Ultra‐Rigid Metallocenes for Highly Iso‐ and Regiospecific Polymerization of Propene: The Search for the Perfect Polypropylene Helix

Schöbel, Alexander; Herdtweck, Eberhardt; Parkinson, Matthew; Rieger, Bernhard

doi:10.1002/chem.201103547

Cited by 53 publications

(69 citation statements)

References 34 publications

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“…Especially the latter aroused huge interest, since this polymer class is not accessible using classic Ziegler-Natta type systems [21,22,23] C1 symmetric complexes based on an ethylene-bridged fluorenyl-indenyl ligand framework (metallocene catalyst M) already demonstrated their high potential in polymer catalysis from elastic to thermoplastic polypropylene [6,24,25,26]. Approaches to isotactic polypropylene are generally conducted using heterogenic Ziegler-Natta type catalysts, although metallocene systems are nowadays available exceeding the heterogeneous ones in terms of stereo-and regioregularity as well as the potential to catalyze ultra-high molecular weights [27,28].…”

Section: Introductionmentioning

confidence: 99%

From elastomers to thermoplasts – Precise control of isotactic propylene structure and properties and the role of different structural elements in its mechanical behaviour

Щербина

Meshchankina

Odarchenko

et al. 2017

Polymer

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Studies of polypropylene with different degrees of isotacticity have shown a way of the rational design of material with predetermined mechanical properties starting from the synthesis stage already-controlled introducement of stereodefects will allow the smooth adjustment of the Young's modulus and elasticity in the range from plastic to elastomer materials. It was also revealed that modern theoretical models of the elasticity can be successfully applied not only for the description of the mechanical behaviour of polymers, but also for better understanding of the mechanism of elasticity in them. While in the low crystalline materials deformation has Gaussian nature, in the materials of the intermediate crystallinity (30-40 %) percolation takes place, and the cross-linking network becomes harder, manifesting the switch to the thermotropic behavior of the material. Simultaneously the divide between cross-and sliplinks becomes substantial, as an extensibility grows sharply.

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Section: Introductionmentioning

confidence: 99%

From elastomers to thermoplasts – Precise control of isotactic propylene structure and properties and the role of different structural elements in its mechanical behaviour

Щербина

Meshchankina

Odarchenko

et al. 2017

Polymer

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“…The calculation of absolute error in the measured LCB content requires separation of the random aspects of the signal from the noise to provide an estimation of the error of the quantitative integral (error in bulk integral can be taken to be negligible). However, often in such cases, more error is introduced by assumptions in the analysis than confidence gained by manipulation, and hence the raw values and example spectra, as presented in this paper, are more informative. That being said, the quantities obtained serve to illustrate general trends and order of magnitude.…”

Section: Methodsmentioning

confidence: 99%

Controlled Synthesis, Characterization, and Flow Properties of Ethylene–Diene Copolymers

Das

Elguweri²,

Jiang

et al. 2019

Macro Reaction Engineering

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/mren.201800071. Ethylene Diene TerpolymersThe flow response of branched entangled resins is dominated by the branching topology of the constituent molecules, a property that is not directly accessible using experimental analytical tools for industrially relevant complex resins. In this paper, the controlled terpolymerization of ethylene, 1,9-decadiene, and either hexene or octene in a continuous stirred tank reactor with a metallocene catalyst, is reported. The synthesized samples are characterized extensively with various analytical tools and their rheological properties are measured with small amplitude oscillatory shear and start-up uniaxial extension experiments. A model is developed for the polymerization process with the mass balance during synthesis providing strong constraints on the rate constants. In silico ensembles of molecules, generated via Monte Carlo sampling, are used to reproduce the experimental results. The computer model allows us to infer the detailed branching structure of the molecules and to predict the optimum range of reactor conditions for this synthesis.

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“…The 13 C NMR analysis of the iPP sample showed the near absence of regio‐errors, and a very low amount of stereo‐errors. Details of the NMR analysis can be found in ref …”

Section: Methodsmentioning

confidence: 99%

“…The present study reports the analysis on the crystallization behavior of an iPP produced by a hafnocene/borate catalyst, nearly free of chain defects . Fast scanning calorimetry (FSC) was used to analyze the crystallization kinetics at rapid cooling, allowing us to evaluate the critical rates of cooling for generation of monoclinic crystals, mesophase, and full vitrification.…”

Section: Introductionmentioning

confidence: 99%

Molecular and Thermal Characterization of a Nearly Perfect Isotactic Poly(propylene)

Tranchida

Mileva

Resconi

et al. 2015

Macro Chemistry & Physics

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The structure formation upon cooling of the quiescent melt of a nearly defect-free isotactic poly(propylene) (iPP) homopolymer is investigated in this study. This iPP, having a molecular weight of 1 × 10 6 g mol −1 and a narrow molecular weight distribution, has been produced with a C2 symmetric hafnocene complex. Information about the crystallization kinetics is collected in a broad range of cooling rates. Standard differential scanning calorimetry is used for cooling rates in the range 3-100 °C min −1 and FSC is employed to analyze the solidifi cation process at cooling rates larger than 100 °C s −1 . The near absence of regio-and stereo-defects allows this iPP to crystallize at signifi cantly high temperatures and to form crystals at cooling rates higher than commonly observed for standard Ziegler-Natta iPP. The data reveal that the iPP homopolymer with close-to-perfect stereo-regularity form crystals at high cooling rates as, e.g., α-nucleated iPP. The defect-free polymer chain allows the formation of relatively thick lamellar crystals which resulted in a relatively high tensile modulus of 2088 ± 8 MPa.

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Ultra‐Rigid Metallocenes for Highly Iso‐ and Regiospecific Polymerization of Propene: The Search for the Perfect Polypropylene Helix

Cited by 53 publications

References 34 publications

From elastomers to thermoplasts – Precise control of isotactic propylene structure and properties and the role of different structural elements in its mechanical behaviour

From elastomers to thermoplasts – Precise control of isotactic propylene structure and properties and the role of different structural elements in its mechanical behaviour

Controlled Synthesis, Characterization, and Flow Properties of Ethylene–Diene Copolymers

Molecular and Thermal Characterization of a Nearly Perfect Isotactic Poly(propylene)

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