Carbon Nanotubes as a Ligand in Cp₂ZrCl₂‐Based Ethylene Polymerization

Abstract

Summary: We report a simple method for tuning catalytic property of a metallocene‐based catalyst, Cp2ZrCl2, for ethylene polymerization by the direct adsorption of Cp2ZrCl2 onto multi‐walled carbon nanotubes (MWCNTs). The direct interactions between MWCNTs and the Cp rings of Cp2ZrCl2 controlled the polymerization behaviors, and we could generate polyethylene with an extremely high molecular weight ($\overline M _{\rm w}$ = 1 000 000) at 30 °C and under 1 atm of ethylene gas.Preparation of Cp2ZrCl2‐MWCNT.magnified imagePreparation of Cp2ZrCl2‐MWCNT.

Synthesis, characterization and crystallization kinetics of nanocomposites prepared by in situ polymerization of ethylene and graphene

“…Park et al used MWCNTs adsorbed with zirconocene to synthesize PE with high M w and MWD. The increase in M w was attributed to electronic and steric effect of MWCNTs [18]. Similarly, Stürzel et al [19] prepared UHMWPE by using functionalized graphene as a support for the single-site chromium catalyst.…”

“…The highest M w is obtained with 10 mg of filler. The increase in the M w can be due to the steric and electronic effect of graphene [18,28]. It has been found that the M w of metallocene-polymerized polymers increases with electron donating effect [29].…”

“…For instance, the steric effect of graphene and CNTs can be utilized to tune the molecular weight, molecular weight distribution (MWD) and catalytic activity of singlesite catalyst. Park et al [18] used multi-walled carbon nanotubes (MWCNTs) adsorbed with zirconocene to synthesize high M w PE with high MWD. Stürzel et al [19] prepared ultra-high molecular weight polyethylene (UHMWPE) by using functionalized graphene as a support for the single-site chromium catalyst.…”

Production of Ultrahigh‐Molecular‐Weight Polyethylene/Pristine MWCNT Composites by Half‐Titanocene Catalysts

“…[24] The molecular weight of the PE was found to be increased by this method. Based on these results, we reasoned that our method, using CNT-supported catalysts, should lead to the production of pristine CNT/ UHMWPE composites with a uniform dispersion of CNTs in a UHMWPE matrix, if the catalyst was properly chosen.…”

“…CNT/polyethylene (PE) composites have been formed by ultrasonication, mechanical mixing of CNTs and melted polymers, [19][20][21] in situ polymerization with CNTs, [4] the use of functionalized CNTs to enhance the affinity of CNTs toward the polymer matrices, [22] and the use of catalysts or initiators immobilized onto CNTs. [23][24][25] However, as far as we know, the production of pristine CNT/UHMWPE composites has been unsuccessful up to now, because of the insolubility of UHMWPE, and its high viscosity in the melted form.…”