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 | |
| Publication status | Published - Nov 1 2005 |
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ASJC Scopus subject areas
- Materials Chemistry
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Significant proximity and cocatalyst effects in binuclear catalysis for olefin polymerization. / Li, Hongbo; Stern, Charlotte L.; Marks, Tobin J.
In: Macromolecules, Vol. 38, No. 22, 01.11.2005, p. 9015-9027.Research output: Contribution to journal › Article
}
TY - JOUR
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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U2 - 10.1021/ma050959c
DO - 10.1021/ma050959c
M3 - Article
AN - SCOPUS:27744442206
VL - 38
SP - 9015
EP - 9027
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 22
ER -