Significant proximity and cocatalyst effects in binuclear catalysis for olefin polymerization

Hongbo Li; Charlotte L. Stern; Tobin J. Marks

doi:10.1021/ma050959c

Significant proximity and cocatalyst effects in binuclear catalysis for olefin polymerization

Hongbo Li, Charlotte L. Stern, Tobin J. Marks

Northwestern University

Research output: Contribution to journal › Article

77 Citations (Scopus)

Abstract

We describe here the implementation of methylene-bridged binuclear "constrained geometry catalyst" (μ-CH ₂-3,3′) {(η ⁵-indenyl)[1-Me ₂Si( ^tBuN)](ZrMe ₂)} ₂ (Cl-Zr ₂) to produce high-M _w branched polyethylene. In ethylene homopolymerization, ∼70x increases in molecular weight are achieved with (C1-Zr ₂) vs (μ-CH ₂CH ₂-3,3′){(η ⁵-indenyl)[1-Me ₂Si( ^tBuN)](ZrMe ₂)} ₂ (C2-Zr ₂) under identical polymerization conditions using (Ph ₃C ⁺) ₂[1,4-(C ₆F ₅) ₃BC ₆F ₄B(C ₆F ₅) ₃] ^2- (B ₂) as the cocatalyst for both. With MAO as the cocatalyst, ∼600x increases in polyethylene molecular weight are achieved with (μ-CH ₂CH ₂-3,3′){(η ⁵- indenyl)[1-Me ₂Si( ^tBuN)](ZrCl ₂)} ₂ (C2-Zr ₂Cl ₄) and (μ-CH ₂-3,3′) {(η ⁵-indenyl)[1-Me ₂Si( ^tBuN)](ZrCl ₂)} ₂ (C1-Zr ₂Cl ₄) vs mononuclear [1-Me ₂Si(3-ethylindenyl)( ^tBuN)]ZrCl ₂ (Zr ₁Cl ₂). In the ethylene + 1-hexene copolymerization, C1-Zr ₂ enchains 3x more 1-hexene than does C2-Zr ₂ under identical polymerization conditions (B ₂ as cocatalyst). With MAO as the cocatalyst, C2-Zr ₂Cl ₄ enchains 3.5x more, and C1-Zr ₂Cl ₄ 4.2x more, 1-hexene than does Zr ₁Cl ₂. When the polar solvent C ₆H ₅Cl is used as the polymerization medium, dramatic compression in the dispersion of polymerization activities and molecular weights is found. Both homopolymerization and copolymerization results argue that achievable Zr-Zr spatial proximity significantly influences chain transfer rates and selectivity for comonomer enchainment and that such proximity effects are highly cocatalyst and solvent sensitive.

Original language	English
Pages (from-to)	9015-9027
Number of pages	13
Journal	Macromolecules
Volume	38
Issue number	22
DOIs	https://doi.org/10.1021/ma050959c
Publication status	Published - Nov 1 2005

ASJC Scopus subject areas

Organic Chemistry
Polymers and Plastics
Inorganic Chemistry
Materials Chemistry

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title = "Significant proximity and cocatalyst effects in binuclear catalysis for olefin polymerization",

abstract = "We describe here the implementation of methylene-bridged binuclear {"}constrained geometry catalyst{"} (μ-CH 2-3,3′) {(η 5-indenyl)[1-Me 2Si( tBuN)](ZrMe 2)} 2 (Cl-Zr 2) to produce high-M w branched polyethylene. In ethylene homopolymerization, ∼70x increases in molecular weight are achieved with (C1-Zr 2) vs (μ-CH 2CH 2-3,3′){(η 5-indenyl)[1-Me 2Si( tBuN)](ZrMe 2)} 2 (C2-Zr 2) under identical polymerization conditions using (Ph 3C +) 2[1,4-(C 6F 5) 3BC 6F 4B(C 6F 5) 3] 2- (B 2) as the cocatalyst for both. With MAO as the cocatalyst, ∼600x increases in polyethylene molecular weight are achieved with (μ-CH 2CH 2-3,3′){(η 5- indenyl)[1-Me 2Si( tBuN)](ZrCl 2)} 2 (C2-Zr 2Cl 4) and (μ-CH 2-3,3′) {(η 5-indenyl)[1-Me 2Si( tBuN)](ZrCl 2)} 2 (C1-Zr 2Cl 4) vs mononuclear [1-Me 2Si(3-ethylindenyl)( tBuN)]ZrCl 2 (Zr 1Cl 2). In the ethylene + 1-hexene copolymerization, C1-Zr 2 enchains 3x more 1-hexene than does C2-Zr 2 under identical polymerization conditions (B 2 as cocatalyst). With MAO as the cocatalyst, C2-Zr 2Cl 4 enchains 3.5x more, and C1-Zr 2Cl 4 4.2x more, 1-hexene than does Zr 1Cl 2. When the polar solvent C 6H 5Cl is used as the polymerization medium, dramatic compression in the dispersion of polymerization activities and molecular weights is found. Both homopolymerization and copolymerization results argue that achievable Zr-Zr spatial proximity significantly influences chain transfer rates and selectivity for comonomer enchainment and that such proximity effects are highly cocatalyst and solvent sensitive.",

author = "Hongbo Li and Stern, {Charlotte L.} and Marks, {Tobin J.}",

year = "2005",

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doi = "10.1021/ma050959c",

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T1 - Significant proximity and cocatalyst effects in binuclear catalysis for olefin polymerization

AU - Li, Hongbo

AU - Stern, Charlotte L.

AU - Marks, Tobin J.

PY - 2005/11/1

Y1 - 2005/11/1

N2 - We describe here the implementation of methylene-bridged binuclear "constrained geometry catalyst" (μ-CH 2-3,3′) {(η 5-indenyl)[1-Me 2Si( tBuN)](ZrMe 2)} 2 (Cl-Zr 2) to produce high-M w branched polyethylene. In ethylene homopolymerization, ∼70x increases in molecular weight are achieved with (C1-Zr 2) vs (μ-CH 2CH 2-3,3′){(η 5-indenyl)[1-Me 2Si( tBuN)](ZrMe 2)} 2 (C2-Zr 2) under identical polymerization conditions using (Ph 3C +) 2[1,4-(C 6F 5) 3BC 6F 4B(C 6F 5) 3] 2- (B 2) as the cocatalyst for both. With MAO as the cocatalyst, ∼600x increases in polyethylene molecular weight are achieved with (μ-CH 2CH 2-3,3′){(η 5- indenyl)[1-Me 2Si( tBuN)](ZrCl 2)} 2 (C2-Zr 2Cl 4) and (μ-CH 2-3,3′) {(η 5-indenyl)[1-Me 2Si( tBuN)](ZrCl 2)} 2 (C1-Zr 2Cl 4) vs mononuclear [1-Me 2Si(3-ethylindenyl)( tBuN)]ZrCl 2 (Zr 1Cl 2). In the ethylene + 1-hexene copolymerization, C1-Zr 2 enchains 3x more 1-hexene than does C2-Zr 2 under identical polymerization conditions (B 2 as cocatalyst). With MAO as the cocatalyst, C2-Zr 2Cl 4 enchains 3.5x more, and C1-Zr 2Cl 4 4.2x more, 1-hexene than does Zr 1Cl 2. When the polar solvent C 6H 5Cl is used as the polymerization medium, dramatic compression in the dispersion of polymerization activities and molecular weights is found. Both homopolymerization and copolymerization results argue that achievable Zr-Zr spatial proximity significantly influences chain transfer rates and selectivity for comonomer enchainment and that such proximity effects are highly cocatalyst and solvent sensitive.

AB - We describe here the implementation of methylene-bridged binuclear "constrained geometry catalyst" (μ-CH 2-3,3′) {(η 5-indenyl)[1-Me 2Si( tBuN)](ZrMe 2)} 2 (Cl-Zr 2) to produce high-M w branched polyethylene. In ethylene homopolymerization, ∼70x increases in molecular weight are achieved with (C1-Zr 2) vs (μ-CH 2CH 2-3,3′){(η 5-indenyl)[1-Me 2Si( tBuN)](ZrMe 2)} 2 (C2-Zr 2) under identical polymerization conditions using (Ph 3C +) 2[1,4-(C 6F 5) 3BC 6F 4B(C 6F 5) 3] 2- (B 2) as the cocatalyst for both. With MAO as the cocatalyst, ∼600x increases in polyethylene molecular weight are achieved with (μ-CH 2CH 2-3,3′){(η 5- indenyl)[1-Me 2Si( tBuN)](ZrCl 2)} 2 (C2-Zr 2Cl 4) and (μ-CH 2-3,3′) {(η 5-indenyl)[1-Me 2Si( tBuN)](ZrCl 2)} 2 (C1-Zr 2Cl 4) vs mononuclear [1-Me 2Si(3-ethylindenyl)( tBuN)]ZrCl 2 (Zr 1Cl 2). In the ethylene + 1-hexene copolymerization, C1-Zr 2 enchains 3x more 1-hexene than does C2-Zr 2 under identical polymerization conditions (B 2 as cocatalyst). With MAO as the cocatalyst, C2-Zr 2Cl 4 enchains 3.5x more, and C1-Zr 2Cl 4 4.2x more, 1-hexene than does Zr 1Cl 2. When the polar solvent C 6H 5Cl is used as the polymerization medium, dramatic compression in the dispersion of polymerization activities and molecular weights is found. Both homopolymerization and copolymerization results argue that achievable Zr-Zr spatial proximity significantly influences chain transfer rates and selectivity for comonomer enchainment and that such proximity effects are highly cocatalyst and solvent sensitive.

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