Control of Stereoerror Formation with High-Activity “Dual-Side” Zirconocene Catalysts:  A Novel Strategy To Design the Properties of Thermoplastic Elastic Polypropenes

Dietrich, Ulf; Hackmann, Martijn; Rieger, Bernhard; Klinga, and Martti; Leskelä, Markku

doi:10.1021/ja9833220

Cited by 171 publications

(183 citation statements)

References 28 publications

(34 reference statements)

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“…The first approach has the advantage that more than one chain is formed per catalyst center but has the disadvantage that precise control of the number and length of blocks is not easily accomplished. Some examples of nonliving catalysts that produce olefin-based block copolymers include heterogeneous Ziegler-Natta catalysts (7), asymmetric metallocenes (8,9), and the oscillating metallocenes (10). Although living catalysts have the inherent disadvantage that they typically only produce one chain per catalytic active center, they do have the potential for unprecedented levels of control of polymer architecture, including the composition, size, and number of blocks in olefin copolymers (6).…”

Section: Block Polyolefinsmentioning

confidence: 99%

Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Hotta

Cochran

Ruokolainen

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

123

115

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We report the design, synthesis, morphology, phase behavior, and mechanical properties of semicrystalline, polyolefin-based block copolymers. By using living, stereoselective insertion polymerization catalysts, syndiotactic polypropylene-blockpoly(ethylene-co-propylene)-block-syndiotactic polypropylene and isotactic polypropylene-block-regioirregular polypropyleneblock-isotactic polypropylene triblock copolymers were synthesized. The volume fraction and composition of the blocks, as well as the overall size of the macromolecules, were controlled by sequential synthesis of each block of the polymers. These triblock copolymers, with semicrystalline end-blocks and mid-segments with low glass-transition temperatures, show significant potential as thermoplastic elastomers. They have low Young's moduli, large strains at break, and better than 90% elastic recovery at strains of 100% or less. An isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene pentablock copolymer was synthesized that also shows exceptional elastomeric properties. Notably, microphase separation is not necessary in the semicrystalline isotactic polypropylenes to achieve good mechanical performance, unlike commercial styrenic thermoplastic elastomers.block copolymer ͉ polypropylene T he applications of a polymer are largely determined by its chemical, physical, and mechanical properties. These properties are in turn determined by polymer morphology, which is dictated by polymer structure and composition. Thermoplastic elastomers are a classic example where polymer architecture engenders unique properties. Block copolymers that contain at least two blocks that are hard at room temperature, separated by blocks with a glass transition temperature (T g ) below room temperature, typically exhibit elastomeric properties if the low T g block volume is large (1-5). The most well known elastomers of this type are the polystyrene (PS)-block (b)-polybutadiene-b-PS triblock copolymers, sold commercially by Kraton Polymers. Such materials normally possess a microphase-separated morphology in which 10-nm-scale domains of the hard blocks (e.g., PS) are embedded as spheres or cylinders within a continuous phase of the low T g soft blocks. The hard domains serve as thermally reversible crosslinks that at room temperature produce high levels of recoverable elasticity in the soft phase.Sequence control of a synthetic polymer is most easily accomplished by using a synthetic technique that allows the sequential addition of one or more monomers to the macromolecule in a chain growth process without spontaneous termination. These techniques are collectively called living polymerizations, and despite many successes over the last half century, their further development remains one of the most important frontiers in polymer science. In the case of the Kraton triblock copolymers, a living anionic polymerization process is used to synthesize the materials. Because approximately t...

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Section: Block Polyolefinsmentioning

confidence: 99%

Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Hotta

Cochran

Ruokolainen

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

123

115

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“…43 Methylaluminoxane and triisobutylaluminum were purchased from Witco (Greenwich, USA) and toluene for the polymerization reactions from Merck (Darmstadt, Germany). The ethylene-bridged zirconocene has been prepared as described in.…”

Section: Experimental Polymerization Experimentsmentioning

confidence: 99%

“…The ethylene-bridged zirconocene has been prepared as described in. 43 The polymerization reactions were performed in a 0.5-L Büchi steel reactor at constant pressure and temperature. The autoclave was charged with 200 mL toluene and with MAO cocatalyst and zirconocene dichloride.…”

Section: Experimental Polymerization Experimentsmentioning

confidence: 99%

“…27,[29][30][31][32][33][34] Using specific metallocene catalysts at varying polymerization conditions, such as monomer concentration temperature, nature of cocatalyst, 1 low isotactic polypropylenes can be obtained containing different amounts and combinations of stereoerrors leading to high molecular weight atactic polypropylene, 29,[35][36][37] polypropylenes with an intermediate isotactic-atactic microstructure, 6,29,38-40 stereoblock isotactic-atactic polypropylenes 7,8,12,14,41 or stereoblock isotactic-hemiisotactic polypropylenes. 42 Beside those, a new type of high molecular weight, low isotactic polypropylene has been synthesized by Rieger et al [43][44][45] Due to the random incorporation of stereoerrors, these polypropylenes contain statistically distributed, isotactic sequences. 31 Although the isotactic sequences are expected to be short, these polymers reveal a crystalline phase.…”

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confidence: 99%

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Nucleation and Crystallization of Low Isotatic Polypropylenes with Statistically Distributed Stereoerrors

et al. 2009

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The time dependent crystallization of a low isotactic polypropylene with statistically incorporated stereoerrors was investigated by the combination of differential scanning calorimetry (DSC), wideangle X-ray scattering (WAXS) and scanning force microscopy (SFM). Owing to Scanning force microscopy (SFM) and WAXS experiments the crystallization of the sample in mixed =-form aggregates can be proposed. The nucleation and growth processes of crystallization in thin polypropylene films in real time were visualized with nanometer resolution by using SFM at variable temperature. During the isothermal crystallization from the melt initially crystals of the -form were developed. These lamellae act as nuclei for the further crystallization of -and mixed =-lamellae, which can be observed at longer crystallization times. Time dependent SFM and WAXS experiments showed that due to the low amount of crystallizable, regular sequences and its statistical distribution only slow crystallization rates can be observed. These results form the basis for a better understanding of the crystallization of low crystallinity polypropylenes. The investigations clearly show that the distribution of the regular isotactic segments influences the crystallization properties of propene based TEP's. This opens the possibility to tailor not only the mechanical but also the thermal properties of elastomeric polypropylenes by changing the polymer microstructure.

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“…Therefore, isotactic-atactic stereoblock polypropylenes have been widely used as adhesives, sealants and coatings, additives for building top grade high way and so on [1,2]. Isotactic-atactic stereoblock polypropylenes are typically synthesized by the asymmetric homogeneous metallocene catalysts, such as rac-Et[(Me 4 -Cp](Ind)TiCl 2 , Me 2 Si[(Me-Ind)(Ind)]ZrCl 2 , rac-[Et(Flu)(2-Me-Flu)]ZrCl 2 and rac-[Et(Flu)(2-Me-benInd)]ZrCl 2 [3][4][5][6]. However, the microstructure and property of block polypropylenes heavily depends on structure of catalysts symmetry, co-catalyst employed and polymerization condi-tions [7,8].…”

Section: Introductionmentioning

confidence: 99%

Propylene Polymerization Catalyzed by rac-Et(Ind)2ZrCl2/Cp2ZrCl2 in the Presence of ZnEt2

Xiao

Wang

Liu

et al. 2009

Designed Monomers and Polymers

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Polypropylene was synthesized using binary metallocene catalysts, rac-ethylenebis-(1-η5-indenyl)-zirconium dichloride (rac-Et(Ind) 2 ZrCl 2 : Cata A) and zirconocene dichloride (Cp 2 ZrCl 2 : Cata B), in the presence of ZnEt 2 . The results indicated that ZnEt 2 was an effective agent in modulating isotactivity of polypropylene. Moreover, it was found that the [mmmm] pentad value of polypropylene prepared in the presence of diethyl zinc decreased to 84, and the new peaks of [rmmr] and [rmrr + mmrm] appeared, in contrast to the peaks from polyproplene obtained in the absence of diethyl zinc. Therefore, the possible reason was the occurrence of chain-shuttling polymerization in the CataA/CataB/ZnEt 2 catalyst system.

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Control of Stereoerror Formation with High-Activity “Dual-Side” Zirconocene Catalysts: A Novel Strategy To Design the Properties of Thermoplastic Elastic Polypropenes

Cited by 171 publications

References 28 publications

Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Nucleation and Crystallization of Low Isotatic Polypropylenes with Statistically Distributed Stereoerrors

Propylene Polymerization Catalyzed by rac-Et(Ind)2ZrCl2/Cp2ZrCl2 in the Presence of ZnEt2

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