Homo- and Copolymerization of 4-Methyl-1-pentene and Ethylene with Group 4 ansa-Cyclopentadienylamido Complexes

Abstract

A new monocyclopentadienylamido complex, [η5:η-(2,3-Me2Benz[e]Ind)SiMe2N t Bu]TiCl2 (I), was synthesized as catalyst precursor. The studies on the homopolymerization and copolymerization of 4-methyl-1-pentene (P) and ethylene (E) were presented, by comparing complex I with other CpA complexes and Cp2M zirconocenes. The complex I, activated with methylaluminoxane, provided an enhanced copolymerization activity, an excellent incorporation of 4-methyl-1-pentene into the polyethylene chain, and an increased copolymer molecular weight. Analysis of 13C NMR spectra of polymers, combined with the monomer reactivity ratios and the polymerization results, demonstrated that the regioselectivity of monomer insertion, tacticity, productivity, molecular weights, and polymer microstructure are significantly dependent on the ligand substitution pattern and the metal atom in CpA complexes. The CpA I-derived poly(4-methyl-1-pentene-co-ethylene)s contained a significant amount of regioirregular arrangement of 4-methyl-1-pentene unit, but with no virtually consecutive 4-methyl-1-pentene sequence. In contrast, the [η5:η1-(Me4C5)SiMe2N t Bu]TiCl2 (IV)-derived copolymers revealed the small clustered sequence (e.g., EPPE) but without any regioirregular arrangement of 4-methyl-1-pentene units. The copolymers prepared with [η5:η1-(Flu)SiMe2N t Bu]TiCl2 (VI) not only showed quite different microstructure from that based on catalysts I and IV but also manifested the more pronounced tendency to form an alternating distribution of monomers in the polymer chains. Furthermore, the VI-derived copolymer contained neither a regioregular insertion of comonomer nor the consecutive 4-methyl-1-pentene sequences.

Ethylene/4‐Methyl‐1‐pentene Copolymers by a “Constrained Geometry Catalyst”: Advances in 13C NMR Assignment

“…[5,6] Their open structure permits an even easier incorporation of bulky a-olefins in addition to that of ethylene macromonomers. [6][7][8][9][10] Ethylene-based copolymers with high levels of 4M1P comonomer incorporation have been prepared with various structured CGCs. [9] A further advantage offered by alkyl and dialkyl CGCs is the higher thermal stability when compared to related metallocenes, [11,12] which allows for higher polymerization temperatures.…”

“…[6][7][8][9][10] Ethylene-based copolymers with high levels of 4M1P comonomer incorporation have been prepared with various structured CGCs. [9] A further advantage offered by alkyl and dialkyl CGCs is the higher thermal stability when compared to related metallocenes, [11,12] which allows for higher polymerization temperatures. The chemistry of these catalysts has experienced a rapid advancement, particularly because catalytic systems based on such compounds have given access to a wide array of polymers with unique properties and considerable commercial value.…”

(nBuCp)2ZrCl2‐catalyzed ethylene‐4M1P copolymerization: Copolymer backbone structure, melt behavior, and crystallization

“…Several groups worked on E-4M1P solution copolymerization to investigate catalyst structure-activity relationship, influence of polymerization conditions, comonomer effect, and copolymer microstructure (as appropriate). 18,[20][21][22][23][24][25] Conversely, Awudza and Tait 26 show to be the only group that studied E-4M1P slurry copolymerization, using supported silica/MAO/Cp 2 ZrCl 2 catalyst, where Cp 2 ZrCl 2 stands for bis(-cyclopentadienyl) zirconium dichloride. They primarily investigated comonomer effect.…”

Complex Branched Polyolefin Generated from Quasi-living Polymerization of 4-Methyl-1-pentene Catalyzed by α-Diimine Palladium Catalyst

“…The obtained products are viscous oil at a low 4MP concentration ([4MP] < 0.8 M), while the obtained polymers are wax when monomer concentration is 3.2 M. The determinations of GPC show that the obtained poly(4MP)s have high molecular weights (M n > 24 000), indicating that the obtained polymers have unique branches and complex structure, which is obviously different from the isotactic poly(4MP) produced by early transition metal center catalyst. [12,13] 1 H NMR was carried out to study the microstructure of the poly(4MP), and a typical spectrum was shown in Figure 1. Methyl signals are observed in the broad region form 0.75 to 0.90 ppm.…”