Highly branched polyethylene oligomers via group IV-catalysed polymerization in very nonpolar media

Gao, Yanshan; Chen, Jiazhen; Wang, Yang; Pickens, David; Motta, Alessandro; Wang, Q. Jane; Chung, Yip Wah; Lohr, Tracy L.; Marks, Tobin J.

doi:10.1038/s41929-018-0224-0

Cited by 75 publications

(73 citation statements)

References 44 publications

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“…Thep olymerization medium/solvent influences the catalytic and polymer properties. [42,43] Thep olymerization of complex 6 was investigated using various solvents.P olymerizations performed in hexanes,t oluene,c hlorobenzene (PhCl), and dichloromethane (DCM) showed similar activities to the gas-phase polymerization ( Table 2, entries 7-10 vs. entry 2), producing ultra-high-molecular-weight polyethylenes (UHMWPE) with high melting points.I nterestingly, the molecular weight of the polymers increased in the order of:hexanes < toluene < PhCl < DCM, along with decreased branching densities.This trend may be related to the ability of the solvent to coordinate with the metal center, which suppressed both chain transfer and chain walking associated with b-hydride elimination. Theu se of highly coordinating solvents,s uch as ether (Et 2 O) and tetrahydrofuran (THF), can significantly decrease the polymerization activity and polyethylene molecular weight as ar esult of competitive binding versus the ethylene monomer ( Table 2, entries 11,12).…”

Section: Methodsmentioning

confidence: 99%

A Self‐Supporting Strategy for Gas‐Phase and Slurry‐Phase Ethylene Polymerization using Late‐Transition‐Metal Catalysts

Dai

Chen

2020

Angew Chem Int Ed

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The polyolefin industry is dominated by gas‐phase and slurry‐phase polymerization using heterogeneous catalysts. In contrast, academic research is focused on homogeneous systems, especially for late‐transition‐metal catalysts. The heterogenization of homogeneous catalysts is a general strategy to provide catalyst solutions for existing industrial polyolefin synthesis. Herein, we report an alternative, potentially general strategy for using homogeneous late‐transition‐metal catalysts in gas‐phase and slurry‐phase polymerization. In this self‐supporting strategy, catalysts with moderate chain‐walking capabilities produced porous polymer supports during gas‐phase ethylene polymerization. Chain walking, in which the metal center can move up and down the polymer chain during polymerization, ensures that the metal center can travel along the polymer chain to find suitable sites for ethylene enchainment. This strategy enables simple heterogenization of catalysts on solid supports for slurry‐phase polymerization. Most importantly, various branched ultra‐high‐molecular‐weight polyethylenes can be prepared under various polymerization conditions with proper catalyst selection.

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Section: Methodsmentioning

confidence: 99%

A Self‐Supporting Strategy for Gas‐Phase and Slurry‐Phase Ethylene Polymerization using Late‐Transition‐Metal Catalysts

Dai

Chen

2020

Angew Chem Int Ed

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“…or more than half a century, transition metal-catalyzed olefin polymerization has been a global topic of intense research [1][2][3][4] . The metal nickel entered this field as a poison.…”

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confidence: 99%

A simple and versatile nickel platform for the generation of branched high molecular weight polyolefins

2020

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The development of high-performance transition metal catalysts has long been a major driving force in academic and industrial polyolefin research. Late transition metal-based olefin polymerization catalysts possess many unique properties, such as the ability to generate variously branched polyolefins using only ethylene as the feedstock and the capability of incorporating polar functionalized comonomers without protecting agents. Here we report the synthesis and (co)polymerization studies of a simple but extremely versatile α-iminoketone nickel system. This type of catalyst is easy to synthesize and modify, and it is thermally stable and highly active during ethylene polymerization without the addition of any cocatalysts. Despite the sterically open nature, these catalysts can generate branched Ultra-High-Molecular-Weight polyethylene and copolymerize ethylene with a series of polar comonomers. The versatility of this platform has been further demonstrated through the synthesis of a dinuclear nickel catalyst and the installation of an anchor for catalyst heterogenization.

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“…These values are much higher than the minimum molecular weight (that is, 25 000 g mol −1 ) required for good mechanical and physical features in commercialized polymers . The polymerization can be carried out in industrially preferred saturated hydrocarbon solvents while maintaining good properties (Table , sample 13). After polymerization, the remaining comonomers can be recovered at high rates (>95 %) through simple filtration (Supporting Information, Table S1).…”

Section: Resultsmentioning

confidence: 99%

Polar‐Functionalized, Crosslinkable, Self‐Healing, and Photoresponsive Polyolefins

2019

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The nonpolar nature of polyolefins is one of their biggest limitations. Now, an efficient route to generate polar‐functionalized, crosslinkable, self‐healing, photoresponsive polyolefins with thermoplastic, elastomeric, and thermosetting properties is reported. Tunable amounts of carboxylic acid and a cyclic comonomer are installed onto polyolefins by palladium‐catalyzed terpolymerization reactions. The incorporated carboxylic acid unit can alter the surface properties of polyolefins. The subsequently introduced Fe3+/citric acid combination induces dynamic crosslinking and enables self‐healing. Under UV light irradiation, citric acid reduces Fe3+ to Fe2+ and decreases the crosslinking density. The Fe2+ moiety can be easily oxidized back to Fe3+, making the process reversible at the expense of citric acid. The incorporated cyclic comonomer modulates the crystallinity of polyolefins, provides elastic properties, and installs carbon–carbon double bonds for sulfur‐induced vulcanization.

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Highly branched polyethylene oligomers via group IV-catalysed polymerization in very nonpolar media

Cited by 75 publications

References 44 publications

A Self‐Supporting Strategy for Gas‐Phase and Slurry‐Phase Ethylene Polymerization using Late‐Transition‐Metal Catalysts

A Self‐Supporting Strategy for Gas‐Phase and Slurry‐Phase Ethylene Polymerization using Late‐Transition‐Metal Catalysts

A simple and versatile nickel platform for the generation of branched high molecular weight polyolefins

Polar‐Functionalized, Crosslinkable, Self‐Healing, and Photoresponsive Polyolefins

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