Ethylene/α‐olefin copolymerization by nonbridged (cyclopentadienyl)(aryloxy)titanium(IV) dichloride/AlⁱBu₃/Ph₃CB(C₆F₅)₄ catalyst systems

Abstract

A series of nonbridged (cyclopentadienyl) (aryloxy)titanium(IV) complexes of the type, (η5‐Cp′)(OAr)TiCl2 [OAr = O‐2,4,6‐tBu3C6H2 and Cp′ = Me5C5 (1), Me4PhC5 (2), and 1,2‐Ph2‐4‐MeC5H2 (3)], were prepared and used for the copolymerization of ethylene with α‐olefins (e.g., 1‐hexene, 1‐octene, and 1‐octadecene) in presence of AliBu3 and Ph3CB(C6F5)4 (TIBA/B). The effect of the catalyst structure, comonomer, and reaction conditions on the catalytic activity, comonomer incorporation, and molecular weight of the produced copolymers was examined. The substituents on the cyclopentadienyl group of the ligand in 1–3 play an important role in the catalytic activity and comonomer incorporation. The 1/TIBA/B catalyst system exhibits the highest catalytic activity, while the 3/TIBA/B catalyst system yields copolymers with the highest comonomer incorporation under the same conditions. The reactivity ratio product values are smaller than those by ordinary metallocene type, which indicates that the copolymerization of ethylene with 1‐hexene, 1‐octene, and 1‐octadecene by the 1–3/TIBA/B catalyst systems does not proceed in a random manner. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Ethylene/1-olefin copolymerization behaviour of vanadium and titanium complexes bearing salen-type ligand

“…6. This spectrum is similar to those presented in other works for copolymers with not very high comonomer content [29,44] The spectra of poly(ethylene-co-1-octene)s and poly(ethylene-co-1-decene)s synthesized with vanadium catalyst turned out to be quite different from typical spectra of ethylene/1-olefin copolymers known from literature and the signal assignment and the copolymerization mechanism in the presence of vanadium catalyst needs further detail examination.…”

“…Such behaviour of catalyst is not typical for ethylene/1-olefin copolymerization. Usually, decline in molecular weights versus increasing comonomer concentrations is observed for different catalyst types which may be attributed to elimination of bhydride [5,11,29]. The obtained ethylene/1-octene copolymers possessed the moderate values of M w /M n , Moreover, M w /M n values were independent on the amount of 1-octene in the copolymerization feed in practice, and they fell within 5.54-6.95.…”

“…The opposite relation is usually observed, i.e. long chain 1-olefins have lower incorporation levels into polyethylene chains due to lower coordination ability of bulkier 1-olefins [29][30][31].…”

Vanadium Modification Effects on the (SiO2/MgO/MgCl2)•TiClxZiegler-Natta Polyethylene Catalyst

“…Decline in molecular weight versus the increasing comonomer concentrations may be due to the following reasons: fi rst, the enhanced β-H chain transfer after the insertion of 1-hexene comonomer resulted in lower MW of the copolymers. [ 51,58 ] Second, presence of 1-hexene greatly increased the amount of polymer produced by low-MW sites because these sites more easily incorporate comonomer than high-MW sites do. [ 38,59,60 ] Ethylene consumption rates were drastically increased with the addition of 1-hexene as shown in the copolymerization kinetic curves ( Figure 6 and Figure S10, Supporting Information), which was corresponding to the increased activity.…”

Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization

“…2 that the molecular weight of polyethylene obtained with [VO(acacen)]/EtAlCl 2 is much higher than that for copolymers, and that it decreases with the increase of comonomer concentration in the feed. Such effects were observed repeatedly for copolymerizations catalyzed by different catalytic systems [21,[35][36][37][38]. Lower molecular weights of polymers for increasing 1-octene concentrations may result from the chain transfer to comonomer and/or more favourable β-hydride elimination after comonomer incorporation.…”