Synthesis of LDPE Using Pyridineimine‐Based Nickel (II) Bromide Complexes: Effect of Catalyst Bulkiness on Thermal, Structural, and Morphological Properties

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/mren.201800006. Pyridine-Imine CatalystA series of pyridine-imine [N-N] ligands are efficiently prepared through the condensation reaction of ketone/aldehyde precursor and synthesized aniline. The ligands (L n , n = 1-4) and corresponding nickel complexes (C n , n = 1-4) are characterized and used for polymerization of ethylene in the presence of modified methylaluminoxane as cocatalyst. The produced low density polyethylenes show at least 21 branches per 1000 carbon atoms with M v values up to 80.0 × 10 4 . Aldimino-based catalyst is more active than the analogue catalyst, although, ketimines result in polyethylene with higher M v . Nevertheless, the product of aldimino-based catalyst indicates the highest melting point of 132.3 °C but ketimine exhibits the highest crystallinity of 32.98% at the same polymerization conditions. Specific morphologies including smooth spherical and irregular porous particles are observed for some polymer samples. However, at high polymerization temperatures and different monomer pressures, different morphologies as well as two melting point peaks are observed in scanning electron microscopy (SEM) images and differential scanning calori meter thermograms, respectively.

Structural evolution of iminopyridine support for nickel/palladium catalysts in ethylene (oligo)polymerization

“…However, these catalysts were noteworthy for their high stability for a long time reaction, and therefore are potential candidates for industrial application in the synthesis of low molecular weight PE. 29 Recently, Wang et al examined a similar class of nickel and palladium catalysts ( 22 and 23 and Pd1 and Pd2 , Fig. 6), respectively.…”

Unraveling Organoboron/Nickel Ion-Pair Interactions via Benchtop-Stable Carbyl Iminopyridyl NiII Complexes for Olefin Polymerization

“…1). 23,[30][31][32][33] The more rigid and bulkier L6L8 were designed to further investigate the rotational barrier with sterically bulkier orthosubstituents on the Naryl moiety. The complexations were achieved either by ligand exchange using (PPh 3 ) 2 Ni(oTol)Cl or by oxidative addition with Ni(COD) 2 and 2chlorotoluene (Fig.…”

Ethylene/α-olefin homo- and copolymerization using a dinuclear catalyst of nickel

“…One of the research studies with a long and prominent history is the conversion of cheap ole nic monomers (such as ethylene and propylene) into widely used polyole nic materials though transitionmetal complexes [1][2][3]. In this regard, late transition metal (LTM) catalysts have been so far incorporated into a great deal of investigations, thanks to their diversity and interesting behaviors in the structure of chelating ligands and metal centers [4,5].…”