Unconstrained geometry complexes: Ethylene/α‐olefin copolymerizations with a tetramethyldisilyl‐bridged Cp‐amido titanium complex

Abstract

A new disilyl‐bridged complex, [(N‐tert‐butylamido)(3‐indenyl)tetramethyldisilyl]titanium dichloride (3), was synthesized and activated with methylaluminoxane (MAO) for propylene homopolymerization and ethylene/propylene and ethylene/1‐hexene copolymerizations. A polypropylene with a slight isotactic enrichment was obtained. The number of regioerrors present in the polypropylene was somewhat smaller than that found in most polypropylenes made from monosilyl‐bridged [(N‐tert‐butylamido)(3‐indenyl)dimethylsilyl]titanium dichloride. The regioerrors detected in the copolymers obtained from 3/MAO were on the order of the amounts observed in polymers made with the monosilyl‐bridged constrained geometry catalysts. Ethylene copolymers of propylene and 1‐hexene had random sequence distributions and showed significant comonomer incorporation. Because of the presence of regioerrors, a modified method for determining the monomer composition and sequence distribution was developed from the direct measurement of the monomer content from the number of methylene and methine carbons per polymer chain, regardless of propylene inversion. An estimate of the error in the copolymerization reactivity ratio determination for regioirregular ethylene/α‐olefin copolymers was obtained by the calculation of the reactivity ratios from monomer dyad sequences, with consideration given to the contribution of major regioirregular sequences. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3840–3851, 2005

The investigation of novel non‐metallocene catalysts with phenoxy‐imine ligands for ethylene (co‐)polymerization

“…In addition, the comonomer conversion is listed in Table and is in the range 2.02%–7.08%. The related results reported earlier, showed that 1‐hexene conversion was about 1%. The higher comonomer conversion confirmed that these novel non‐metallocene catalysts were favorable for the copolymerization of ethylene and 1‐hexene.…”

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

“…While the values of r E and r OD are 21.96 and 0.022, respectively, in the ethylene/1‐octadecene copolymerization. The ratio of r H / r E , r O / r E , and r OD / r E are 0.018, 0.011, and 0.0010, respectively, which can be used to compare the relative comonomer incorporation ability 41, 42. The reactivity ratio product value is an indicator for the distribution of the monomers within a polymer chain.…”

Synthesis of new 1‐decene‐based LLDPE resins and comparison with the corresponding 1‐octene‐ and 1‐hexene‐based LLDPE resins

“…One of the major contributions in metallocene single‐site technology1–7 is the preparation of linear low‐density polyethylene (LLDPE) resins with uniform molecular structures (narrow molecular weight and composition distributions) and balance (designed) physical properties 8–10. The copolymerization reaction between ethylene and high α‐olefin, such as 1‐butene, 1‐hexene, and 1‐octene, usually involves a constrained geometry catalyst (CGC), such as [(η 5 ‐C 5 Me 4 )SiMe 2 ‐(η 1 ‐NCMe 3 )]TiCl 2 , which has an opened active site for easy insertion of high α‐olefins.…”