tight …
Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization
Oxovanadium(IV) complexes with (ONNO)-type tetradentate Schiff base ligands: salen, acacen, aceten, acetph (H2salen = N,N'-ethylenebis(salicylideneimine), H2aceten = N,N'-ethylenebis(2-hydroxyacetophenoneimine), H2acacen = N,N'-ethylenebis(acetylacetonimine), H 2 acetph = N ,N ' -phenylene-1,2-b is (2-hydroxyacetophenoneimine)), were the first time investi- gated in ethylene polymerization and ethylene/1-octene copo- lymerization processes. In general, all these complexes are moderately active precatalyst for ethylene polymerization up- on activation with EtAlCl2 and they give high molecular weight linear polyethylenes. Their activity in copolymeriza- tion was found relatively low. However,…
Ethylene/POSS copolymerization behavior of postmetallocene catalysts and copolymer characteristics
Copolymerization of ethylene with iso-butyl substituted monoalkenyl(siloxy)- or monoalkenylsilsesquioxane (POSS) comonomers over bis(phenoxy-imine) and salen-type titanium and zirconium catalysts was studied. It was found that the polyreaction performance was significantly depended by the kind of the catalyst and by the structure and concentration of POSS in the feed. The POSS comonomer was efficiently incorporated into the polymer chain at up to 0.2 mol %. The differences in the copolymer compositions as the functions of the catalyst kind and the POSS comonomer were observed, including the varied number-average sequence length of ethylene and unsaturated end groups, as determined by 1H NMR…
Synthesis, characterization and ethylene polymerization by metallasilsesquioxane
Soluble complexes of group (IV) metallocenes anchored on a substituted polyhedral oligomeric silsesquioxane trisilanol support were prepared and characterized. These catalyst precursors formulated as [M(O^O^O)X] are found to be active in polymerization of ethylene at high temperature in combination with ethylaluminum sesquichloride (Et3Al2Cl3, EASC) as co-catalyst. The polyethylene obtained by these catalysts is linear, crystalline and displays narrow dispersity. The unique low molecular weight PE formed in this reaction exhibits properties comparable to commercial micronized PE waxes that have potential industrial applications in surface coating and ink formulations. Copyright © 2013 John …
Dichlorovanadium(IV) diamine-bis(phenolate) complexes for ethylene (co)polymerization and 1-olefin isospecific polymerization
Abstract Two vanadium complexes bearing amine-bis(phenolate) ligands with the amino side-arm donor, [V{Me2NCH2CH2N(CH2-2-O-3,5-tBu2-C6H2)2}Cl2] (1) and [V{Me2NCH2CH2N(CH2-2-O-3,5-tBu2-C6H2)(CH2-2-O-C6H4)}Cl2] (2), were synthesised and characterized by FTIR and 1H NMR spectroscopy. Upon activation with Al(iBu)3/Ph3CB(C6F5)4, these complexes became active catalysts for 1-octene polymerization giving highly stereoregular polymers (mmmm ∼ 90%) having regioirregularly arranged units. The catalytic activity of the catalysts in ethylene homo- and copolymerization, and their ability to incorporate a comonomer were highly dependent on both the activator type and the complex structure. 1/EtAlCl2 exhi…
Transition metal complexes of tetradentate and bidentate Schiff bases as catalysts for ethylene polymerization: Effect of transition metal and cocatalyst
This article compares catalytic performance of ethylene polymerization in similar polymerization conditions of transition metal complexes having two ligands [O,N] (phenoxy-imine) and having one tetradentate ligand [O,N,N,O] (salphen or salen). It is shown that the activity of both complex types as well as the product properties depend in the same way on the type of central metal in the complex and on the cocatalyst used. Although the type of ligand has some effect on the catalyst activity, yet it does not control the properties of the obtained products. The vanadium and zirconium complexes, irrespective of the cocatalyst used, yield linear polyethylene with high molecular weight (a few hund…
Polypropylene and poly(ethylene-co-1-octene) effective synthesis with diamine-bis(phenolate) complexes: Effect of complex structure on catalyst activity and product microstructure
A series of group 4 metal complexes bearing amine-bis(phenolate) ligands with the amino side-arm donor: (μ-O)[Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)2ZrCl]2 (1a), R2N(CH2)2N(CH2-2-O-3-R1-5-R2-C6H2)2TiCl2 (R = Me, R1, R2 = tBu (2a), R = iPr, R1, R2 = tBu (2b), R = iPr, R1 = tBu, R2 = OMe (2c)), and Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)(CH2-2-O-C6H4)TiCl2 (2d) are used in ethylene and propylene homopolymerization, and ethylene/1-octene copolymerization. All complexes, upon their activation with Al(iBu)3/Ph3CB(C6F5)4, exhibit reasonable catalytic activity for ethylene homo- and copolymerization giving linear polyethylene with high to ultra-high molecular weight (600·× 103–3600·× 103 g/mol). The activi…
Vanadium complex with tetradentate [O,N,N,O] ligand supported on magnesium type carrier for ethylene homopolymerization and copolymerization
Immobilization of 1,2-cyclohexylenebis(5-chlorosalicylideneiminato)vanadium dichloride on the magnesium support obtained in the reaction of MgCl 2 .3.4EtOH with Et 2 AlCl gives a highly active precursor for ethylene homopolymerization and its copolymerization with 1-octene. This catalyst exhibits the highest activity in conjunction with MAO, but it is also highly active with AlMe 3 as a cocatalyst. On the other hand, when combined with chlorinated alkylaluminum compounds, Et 2 AlCl and EtAlCl 2 , it gives traces of polyethylene. Moreover, its catalytic activity is strongly affected by the reaction temperature: it increased with rising polymerization temperature from 20 °C to 60 °C, The kine…
Copolymerization of Ethylene with Selected Vinyl Monomers Catalyzed by Group 4 Metal and Vanadium Complexes with Multidentate Ligands: A Short Review
This paper gives a short overview of homogeneous post-metallocene catalysts based on group 4 metal and vanadium complexes bearing multidentate ligands. It summarizes the catalytic behavior of those catalysts in copolymerization of ethylene with 1-olefins, with styrenic monomers and with α,ω-alkenols. The review is focused on finding correlations between the structure of a complex, its catalyst activity and comonomer incorporation ability, as well as the microstructure of the copolymer chains.
Vanadium-based Ziegler-Natta catalyst supported on MgCl2(THF)2 for ethylene polymerization
A supported magnesium‐vanadium‐aluminium catalyst was prepared by depositing –with the use of a milling technique–VOCl3 on the MgCl2(THF)2 support and subsequent activation with diethylaluminium chloride. Catalytic activity of the obtained system for ethylene polymerization was evaluated as a function of Mg/V and Al/V ratios as well as catalyst ageing time and polymerization temperature. High concentrations of THF in the catalytic system and considerable excess of an organoaluminium co‐catalyst were found to have no deactivating action on vanadium active sites. The catalyst obtained is stable and its activity for ethylene polymerization is high. It yields polyethylene with higher molecular …
Synthesis, characterization and catalytic properties for olefin polymerization of two new dimeric zirconium(IV) complexes having diamine-bis(phenolate) and chloride ligands
Abstract Reaction of the zirconium tetrachloride with one equivalent of the sodium salt of the diamine bis (phenolate) ligand, L1H2 (Me2NCH2CH2N-(CH2-2-OH-3,5-tBu-C6H2)2) or L2H2 (Me2NCH2CH2N-(CH2-2-OH-3,5-tBu-C6H2)(CH2-2-OH-C6H4)) in the presence of air led to formation of [Lig1ZrCl]2(μ-O) and [Lig2ZrCl]2(μ-O), respectively. These novel oxo-bridged dinuclear zirconium complexes were characterized by elemental analysis, 1H NMR spectroscopy and by single-crystal X-ray diffraction. Their reactivities in polymerization of ethylene and 1-octene, upon activation with Al(iBu)3/Ph3CB(C6F5)4 and MAO, were examined. It was found that lack of t-Bu substituents on one phenolate ring cause a significan…
Synthesis and catalytic studies of Ti-anchored disilanol isobutyl-POSS/alkylaluminum system
Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
Dichlorovanadium (IV) complexes with salen-type ligands for ethylene polymerization
Vanadium complexes with tetradentate salen-type ligands were first time explored in ethylene polymerizations. The effects of the vanadium complex structure, the alkyl aluminum cocatalysts type (EtAlCl2, Et2AlCl, Et3Al, and MAO), and the polymerization conditions (Al/V molar ratio, temperature) on polyethylene yield were explored. It was found that EtAlCl2 in conjunction with investigated vanadium complexes produced the most efficient catalytic systems. It was shown, moreover, that the structural changes of the tetradentate salen ligand (type of bridge which bond donor nitrogen atoms and type of substituent on aryl rings) affected activity of the catalytic system. The complexes containing li…
Ethylene/1-olefin copolymerization behaviour of vanadium and titanium complexes bearing salen-type ligand
Ethylene/1-olefin copolymerization using vanadium and titanium complexes bearing tetradentate [O,N,N,O]-type ligand and EtAlCl2 or MAO as a cocatalyst is carried out. In the presence of the vanadium complex activated with EtAlCl2 is observed (a) negative “comonomer effect”, (b) high comonomer incorporation and narrow chemical composition distribution (CCD), (c) unexpected copolymer microstructure, and (d) increased molecular weight of copolymers when compared with the homopolymer. In contrast, titanium catalyst gives copolymers with lower 1-olefin content and broad CCD. Supported complexes show higher activity, lower 1-olefins incorporation and give copolymers with ultra high molecular weig…
Studies of structural composition distribution heterogeneity in ethylene/1-hexene copolymers using thermal fractionation technique (SSA)
Abstract Investigations into the compositional heterogeneity of ethylene/1-hexene copolymers obtained with various zirconocene/MAO catalysts, either homogeneous or supported on inorganic carriers such as a complex of magnesium chloride with tetrahydrofuran or methyl alcohol, were conducted. The dependence between metallocene structure, as well as catalyst immobilization, and the compositional heterogeneity of the related products was investigated. It was found that the heterogeneity of copolymers is determined by the metallocene catalyst structure. The amount of peaks on the DSC thermograms of copolymers and their division increase with the increase of bulkiness of the ligand in the catalyt…
Olefin polymerization and copolymerization by complexes bearing [ONNO]-Type salan ligands: Effect of ligand structure and metal type (titanium, zirconium, and vanadium)
A series of novel titanium(IV) complexes bearing tetradentate [ONNO] salan type ligands: [Ti{2,2′-(OC6H3-5-t-Bu)2-NHRNH}Cl2] (Lig1TiCl2: R = C2H4; Lig2TiCl2: R = C4H8; Lig3TiCl2: R = C6H12) and [Ti{2,2′-(OC6H2-3,5-di-t-Bu)2-NHC6H12NH}Cl2] (Lig4TiCl2) were synthesized and used in the (co)polymerization of olefins. Vanadium and zirconium complexes: [M{2,2′-(OC6H3-3,5-di-t-Bu)2-NHC6H12NH}Cl2] (Lig4VCl2: M = V; Lig4ZrCl2: M = Zr) were also synthesized for comparative investigations. All the complexes turned out active in 1-octene polymerization after activation by MAO and/or Al(i-Bu)3/[Ph3C][B(C6F5)4]. The catalytic performance of titanium complexes was strictly dependent on their structures an…
Ethylene polymerization with FI complexes having novel phenoxy-imine ligands: Effect of metal type and complex immobilization
A series of bis(phenoxy-imine) vanadium and zirconium complexes with different types of R3 substituents at the nitrogen atom, where R3 = phenyl, naphthyl, or anthryl, was synthesized and investigated in ethylene polymerization. Moreover, the catalytic performance was verified for three supported catalysts, which had been obtained by immobilization of bis[N-(salicylidene)-1-naphthylaminato]M(IV) dichloride complexes (M = V, Zr, or Ti) on the magnesium carrier MgCl2(THF)2/Et2AlCl. Catalytic performance of both supported and homogeneous catalysts was verified in conjunction with methylaluminoxane (MAO) or with alkylaluminium compounds (EtnAlCl3−n, n = 1–3). The activity of FI vanadium and zirc…
Effect of AlR3 (R = Me, Et, iBu) addition on the composition and microstructure of ethylene/1-olefin copolymers made with post-metallocene complexes of group 4 elements
The effect of trialkylaluminum compound (AlR3, where R = Me, Et, iBu) addition on the performance of the [LigZrCl]2(μ-O)/AliBu3/Ph3CB(C6F5)4 and LigTiCl2/AliBu3/Ph3CB(C6F5)4 (Lig = Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)2) catalysts in ethylene/1-olefin copolymerization was investigated. The presence of AlMe3 in the feed during the copolymerization process catalyzed by the diamine-bis(phenolate) zirconium catalyst greatly increases the amount of incorporated comonomer and leads to microstructural changes, e.g., the formation of blocky and alternating sequences of 1-olefin units. Moreover, the use of AlMe3 limits the reaction yield and decreases the molecular weight of the produced copolymers. Th…
Effective copolymerization of ethylene with α,ω-alkenols and homopolymerization of α,ω-alkenols catalyzed by aminophenolate zirconium complex
Abstract A zirconium complex of diamine-bis(phenolate) ligand, [(tBu2O2NN’)ZrCl]2(μ-O) where (tBu2O2NN’) = Me2N(CH2)2N(CH2–2-O−-3,5-tBu2-C6H2)2, activated with (iBu)3Al/Ph3CB(C6F5)4, was for the first time used in copolymerization of ethylene with unsaturated alcohols (CH2 = CH(CH2)nCH2OH, where n = 7, 8, 3). The hydroxyl groups of comonomers were protected with R3-xAlClx (where x = 0 or 1, R = iBu, Et). In contrast to the formerly reported catalysts, the activity of this catalyst is much higher in ethylene/alkenols copolymerization than in ethylene homopolymerization and its lifetime is long. Moreover, the copolymers with high polar comonomer contents (up to 16.4 mol%, 52.3 wt%) were produ…
A comparative study on the polymerization of 1-octene promoted by vanadium and titanium complexes supported by phenoxyimine and salen type ligands
Polymerizations of 1-octene were carried out in the presence of vanadium and titanium complexes bearing salen-type or phenoxyimine ligands activated with various co-catalysts. Vanadium complexes turned out active only in conjunction with MAO, whereas the titanium ones were active in combination with Al(i-Bu)3/Ph3CB(C6F5)4. The activity of all catalysts was moderate or low and it was dependent on the ligand type: bis(phenoxyimine) complexes were more active than the salen ones. Both vanadium and titanium catalytic systems produced poly(1-octene)s possessing atactic structures with [mmmm] sequences in the range from 12 to 56 % at room temperature. A temperature decrease to 0.5 °C for the reac…
Chlorotitanium (IV) tetradentate Schiff-base complex immobilized on inorganic supports: Support type and other factors having effect on ethylene polymerization activity
A titanium complex with [O,N,N,O]-type tetradentate Schiff base (LTiCl2), never used before in polymerization of olefins, was immobilized on silica- and magnesium-type carriers, and it was used in ethylene polymerization. The conducted research revealed that the catalytic properties of the complex LTiCl2 supported on those carriers were different for both the catalytic systems studied, and simultaneously they turned out different from those of the unsupported system. The supported catalysts require the use of Me3Al, Et3Al, or MAO as the activator to be able to offer high catalytic activities, whereas Et2AlCl is needed for the nonsupported catalyst. This finding, together with considerable c…
Ethylene homo- and copolymerization catalyzed by vanadium, zirconium, and titanium complexes having potentially tridentate Schiff base ligands
Abstract New potentially tridentate Schiff base ligands, 2-[({4-[(3-N,N-dimethylamino)propyl] phenyl}imino)methyl]-4,6-di-tert-butylphenol (L1H) and 2-[{2-(N-phenyl-N-methylaminomethyl)-phenylimino}-methyl]-4,6-di-tert-butylophenol (L2H) were prepared and after deprotonation they were reacted with VOCl3 or MCl4 (where M = Zr or Ti) to produce corresponding complexes (L1-V, L2-V, L1-Zr, L2-Ti) with good yields. All new compounds were characterized by the 1H and 13C NMR as well as FTIR spectroscopic methods. Upon activation with Et2AlCl or EtAlCl2, both the vanadium complexes exhibited exceptionally high catalytic activities in the ethylene polymerization (up to 69,000 kg/(molV⋅h) for L1-V an…
Synthesis and characterization of ethylene-1-hexene copolymers prepared by using MgCl2(THF)2-supported Ziegler-Natta catalysts
Ethylene was copolymerized with 1-hexene over vanadium (VOCl3 and VCl4) and titanium (TiCl4) catalysts supported on MgCl2(THF)2 and activated with Et2AlCl. So far these catalyst systems have not been known as initiators of ethylene-1-hexene copolymerization. The vanadium catalysts were more active than the titanium catalyst and, at identical comonomer concentrations in the feed, gave rise to a greater incorporation of 1-hexene into the copolymer. Even at relatively low fractions of 1-hexene, the MgCl2(THF)2-supported catalysts affected much the copolymer properties like density, melting point and crystallinity.
Ethylenebis(5-chlorosalicylideneiminato)vanadium dichloride immobilized on MgCl2 -based supports as a highly effective precursor for ethylene polymerization
Ethylenebis(5-chlorosalicylideneiminato)vanadium dichloride supported on MgCl2(THF)2 or on the same carrier modified by EtnAlCl3−n, where n = 1–3, was used in ethylene polymerization in the presence of MAO or a common alkylaluminium compounds as a cocatalyst. The support type alter vanadium loading and also change the characteristic of the catalytic active sites. Et2AlCl is the best activator for a catalyst which has been immobilized on a nonmodified support, whereas the systems which contain a carrier which has been modified by an organoaluminium compound reveal the highest activity in conjunction with MAO. That difference, together with different temperature effects on polymerization effi…
(Co)polymerisation Behaviour of Supported Metallocene Catalysts: Carrier Effect
The polymerisation and copolymerisation of ethylene with 1-hexene over metallocene catalysts L 2 ZrCl 2 / MAO (L = Cp, n-BuCp, t-BuCp, i-PrCp, Me 5 Cp) supported on different types of carriers (MgCl 2 (MeOH) 6 or silica with CH 3 surface groups obtained in the sol-gel process) were studied. It was demonstrated that both the metallocene structure and the type of inorganic support affected catalyst activity and polymer properties such as melting point, molecular weight and molecular weight distribution. The metallocene structure also determined comonomer incorporation, both for homogeneous and supported catalytic systems. When a catalyst is anchored on a support, it becomes less effective at …
Synthesis and olefin homo- and copolymerization behavior of new vanadium complexes bearing [OSSO]-type ligands
Novel vanadium complexes bearing [OSSO]-type ligands having two phenolato units linked through the –CH2S(CH2)4SCH2– (1V) or –CH2S(CH2)2SCH2– (2V) bridge are synthesized with good yields by reacting a deprotonated ligand with VCl4. They are then used in ethylene (co)polymerization after activation with EtAlCl2 and Et2AlCl. In the presence of EtAlCl2, both complexes promote ethylene polymerization with very high activities, over 4 × 107 g/(mol h), leading to PEs with high molecular weight and narrow molecular weight distribution. The prepared complexes exhibit lower activity for ethylene/1-octene copolymerization. It is also revealed that the catalyst based on the –CH2S(CH2)4SCH2– bridged com…
Effect of hydrogen on the ethylene polymerization process over Ziegler-Natta catalysts supported on MgCl2(THF)2. I. Studies of the chain-transfer reaction
The effect of hydrogen on the molecular weight of polyethylene obtained over vanadium catalysts (based on VCl4 and VOCl3) supported on MgCl2(THF)2 was studied and the results were compared to those obtained for similar titanium catalysts. It was confirmed that the dependencies of the transfer reaction on the hydrogen concentration are a half-order in all investigated systems. However, the transition metal of the catalytic site affects the ratio of the transfer rate with hydrogen to the propagation rate (ktr,H/kp) and the results showed that hydrogen is a more effective agent of polyethylene molecular weight control in vanadium-based systems as compared to the titanium catalyst. © 2000 John …
Synthesis and structural characterization of ethylene copolymers containing double-decker silsesquioxane as pendant groups and cross-linkage sites by coordinative copolymerization
Abstract The copolymers of ethylene with the double-decker silsesquioxane (DDSQ) were synthesized by copolymerization with the use of metallocene and bis(phenoxy-imine) catalysts. The influence of the kind of the catalyst and polyreaction conditions on the performance of copolymerization as well as on the properties of the copolymers was studied. Depending on polyreaction parameters, the DDSQ contents in the copolymer varied in the range of 0.93–11.53 wt% which determined the compositions and the structural properties of copolymers. DDSQ incorporated into the polymer chain could constitute pendant groups in the main chain or it could act as a cross-linking agent. The ethylene/DDSQ copolymer…
The effect of the comonomer on the copolymerization of ethylene with long chain α-olefins using Ziegler–Natta catalysts supported on MgCl2(THF)2
Abstract The effect of the type of the comonomer (1-pentene, 1-hexene, 1-octene, 1-decene and 1-dodecene) on the copolymerization of ethylene with α-olefin over vanadium (VOCl3 and VCl4) and titanium (TiCl4) catalysts supported on MgCl2(THF)2 and activated by Et2AlCl was studied. The results show that the introduction of a longer α-olefin in the ethylene polymerization feed depresses the catalytic activity of all investigated catalysts. The catalyst activity does not depend on the type of the comonomer applied but changes with the comonomer concentration in the feed. The incorporation of α-olefin in the polymer chain was found to be dependent on the type and concentration of the comonomer i…
Titanium (IV) chloride complexes with salen ligands supported on magnesium carrier: Synthesis and use in ethylene polymerization
The magnesium support with the formula MgCl 2 (THF) 0.32 (Et 2 AlCl) 0.36 was used for immobilization of salen complexes of titanium [Ti(salen)Cl 2 , Ti(salen(O-Me) 2 )Cl 2 ]. The effects of the catalyst composition (i.e. type of titanium complex and type of activator), polymerization temperature, polymerization time, and the effect of comonomer (1-octene) on the activity of the obtained supported catalysts, on the polymer characteristics (molecular weight, molecular weight distribution, melting point), and on the polymer morphology were studied. The findings were compared to those obtained for corresponding unsupported systems. Catalysts immobilization results in considerable changes in ca…
Microstructure of ethylene-1-hexene and ethylene-1-octene copolymers obtained over Ziegler–Natta catalysts supported on MgCl 2 (THF) 2
Abstract The ethylene copolymerizations with 1-hexene or 1-octene in the presence of hydrogen using three catalysts, MgCl 2 (THF) 2 /VOCl 3 /Et 2 AlCl, MgCl 2 (THF) 2 /VCl 4 /Et 2 AlCl, MgCl 2 (THF) 2 /TiCl 4 /Et 2 AlCl, were investigated. It was found that the addition of hydrogen into the copolymerization feed reduces the molecular weight of the copolymers produced and decreases the activity of all the studied catalysts. The microstructure of the copolymers obtained was determined on the basis of 13 C NMR investigations and the reactivity ratios of the comonomers were calculated. The lack of tendency of the olefin comonomers to the creation of the polymer block was confirmed. It was found…
Organometallic vanadium‐based heterogeneous catalysts for ethylene polymerization. Study of the deactivation process
Slurry polymerizations of ethylene over vanadium catalysts (based on VCl4 and VOCl3) and their MgCl2(THF)2-supported equivalents were studied. Unsupported vanadium catalysts were found to be unstable while the vanadium active sites deposited on the MgCl2(THF)2 complex are stable. A sharply outlined correlation was found between the concentration of vanadium(III) and catalyst productivity. The high activity and stability of the vanadium catalyst when supported on the magnesium complex is attributed to the increase of resistance to reduction of active vanadium(III) to inactive vanadium(II) by an organoaluminium co-catalyst.
Effect of hydrogen on the ethylene polymerization process over Ziegler-Natta catalysts supported on MgCl2(THF)2. II. Kinetic studies
This article reports on a study of the effects of hydrogen on the activity of vanadium and titanium catalysts supported on MgCl 2 (THF) 2 in ethylene polymerization. It was found that hydrogen did not change the stable nature of the active sites and the polydispersity index of the polyethylene obtained. The propagation rate, expressed as k p , was found to be independent of the presence and concentration of hydrogen, indicating that this reacting agent does not modify the reactivity of the active sites. However, the presence of hydrogen in the polymerization medium is responsible for partial deactivation of the active sites just before polymerization is initiated.
Styrene polymerization using nickel(II) complexes as catalysts
International audience; Styrene polymerization is investigated with neutral and cationic Ni(II) complexes, i.e. Ni(bipy)Me-2, 1, Ni(bipy)Br-2, 2, Ni(phen)Br-2, 3, or Ni(Me(2)phen)Br-2, 4, Ni(acac)(2), 5, (bipy = 2,2 '-bipyridine, phen = phenanthroline, Me,phen = 2,9-dimethyl-1, 10-phenanthroline, acac acetylacetonate), activated by [NHMe2Ph][B(C6F5)(4)] or B(C6F5)(3) as cocatalysts, in the presence of AlMe3. The influence on the polystyrene features and the reaction kinetics of the nickel complex and boron activator, the Al/Ni or B/Ni molar ratios as well as the monomer concentration are studied. Catalytic systems derived from 2, 3 or 5 and [NHMe2Ph][B(C6F5)(4)] at a Ni:B:Al ratio of 1: 1:5…
Ring opening polymerization of ε-caprolactone initiated by titanium and vanadium complexes of ONO-type schiff base ligand
AbstractA phenoxy-imine proligand with the additional OH donor group, 4,6-tBu2-2-(2-CH2(OH)-C6H4N = CH)C6H3OH (LH2), was synthesized and used to prepare group 4 and 5 complexes by reacting with Ti(OiPr)4 (LTi) and VO(OiPr)3 (LV). All new compounds were characterized by the FTIR, 1H and 13C NMR spectroscopy and LTi by the single-crystal X-ray diffraction analysis. The complexes were used as catalysts in the ring opening polymerization of ε-caprolactone. The influence of monomer/transition metal molar ratio, reaction time, polymerization temperature as well as complex type was investigated in detail. The complexes showed high (LTi) and moderate (LV) activity in ε-caprolactone polymerization a…
(Co)polymerization behavior of supported metallocene catalysts. I. Ligand and substituent effect
Ethylene polymerization and its copolymerization with 1-hexene with a set of supported metallocene catalysts were studied. As a carrier, the complex of mag- nesium chloride with tetrahydrofuran, which was previously pretreated with a triiso- butylaluminium (TIBA), was used. The investigated metallocene compound differs in the metal type (Zr or Ti), the nature of the alkyl substituent in the cyclopentadienyl ring, and the type of ligand (Cp or Ind). The effect of catalyst composition on the anchored metal content, catalyst activity, comonomer reactivity, and polymer proper- ties was investigated. The results obtained with supported catalysts were compared with those obtained with their homog…
Effect of catalyst composition on chain-end-group of polyethylene produced by salen-type complexes of titanium, zirconium, and vanadium
Novel diamine-bis(phenolate) Ti(IV) complexes – tuning the complex structure to control catalytic properties in α-olefin polymerization
Abstract Four monomeric titanium(IV) dichloride complexes of amine-bis(phenolate) ligands having an extra donor arm (2a–2d) and one oxo-bridged complex 3 were successfully synthesized in the reaction of TiCl4 with a sodium salt of the appropriate ligand, and they were characterized by 1H NMR spectroscopy. The ligands had either a dimethylamino side‐arm donor and t-Bu substituents on both (1a) and one (1d) phenolate rings or a diisopropylamino side-arm donor and t-Bu (1b) and t-Bu along with OMe (1c) phenolate substituents. All complexes upon activation with [Ph3CB(C6F5)4] and MAO were used to catalyze polymerization of 1-octene (in liquid monomer) into poly(1-octene). Their activities as we…
CCDC 1877301: Experimental Crystal Structure Determination
Related Article: Julia Fryga, Marzena Białek, Grzegorz Spaleniak, Błażej Dziuk|2021|J.Poly.Res.|28||doi:10.1007/s10965-021-02419-y
CCDC 999524: Experimental Crystal Structure Determination
Related Article: Elwira Bisz, Marzena Białek, Bartosz Zarychta|2015|Appl.Catal.,A|503|26|doi:10.1016/j.apcata.2015.06.033