Coordinative Chain Transfer Polymerization of Butadiene with Functionalized Aluminum Reagents

Göttker‐Schnetmann, Inigo; Kenyon, Philip; Mecking, Stefan

doi:10.1002/anie.201909843

Cited by 29 publications

(13 citation statements)

References 28 publications

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“…Mecking et al reported on functionalized aluminum alkyls, which are capable of selective polymerization via coordinative chain transfer. 89 In this regard, functionalized and easily accessible mixed 77 that a large number (~90%) of aluminum-bound carbazole groups are able to initiate polymerization while retaining high (90-95%) cis-1,4 butadiene.…”

Section: E Nickel Catalystsmentioning

confidence: 99%

Butadiene Rubber: Synthesis, Microstructure, and Role of Catalysts

Kumar

Mohanty

Gupta

2021

Rubber Chemistry and Technology

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Butadiene rubber (BR) is one of the most useful and second most produced rubber worldwide. Polymerization of 1,3-butadiene (BD) is a highly stereospecific reaction that offers a wide variety of BR with different microstructures and influences the fundamental properties of the rubber. Since the first successful polymerization of conjugated diene using the Ziegler–Natta–based catalyst (TiCl4 or TiCl3 with aluminum alkyls) in 1954, the research on producing synthetic rubber with an appropriate catalyst system has been accelerated. Subsequently, various research groups are actively engaged in designing active catalyst systems based on a suitable combination of transition metal complexes with alkyl-aluminum and successfully using them in BD polymerization. Although various scientific inventions have proven their significance for the production of high-quality BR, with the rising demands in improving the quality of the product, research on developing new catalyst systems with enhanced catalytic activity and high stereoselectivity is still in progress. The present review focuses on the synthesis of BR using various transition metal catalysts and discusses their microstructures. The catalysts based on new-generation metal complexes with phosphorus, nitrogen, and oxygen donor ligands (e.g., phosphines, imines, 1,10-phenanthroline, and imino-pyridines) have been introduced. The role that catalysts play in the production of BR with different microstructures (i.e., high-cis, high-trans or low-cis, low-trans polybutadiene) has also been described. The combination of catalyst (transition metal complex) and suitable co-catalyst (alkyl-aluminum) is the major factor influencing the reaction and microstructure of the resulting polymer. This report focuses on the effect of transition metal catalysts (i.e., lithium [Li], titanium [Ti], zirconium [Zr], iron [Fe], cobalt [Co], nickel [Ni], and neodymium [Nd]) on the activity and stereoselectivity of polymers such as 1,4-cis-, 1,4-trans-, and 1,2-vinyl-polybutadiene.

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Section: E Nickel Catalystsmentioning

confidence: 99%

Butadiene Rubber: Synthesis, Microstructure, and Role of Catalysts

Kumar

Mohanty

Gupta

2021

Rubber Chemistry and Technology

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“…Sita et al also reported CCTP reactions of propylene to afford atactic PP with tunable molecular weights (although the M n for i PP was only 1000–2000) and very narrow Poisson molecular weight distributions (PDI < 1.2). − ,, The absolute cost of CCTP is lower than that of ordinary living coordinative polymerization (LCP): CCTP circumvents the critical “one polymer chain per metal center” of LCP, which has proven to be an insurmountable liability for the large-scale production of precision polyolefins. In principle, CCTP offers great potential for large-scale production of low-molecular-weight, end-functionalized polyolefins − and, more importantly, high-molecular-weight, well-controlled linear block copolymers.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Well-Controlled Isotactic Polypropylene-Based Block Copolymers with Superior Physical Performance via Efficient Coordinative Chain Transfer Polymerization

Gao

Chen

et al. 2022

Macromolecules

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The synthesis of isotactic polypropylene (iPP)-based block copolymers by means of controlled isoselective polymerization of propylene with high turnover frequencies is an ongoing challenge in industry and academia. Herein, we report a new strategy for reversible coordinative chain transfer polymerization of propylene and propylene−ethylene with a pyridylamido hafnium/[Ph 3 C][B(C 6 F 5 ) 4 ] catalyst system and iBu 3 Al as a chain transfer agent under conditions that were optimized so that the rate constants for chain transfer and chain propagation were similar (k p ≈ k ct ). Using this new strategy, we could obtain iPP-b-poly(ethylene-co-propylene) and iPP-b-poly(ethylene-co-propylene)-b-iPP block copolymers with controlled molecular weights, hard/soft block ratios, and compositions via a continuous-monomer-feeding approach like that used in living polymerization systems. The polymerization reactions produced uniform block copolymers with previously inaccessible microstructures. The copolymers have both a semicrystalline iPP block ([mmmm] > 99%, melting temperature > 155 °C) and soft ethylene−propylene copolymer blocks (glass transition temperature < −30 °C), with tunable high molecular weights (∼210 kDa) and Schulz−Flory distributions (PDI < 2.5). These promising block copolymers possess dramatically improved tensile properties (30−50-fold increase in elongation at break) relative to those of the iPP homopolymer, whereas the yield strength and strength at break were similar to those of the iPP homopolymer. By tuning the block composition and hard/soft block ratio, we could obtain block copolymers ranging from ductile elastomers to tough plastics. Our new strategy not only sheds significant light on olefin CCTP but also has great potential utility for the industrial production of high-performance polyolefin materials.

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“…Within conventional free-radical polymerisation of vinyl monomers the telogen is often referred to as a chain-transfer agent (CTA) and the structure, chemistry and concentration of the chosen CTA has a significant influence on polymerisation outcomes; 21 a range of CTA strategies have been reported including addition of compounds such as thiols, coordinative chain transfer, 22 the use of cobalt-derived catalytic chain transfer. 23 Strictly speaking, the CTA is only considered a telogen if very short chains are formed, comprising chain-ends that are derived solely from the CTA, 24 and initiator residues are not found within the oligomeric product.…”

Section: Introductionmentioning

confidence: 99%