2018
DOI: 10.1021/acs.macromol.7b02679
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High-Melting, Elastic Polypropylene: A One-Pot, One-Catalyst Strategy toward Propylene-Based Thermoplastic Elastomers

Abstract: This contribution provides the simple one-pot, one-catalyst synthesis of high-melting (T m ∼ 140 °C), high-molecular-weight, elastic polypropylene ( e PP) offering an excellent reversible deformation behavior. The produced propylene-based thermoplastic elastomers contain of i PP– a PP block structures embedded in an amorphous polypropylene matrix which is enabled by the variable stereoselective behavior of ethylene-bridged fluorenylindenyl (EBFI) ansa-metallocene complexes. For the tailored synthesis of these… Show more

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Cited by 12 publications
(9 citation statements)
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“…The increase in temperature resulted in a greater degree of misinsertions; thus, the syndiotacticity decreased (Figures S28−S31). This behavior was consistent not only with an increased back-skip mechanism at an increasing temperature 37 but also through a general loss of stereocontrol. A difference in stereocontrol was observed when the central metal atom in Ia was changed to Hf.…”
Section: ■ Results and Discussionsupporting
confidence: 76%
“…The increase in temperature resulted in a greater degree of misinsertions; thus, the syndiotacticity decreased (Figures S28−S31). This behavior was consistent not only with an increased back-skip mechanism at an increasing temperature 37 but also through a general loss of stereocontrol. A difference in stereocontrol was observed when the central metal atom in Ia was changed to Hf.…”
Section: ■ Results and Discussionsupporting
confidence: 76%
“…Today, zirconocene complexes are commonly stated to be the most active ones in the polymerization of propene, whereupon examples are known in which suitably activated hafnocenes exhibit comparably high activities. This is contrary to previous reports assigning the lower activities of Hf to lower chain propagation rates as a result of a stronger metal–carbon bond. ,, In contrast, the catalytic activity of titanocene complexes generally suffers from catalyst deactivation due to reductive processes. ,, The exchange from Zr to Hf becomes particularly important regarding the molecular weights of the respective polymers. Significantly higher molar masses for the polymers of the hafnocene compared to the zirconocene analog are herein observed for C 1 -, C 2 - and C s -symmetric ansa -metallocene complexes and have established the so-called “hafnium effect”. ,,,, In this context, a stronger Hf–C versus Zr–C bond has served as most plausible explanation for more than three decades. ,,, However, the impact of a thermodynamically more stable bond on the molecular weight of the produced polymer chains is not directly related since kinetics finally determine the averaged chain lengths of a polymer. Accordingly, it is the rate ratio of chain propagation and chain release that gives the respective molecular weights and evokes the elementary question how the M–C bond strength favors the propagation relative to the chain release reactions.…”
Section: Introductionmentioning
confidence: 83%
“…Significantly higher molar masses for the polymers of the hafnocene compared to the zirconocene analog are herein observed for C 1 -, C 2 -and C ssymmetric ansa-metallocene complexes and have established the so-called "hafnium effect". 12,14,18,21,22 In this context, a stronger Hf−C versus Zr−C bond has served as most plausible explanation for more than three decades. 8,12,18,23 However, the impact of a thermodynamically more stable bond on the molecular weight of the produced polymer chains is not directly related since kinetics finally determine the averaged chain lengths of a polymer.…”
Section: ■ Introductionmentioning
confidence: 99%
“…Among them, homogeneous vanadium catalysts are of great importance. These catalytic systems are derived from a combination of vanadium compounds (e.g., VCl 4 , VOCl 3 , VO(OR) 3 , V(acac) 3 , R = alkyl group, acac = acetylacetonate) and alkyl aluminum halide (typically Et 2 AlCl) or aluminum hydride derivatives, and a Lewis base (e.g., anisole). 29−34 Herein, we report the terpolymerization of ethylene with propylene and ENB catalyzed by known imido vanadium(IV) complexes, 35,36 differing in the ligand substitution, in combination with Et 2 AlCl and Cl 3 CCO 2 Et (ETA).…”
Section: Introductionmentioning
confidence: 99%