A rigid–flexible double-layer steric strategy promoting ethylene polymerization and copolymerization in alkane solvents

Lu, Weiqing; Fan, Wenbing; Dai, Shengyu

doi:10.1039/d2qi01895k

Cited by 20 publications

(10 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is known that the ratio between the chain growth rate and the chain walking rate is responsible for the microstructure of the polyethylene materials in α‐diimine nickel/palladium catalyzed ethylene polymerization, which ultimately determines their mechanical properties. [ 13,16,20,39‐41 ] The mechanical properties of the resultant semi‐crystalline polyethylenes were evaluated by tensile testing (Figure 4, Table S1). The branched polyethylenes generated by Ni1 — 3 exhibited high stress at break values (12.0—33.1 MPa) and high strain at break values (392%—1150%), manifesting the typical features of thermoplastics.…”

Section: Resultsmentioning

confidence: 99%

Enhancing Suppression of Chain Transfer via Catalyst Structural Evolution in Ethylene (Co)Polymerization

et al. 2023

Self Cite

View full text Add to dashboard Cite

Comprehensive SummaryUsually, the aniline‐based late‐transition‐metal catalysts often require bulky steric substituents on both sides of the ortho‐aryl position to achieve efficient suppression of chain transfer in ethylene polymerization. In this contribution, we demonstrated that α‐diimine catalysts based on naphthylamine with only one bulky ortho‐aryl substituent also demonstrated excellent capabilities to suppress the chain transfer. Firstly, a class of α‐diimine nickel and palladium complexes with only one o‐aryl‐dibenzhydryl or o‐aryl‐dibenzosuberyl substituent were synthesized and characterized. Secondly, the as‐prepared naphthylamine‐based nickel catalysts demonstrated outstanding activities (up to 13.02 × 106 g·mol–1·h–1) and yielded lightly branched (16—40/1000C) polyethylenes with very high molecular weights (445.8—854.3 kg/mol) in ethylene polymerization. In comparison, the corresponding palladium catalysts showed moderate activities (level of 104—105 g·mol–1·h–1), generating moderately branched (47—78/1000C) polyethylenes with moderate molecular weights (21.6—82.0 kg/mol). Moreover, the palladium catalysts could also copolymerize ethylene and methyl acrylate (MA), albeit in low activities (level of 103 g·mol–1·h–1), providing E‐MA copolymers with low to moderate molecular weights (1.4—16.3 kg/mol) and a moderate level of incorporation ratio (2.4—7.4 mol%) and branching density (53—84/1000C). As compared with aniline‐based nickel and palladium catalysts, the naphthylamine‐based catalysts displayed a superior ability to suppress the chain transfer reactions and could give access to (co)polymers with orders of magnitude higher molecular weight in ethylene (co)polymerization.

show abstract

Section: Resultsmentioning

confidence: 99%

Enhancing Suppression of Chain Transfer via Catalyst Structural Evolution in Ethylene (Co)Polymerization

et al. 2023

Self Cite

View full text Add to dashboard Cite

show abstract

“…The molecular weight of the polar polyethylene produced is reduced by an order of magnitude compared with that of the polyethylene obtained in the homopolymerizations (Table ). It should be emphasized that the MA incorporation ratios in our current study are high (8.5–21.4 mol %), substantially exceeding those of the α-diimine palladium system under similar conditions. − A higher concentration of methyl acrylate (MA) is beneficial for obtaining higher insertion ratios (Table ). The Pd catalyst in this system demonstrates an exceptional ability to insert MA, resulting in an increased density of polar functional groups in the resultant polyethylene.…”

Section: Resultsmentioning

confidence: 67%

Palladium-Catalyzed Synthesis of Hyperbranched Polar Functionalized Polyethylene with High Density Hydrophilic Groups

Ding,

Dai

2023

ACS Appl. Polym. Mater.

Self Cite

View full text Add to dashboard Cite

The chain-walking polymerization (CWP) strategy is a promising concept for the convenient synthesis of hyperbranched polar functionalized polyethylene with unique properties. In this study, we synthesized and described a series of o-aryl monosubstituted dibenzosuberyl iminopyridine ligands containing benzocycloalkyl or naphthyl moieties as well as the corresponding Pd(II) complexes, in a highly efficient manner. The Pd(II) complexes catalyzed efficient ethylene chain walking polymerization to produce hyperbranched polyethylenes (HBPEs) with high molecular weights (M n values up to 71.4 kg/mol). Notably, copolymerization of ethylene and methyl acrylate, catalyzed by iminopyridine Pd(II) complexes, resulted in successful polar functionalized HBPEs with high density hydrophilic groups (21.4 mol %) at the end of branching. The polar functionalized HBPEs resulting from the process are saponified or reduced to yield more hydrophilic polymers that can solubilize water-insoluble drug molecules.

show abstract

“…[25][26][27] Chen, Dai and their co-workers observed that the bulky ortho N-aryl substituents on α-diimine ligands enable the Pd(II) catalysts to yield PE with apparently higher molecular weight (level of 1000 kg/mol) and significantly lower branching density (6-26/1000 C). [28][29][30][31][32][33][34] The significantly lower branching density and higher molecular weight resulting in the semi-crystalline structure dramatically improves the mechanical properties of polymer materials. The Harth group introduced the m-xylyl substituents to the α-diimine Pd(II) complexes, in which the catalyzed living ethylene polymerization was observed.…”

Section: Introductionmentioning

confidence: 99%

“… 24 In order to generate the various branched PEs with the α‐diimine catalytic system, the ligands were always introduced with different hindrance 25–27 . Chen, Dai and their co‐workers observed that the bulky ortho N‐aryl substituents on α ‐diimine ligands enable the Pd(II) catalysts to yield PE with apparently higher molecular weight (level of 1000 kg/mol) and significantly lower branching density (6–26/1000 C) 28–34 . The significantly lower branching density and higher molecular weight resulting in the semi‐crystalline structure dramatically improves the mechanical properties of polymer materials.…”

Section: Introductionmentioning

confidence: 99%

Functionalized semi‐crystalline polyethylene with polar groups at branch end enabled by bulky cationic palladium catalysts

Wu,

Zou,

Dai

2023

Journal of Polymer Science

Self Cite

View full text Add to dashboard Cite

Transition metal‐catalyzed copolymerization of ethylene with polar monomers is the most direct and efficient way to prepare polar functionalized polyethylene. Generally, the classical Brookhart type α‐diimine Pd(II) catalysts produced hyperbranched functionalized polyethylene with polar groups at the branch ends, which turns out to be amorphous polymer materials. In this contribution, we described the synthesis and characterization of three bulky diarylmethyl α‐diimine ligands and the corresponding Pd(II) complexes. Lightly branched (21–27/1000C) polyethylenes with high molecular weights (317.8–640.0 kg/mol) and high melting points (94–101°C) were prepared using these Pd(II) complexes at high activities (well above 105 g/mol.h). The resulting polyethylene materials exhibited high stress (23.8‐34.3 MPa) and high strain (559–839%) at break values with typical properties of thermoplastics. Polar functionalized semi‐crystalline polyethylenes with moderate incorporation ratios (0.35–2.99 mol%) and high melting points (84–109°C) were prepared using complexes Pd1‐3 in the copolymerization of ethylene with several polar comonomers (methyl acrylate and 10‐undecenoic acid and 10‐methyl undecanoate). The 1H and 13C NMR spectral analysis revealed that these polar functionalized polyethylenes have a low branching density (19–34/1000C) and are predominantly methyl‐branched, with polar groups located at the end of the branches. In addition, the 4‐methoxy group on the ligands in this work would facilitate the insertion of polar monomers in the copolymerization of ethylene with various polar monomers.

show abstract

A rigid–flexible double-layer steric strategy promoting ethylene polymerization and copolymerization in alkane solvents

Abstract: In this study, a series of double-layer steric α-diimine nickel and palladium complexes containing bulky diarylmethyl moieties with remote 4-cycloalkyl and -phenyl substituents were designed and synthesized. The as-synthesized nickel...

Cited by 20 publications

References 47 publications

Enhancing Suppression of Chain Transfer via Catalyst Structural Evolution in Ethylene (Co)Polymerization

Enhancing Suppression of Chain Transfer via Catalyst Structural Evolution in Ethylene (Co)Polymerization

Palladium-Catalyzed Synthesis of Hyperbranched Polar Functionalized Polyethylene with High Density Hydrophilic Groups

Functionalized semi‐crystalline polyethylene with polar groups at branch end enabled by bulky cationic palladium catalysts

Contact Info

Product

Resources

About