Group 3 metal catalysts for ethylene and α-olefin polymerization

Gromada, Jérôme; Carpentier, Jean‐François; Mortreux, André

doi:10.1016/j.ccr.2004.02.002

Cited by 288 publications

(142 citation statements)

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“…They have successfully been utilized as hydrometalation catalysts as well as single component, single-site olefin polymerization catalysts without the necessity of cocatalysts. [21] A similar isoelectronic relationship exists with the 14-electron cationic half-sandwich complex of the type [Ln(h 5 -C 5 R 5 )(L) 3 …”

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confidence: 84%

Cationic Alkyl Complexes of the Rare‐Earth Metals: Synthesis, Structure, and Reactivity

2005

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This contribution is dedicated to Dick Schrock on the occasion of his 60th birthday.Abstract: Cationic alkyl complexes of the rare-earth metals [LnR m ; L ¼ Lewis base) were virtually unknown species until recently. Because of their increased Lewis acidity/electrophilicity they should have considerable potential as homogeneous catalysts in olefin polymerization and in organic transformations. They can be generated by treating the neutral rare-earth metal precursors containing at least two alkyl groups R with suitable Lewis or Brønsted acids in the presence of weakly coordinating anions. Not only monocationic but also dicationic alkyl derivatives have been shown to be accessible. In the context of modeling homogeneous ethylene polymerization using a mixture consisting of LnR 3 /AlR 3 /[NMe 2 HPh][B(C 6 F 5 ) 4 ], such dications were discovered. Some thermally robust examples of mono-and dicationic alkyl complexes have been structurally characterized as solvent-separated ion pairs. Neutral and monoanionic macrocycles such as crown ethers or aza-crown ethers as well as amidinato, b-diketiminato, and substituted cyclopentadienyl ligands are suitable ancillary ligands to stabilize the cationic alkyl fragments.

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confidence: 84%

Cationic Alkyl Complexes of the Rare‐Earth Metals: Synthesis, Structure, and Reactivity

2005

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“…Due to the absence of polar groups, semi-crystalline morphology, resistance to polar or ionic chemicals and limited chemical substitution, oxidation and free radical reactions, these modifications are quite challenging and usually are difficult to maintain [5]. There are two main modification methods in the literature: (i) direct copolymerization of either α-olefin [6,7] or polar monomers [8,9] and (ii) chemical modification of preformed polymers [10,11]. For example, antibacterial [12], antifouling [13] and hydrogen storage [14] properties of polypropylene were enhanced via surface-initiated atom transfer radical polymerization [15].…”

Section: Introductionmentioning

confidence: 99%

Polypropylene-based graft copolymers via CuAAC click chemistry

Açık¹,

Sey²,

Taşdelen³

2018

Express Polym. Lett.

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Abstract. Graft copolymers from commercial chlorinated polypropylene (PP-Cl) possessing either poly(ethylene glycol) (PEG) or poly(ɛ-caprolactone) (PCL) grafts are synthesized by copper (I)-catalyzed azide-alkyne cycloaddition 'click' reaction (CuAAC). For this purpose, azido-functional polypropylene is prepared by nucleophilic substitution of chlorine groups of PP-Cl with azidotrimethylsilane-tetrabutylammonium fluoride. Whereas, the clickable alkyne end-functional PEG and PCL are independently synthesized by esterification reaction of poly(ethylene glycol) methyl ether with 4-pentyonic acid at room temperature and ring-opening polymerization of ε-caprolactone using stannous octoate as catalyst and propargyl alcohol as initiator. Finally, the corresponding graft copolymers, PP-g-PEG and PP-g-PCL, with different surface properties were successfully synthesized by CuAAC 'click' reaction under mild condition. Spectral, chromatographic and thermal analyses at various stages prove the formation of desired polypropylene-based graft copolymers with well-defined properties. Furthermore, the water contact angle values of PP-Cl, PP-g-PEG and PP-g-PCL are found as 90±1°, 78±1.8° and 83±2.1°, respectively.

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“…2,3 Among these complexes, hydrides and alkyls were the most preferred. However, if the lanthanide hydrides have been proved to be powerful catalysts towards a lot of interesting chemical transformations, their access remains a challenging problem, since they are exceedingly reactive.…”

Section: Introductionmentioning

confidence: 99%