La copolymerisation du systeme binaire acrylonitrile-methylmethacrylate a l'aide des promoteurs du type soluble ziegler-natta constitues par le complexe: dichlorure du biscyclopentadienyl-titane-triethyle aluminium

Simionescu, C. I.; Asandei, N.; Benedek, István; Ungurenasu, Cezar

doi:10.1016/0014-3057(69)90074-3

Cited by 15 publications

(4 citation statements)

References 3 publications

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“…On the other hand, early metal-catalyzed homopolymerization of polar vinyl monomers has been highly successful. ,,, Four decades ago, conventional Ziegler−Natta-type catalysts, including TiCl 4 /AlR 3 , and Cp 2 TiCl 2 /AlEt 3 , were already employed for syndiospecific polymerization of methyl methacrylate (MMA) at low temperatures (−28 to −78 °C) and for copolymerization of MMA with acrylonitrile (AN) at high temperatures (40−80 °C), respectively, despite the fact that active species, polymerization mechanism, and degree of polymerization control were unknown. Ballard and van Lienden reported in 1972 the use of metal tetrabenzyl complexes, such as Zr(CH 2 Ph) 4 , to polymerize MMA in toluene via a postulated coordinative anionic polymerization .…”

Section: Introductionmentioning

confidence: 99%

Coordination Polymerization of Polar Vinyl Monomers by Single-Site Metal Catalysts

2009

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Section: Introductionmentioning

confidence: 99%

Coordination Polymerization of Polar Vinyl Monomers by Single-Site Metal Catalysts

2009

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“…As compared to the intensively investigated MMA polymerization by zirconocenes, MMA polymerization by titanocenes drew much less attention. Titanocene dichloride Cp 2 TiCl 2 (plus excess AlEt 3 ) was used to copolymerize MMA and acrylonitrile with a proposed ionic coordination mechanism . Farnham and Hertler used Cp 2 TiCl[OC(OMe)CMe 2 ] to polymerize MMA, affording PMMA with polydispersity index (PDI) ranging from 3.14 to 4.30 .…”

Section: Introductionmentioning

confidence: 99%

Living and Syndioselective Polymerization of Methacrylates by Constrained Geometry Titanium Alkyl and Enolate Complexes

2004

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This paper reports the homopolymerization and block copolymerization of methacrylates by the cationic titanium methyl complex, CGCTiMe + MeB(C6F5)3 -(1, CGC ) Me2Si(Me4C5)(t-BuN)), as well as the synthesis and methyl methacrylate (MMA) polymerization of three new neutral and cationic CGC Ti ester enolate complexes. Unlike the isostructural, cationic CGC Zr methyl complex, which is inactive for polymerization of MMA, CGC Ti methyl complex 1 effects living polymerizations of MMA and BMA (BMA ) n-butyl methacrylate) at ambient temperature, producing syndiotactic PMMA ([rr] ) 82%, Pr ) 0.90) and PBMA ([rr] ) 89%, Pr ) 0.95). Sequential copolymerization using 1 and starting from either MMA or BMA produces the well-defined, syndiotactic diblock copolymer PMMA-b-PBMA with narrow molecular weight distribution (Mw/Mn ) 1.08). On the other hand, copolymerizing MMA and BMA simultaneously affords the homogeneous random copolymer PMMA-co-PBMA. Two neutral CGC Ti ester enolate complexes, CGCTiCl[OC(O i Pr)dCMe2] (2) and CGCTiMe[OC(O i Pr)dCMe2] (4), have been synthesized, and the molecular structure of 4 has been determined by X-ray crystallography. The reaction of 4 and B(C6F5)3‚THF (THF ) tetrahydrofuran) in methylene chloride readily generates the cationic CGC Ti ester enolate complex, CGCTi + (THF)[OC(O i Pr)dCMe2] [MeB(C6F5)3] -(5). All three CGC Ti ester enolate complexes have been investigated for MMA polymerization; of particular interest are the polymer characteristics (molecular weight, molecular weight distribution, and syndiotacticity) of the PMMA formed by 5, which are remarkably similar to those of the PMMA by 1, suggesting that the cationic ester enolate 5 is an appropriate model for the propagating species involved in the MMA polymerization by the alkyl cation 1. The microstructures of PMMA have been analyzed at the pentad level, and the polymerization mechanism has also been discussed.

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“…The results from Table 3 shows that the chromium complex 1 has much high activity than the metallocene catalysts reported by Natta and Simionescu [27,28] . Activated by aluminum cocatalyst, chromium complex 1 can form a cationic structure that has a similar electronic distribution as that of Natta-type metallocene catalysts to promote the polymerization of MMA.…”

Section: Catalytic Polymerizationmentioning

confidence: 83%

Synthesis, characterization and application of a novel carbon bridged half-metallocene chromium catalyst for methyl methacrylate polymerization

Cheng

Gong

Wang

et al. 2014

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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A new carbon bridged cyclopentadienyl chromium complex of the type [(C 5 H 4 )C(CH 3 ) 2 CH 2 (C 5 H 4 N)]CrCl 2 was prepared by treatment of CrCl 3 •(THF) 3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups. The chromium complex was characterized by 1 H NMR and elemental analysis(EA), and the crystal structure was determined by X-ray diffraction analysis. Activated by Al(i-Bu) 3 , the chromium complex displayed a very high activity for methyl methacrylate (MMA) polymerization. After 24 hours,more than 95.5% MMA was converted to polymethyl methacrylate (PMMA) with a viscosity average molecular weight (W η ) of 416000 g•mol 1 at 60 ℃ for MMA/ Al(i-Bu) 3 /chromium catalyst molar ratio of up to 2000:20:1. Effects of temperature, molar ratios of MMA/catalyst and catalyst/ cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.

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La copolymerisation du systeme binaire acrylonitrile-methylmethacrylate a l'aide des promoteurs du type soluble ziegler-natta constitues par le complexe: dichlorure du biscyclopentadienyl-titane-triethyle aluminium

Cited by 15 publications

References 3 publications

Coordination Polymerization of Polar Vinyl Monomers by Single-Site Metal Catalysts

Coordination Polymerization of Polar Vinyl Monomers by Single-Site Metal Catalysts

Living and Syndioselective Polymerization of Methacrylates by Constrained Geometry Titanium Alkyl and Enolate Complexes

Synthesis, characterization and application of a novel carbon bridged half-metallocene chromium catalyst for methyl methacrylate polymerization

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