Elastomeric polypropylenes from alumina-supported tetraalkyl Group IVB catalysts. 1. Synthesis and properties of high molecular weight stereoblock homopolymers

Collette, John W.; Tullock, C. W.; MacDonald, Robert N.; Buck, Warren H.; Su, Aaron C. L.; Harrell, J. R.; Mülhaupt, Rolf; Anderson, B. C.

doi:10.1021/ma00200a006

Cited by 122 publications

(134 citation statements)

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“…[87,88] The cocrystallization was elucidated as a function of poly(propylene) microstructures and reactor blend compositions. With Chien's CH 3 CH(Me 4 Cp)(Ind)TiCl 2 /MAO, [89] Waymouth's oszillating non-bridged (2-Ph-Ind) 2 ZrCl 2 /MAO, [90] and Rieger's ''dual side'' metallocene catalysts [91,92] it became possible to produce high molecular weight stereoblock poly(propylene) with much narrower molecular weight distributions and without formation of isotactic poly(propylene) as by-products.…”

Section: Stereoblock Poly(propylene) and Elastomeric Poly(propylene)mentioning

confidence: 99%

Catalytic Polymerization and Post Polymerization Catalysis Fifty Years After the Discovery of Ziegler's Catalysts

Mülhaupt

2003

Macro Chemistry & Physics

276

193

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During the 1950's the discoveries of Ziegler's organometallic catalyst systems and Natta's stereoselective olefin polymerization set the stage for extraordinary progress in polymer science and technology. Today advanced catalyst systems are available for catalytic carbon carbon bond formation by means of polyinsertion, metathesis, coupling reactions, and controlled radical polymerization. Modern catalytic olefin polymerization processes and polyolefins are environmentally friendly and meet the demands of a sustainable development. The architectures of homo‐ and copolymers based upon olefin, cycloolefin, diene, styrene and arene feed stocks are tailored as a function of single site catalysts' ligand frameworks. Polymer properties are varied over a very wide range, e.g., liquid/solid, rigid/soft, crystalline/amorphous/rubbery, permeable/impermeable, opaque/transparent, moldable/thermosetting, insulating/conducting. Advanced polymerization reaction engineering, copolymerization processes, reactor granule and reactor blend technologies, tailor‐made single site catalysts, catalyst blends and tandem catalysis improve property profiles, stability, morphology, and melt processing. Tuned cycloolefin polymers are new functional materials for electronic applications. Catalytic chain transfer (CCT) and atom transfer polymerization (ATRP) produce a variety of new functional polymers, reactive oligomers, and block copolymers. Aqueous polyolefin emulsions are obtained when catalytic olefin polymerization is performed in nanodroplets of catalyst miniemulsions. The scope of catalytic polymerization and post polymerization catalysis is progressing well beyond the frontiers of commodity polyolefin manufacturing. Advanced catalytic processes produce polar polymers such as polyethers, polyketones, polyesters, polycarbonates, polyamides, polyaramids, and polyimides. The new phosgene free polycarbonate syntheses are based upon the palladium catalyzed oxidative carbonylation. This overview highlights history, recent progress and modern trends in catalytic polymerization and catalytic polymer modification illustrated by selected examples.

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Section: Stereoblock Poly(propylene) and Elastomeric Poly(propylene)mentioning

confidence: 99%

Catalytic Polymerization and Post Polymerization Catalysis Fifty Years After the Discovery of Ziegler's Catalysts

Mülhaupt

2003

Macro Chemistry & Physics

276

193

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“…Silica is a classic choice, generating monosiloxy, bissiloxy and in some cases trissiloxy surface complexes which can be used as catalyst in several reactions (hydrogenation, polymerization, metathesis) [2,3]. In many cases however, other supports such as alumina must be used to yield active surface species [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…Grafting of [Zr(CH 2 tBu) 4 ] on alumina provides an efficient polymerization catalyst, while the same species grafted on silica is inactive [4][5][6][7][8]. By treatment under hydrogen, the grafted Zr-alkyl is a precursor for a surface zirconium hydride which is active in the hydrogenolysis of butane [9].…”

Section: Introductionmentioning

confidence: 99%

Gamma-alumina: An Active Support to Obtain Immobilized Electron Poor Zr Complexes

et al. 2008

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By grafting well-defined metallic complexes on a solid support, surface organometallic chemistry provides a bridge between homogeneous and heterogeneous catalysis. This innovative approach has already proven its efficiency for several reactions: polymerization, olefin and alkane metathesis… However several fundamental questions remain open on the chemical role of the oxide surface, on the grafting mechanism and on the reactivity of the grafted complex. Is a single well-defined surface/metal/ligand complex formed? Is the solid surface just an inert support, or does it play an active chemical role? We combine on the one hand reactivity and spectroscopic experiments with on the other hand total energy calculations and spectra simulations (NMR, IR) in order to propose insights for these open questions, using the example of [Zr(CH 2 tBu) 4 ] complex grafted on partially dehydroxylated gamma-alumina. A molecular level approach to the grafting mechanism is proposed. Alumina plays a dual role, both as support and Lewis acid co-catalyst. The hydroxyl groups permit the covalent grafting through Al-O-Zr linkages, while the neighboring Al Lewis sites allow the formation of an ion pair, by transfer of an alkyl ligand from the Zr toward the Al. The formed cationic Zr center shows an enhanced electrophilic character. The mechanism of the formation of the Zr hydride supported on alumina, upon treatment under H 2 gas is described, with the formation of a mixture of mono-hydride (Zr + -H; Al --CH 2 tBu) and bis-hydride (Zr + -H; Al --H). This Zr hydride supported on alumina is active for butane hydrogenolysis. A mechanism with reasonable energy barriers is proposed, the rate limiting step being the C-C scission.

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“…Collette et al subsequently reported improved catalysts for the synthesis of poly(propylene) with elastomeric properties based on the use of Zr and Ti alkyls on alumina supports 3,4) , and then Chien et al reported the synthesis of elastomeric poly(propylene) using a stereorigid titanocene catalyst and its dimethyl derivative [5][6][7][8][9] . It was proposed that the polymerization occurs alternately at aspecific and isospecific coordination sites to give a stereoblock structure 6) .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of high-molecular-weight elastomeric poly(propylene) with half-titanocene/MAO catalyst

Xie¹,

Wu²,

Lin³

1999

Macromol. Rapid Commun.

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SUMMARY: A novel catalyst precursor, (g 5 -pentamethylcyclopentadienyl)titanium triallyloxide (Cp*Ti(OCH 2 1CH2CH 2 ) 3 ), was prepared and employed in a study of propylene polymerization in the presence of methylaluminoxane (MAO). This work has revealed that the half-titanocene catalyst is desirable for the production of elastomeric poly(propylene) with high molecular weight (M -w = 8-69610 4 ) as well as in good yields under typical polymerization conditions.

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Elastomeric polypropylenes from alumina-supported tetraalkyl Group IVB catalysts. 1. Synthesis and properties of high molecular weight stereoblock homopolymers

Cited by 122 publications

References 2 publications

Catalytic Polymerization and Post Polymerization Catalysis Fifty Years After the Discovery of Ziegler's Catalysts

Catalytic Polymerization and Post Polymerization Catalysis Fifty Years After the Discovery of Ziegler's Catalysts

Gamma-alumina: An Active Support to Obtain Immobilized Electron Poor Zr Complexes

Synthesis of high-molecular-weight elastomeric poly(propylene) with half-titanocene/MAO catalyst

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