Novel titanium (IV) diolate complexes with thiophene-containing OSO-type ligand as pre-catalyst for ethylene polymerization and ethylene - propylene copolymerization

New Titanium(IV)-Alkoxide Complexes Bearing Bidentate OO Ligand with the Camphyl Linker as Catalysts for High-Temperature Ethylene Polymerization and Ethylene/1-Octene Copolymerization

“…The nature of the organoaluminum compound (OAC) included in the Al/Mg activator did not significantly affect these parameters. The results obtained slightly exceeded those previously published for titanium complexes with diol ligands [ 17 , 18 , 21 , 25 , 26 , 27 ]; however, the reason may be not only the structure of the precatalysts, but also the polymerization temperature (in the cited works, polymerization was carried out at 30 °C). For comparison, the modulus value for commercially available gel-spun UHMWPE fiber, produced by the gel-spinning process, is 113 GPa [ 38 ].…”

“…Previously, we reported on the ability of various titanium(IV)–diolate complexes VII-X [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], including those with additional heteroatoms [ 23 , 24 , 25 , 26 , 27 ] ( Chart 1 ), to catalyze the (co)polymerization of ethylene in the presence of such Al/Mg activators. This group of postmetallocene precatalysts is poorly studied, which is most likely due to the specifics of their activation: in the presence of trialkylaluminum derivatives, alkylaluminum chlorides, or alkylalumoxanes (traditional activators in Ziegler–Natta catalysis), and the activity of these systems is low or does not manifest itself at all.…”

“…An essential point limiting the possibility of the industrial implementation of this group of catalysts is their low thermal stability. As a rule, the maximum productivity of such systems is achieved at a temperature of 30 °C [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]; an increase in the polymerization temperature to 50–80 °C is accompanied by deactivation and a significant reduction in the polymer’s molecular weight. The aim of this work is the structural modification of the ligand environment of the metal, aimed at increasing the thermal stability of the considered precatalysts.…”

Trends in Structure and Ethylene Polymerization Reactivity of Transition-Metal Permethylindenyl-phenoxy (PHENI*) Complexes

“…77 Alkylated permethylindenyl metallocenes, supported on sMAO, have been shown previously to have higher ethylene polymerization activities than the parent halide complexes. 24 However, in the current work, the methyl (10) and neosilyl (11) complexes demonstrated activities comparable to iodide (9) and less than both bromide (8) and chloride (2), with benzyl (12) having still lower activities. These results suggest that precatalyst activation is comparatively facile, with steric, electronic, conformational, and secondary coordination effects dominating the propagation kinetics.…”

“…This leads to increased activities, generally higher molecular weight polymers, and also the ability to incorporate comonomers with high efficiency . The development of new generations of CGCs and related postmetallocene catalystsmany of which incorporate phenoxide ligandsis an area of ongoing intensive research. − …”