Formation of branched polyethylenes by ethylene homopolymerization using LNiBr₂ homo‐ and heterogeneous precatalysts: Interpretation of the polymer structures in comparison with commercial LLDPE

Abstract

Comparative data on the micro‐structures and properties of branched polyethylenes (BPE) produced via ethylene homopolymerization over homogeneous N,N‐α‐diimine LNiBr2 complexes with different ligand composition (AlEt2Cl as a cocatalyst) and corresponding supported catalysts LNiBr2/SiO2(Al) (Al[iso‐Bu]3 as a cocatalyst) are presented. Noticeable differences were observed between micro‐structures of BPEs obtained using homo‐ and heterogeneous LNiBr2 complexes as catalysts. Supported catalysts produce BPEs with the majority of methyl branches (17–18 CH3(1000 C)−1 characterized by different molecular masses (1800–210 kg mol−1) and molecular weight distributions (Mw[Mn]−1 = 5.9 and 2.6). Thermal and mechanical properties of these BPE samples obtained over supported Ni catalysts are similar to those of commercial LLDPE samples prepared with metallocene and Ziegler‐Natta catalysts.

Syntheses of Silylene-Bridged Thiophene-Fused Cyclopentadienyl ansa-Metallocene Complexes for Preparing High-Performance Supported Catalyst

“…When a homogeneous catalyst is injected, as dissolved, into a slurry-or gas-phase reactor, the shape and size of the generated polymer particles are irregularly uncontrolled, making stable operation impossible (termed 'fouling') as well as causing low productivity due to low bulk density. Because a large portion of PE and PP is produced by the slurry and gas-phase processes, high-performance supported catalysts are essential in the industrial sector [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26].…”

Synthesis and Properties of Ethylene/propylene and Ethylene/propylene/5-ethylidene-2-norbornene Copolymers Obtained on Rac-Et(2-MeInd)2ZrMe2/Isobutylaluminium Aryloxide Catalytic Systems

“…Stepwise isothermal crystallization from polymer melt is a useful technique for the evaluation of the chain heterogeneity in such copolymers [ 35 , 36 , 37 , 38 ]. The DSC curves of thermally fractionated copolymers are presented in Figure 3 b,c.…”

From tetramerization to oligomerization/polymerization of ethylene by dinuclear pyridyl‐imine Co‐ and Ni‐based catalysts

“…[4][5][6] On the other way, there are many reports on late transition metal (LTM) complexes as an interesting class of catalysts due to feasibly preparation and modification, capability of production of a wide range of polyethylene/oligoethylene, intriguing and unusual behavior (e.g., chain-walking olefin polymerization). 1,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Multinuclear LTM catalysts along with their mononuclear analogs are widely used for preparation of ethylene homopolymers/copolymers and oligomers. [22][23][24] In the most cases, not only higher catalytic activity has been observed but also metal-metal cooperative effect in terms of greater selectivity in products has been reported.…”

“…These structures are massively various and belonged to different generation of catalyst systems 4–6 . On the other way, there are many reports on late transition metal (LTM) complexes as an interesting class of catalysts due to feasibly preparation and modification, capability of production of a wide range of polyethylene/oligoethylene, intriguing and unusual behavior (e.g., chain‐walking olefin polymerization) 1,7–21 …”