Post-metallocene catalysts for the synthesis of ultrahigh molecular weight polyethylene: Recent advances

Novel titanium(IV) diolate complexes with additional O‐donor as precatalyst for the synthesis of ultrahigh molecular weight polyethylene with reduced entanglement density: Influence of polymerization conditions and its implications on mechanical properties

“…In the overwhelming majority of cases, disentangled UHMWPE suitable for solid‐phase processing is synthesized on phenoxy‐imine Group 4 metal complexes (FI catalysts [ 9 ] ), activated with alkylaluminoxanes. [ 10–14 ] However, these activators have significant drawbacks that lie in the high Al/M ratios needed to achieve optimal catalytic performance and in its still ill‐defined structures (mixture of oligomers (AlO(Alk)) n evolving with time). In addition, these activators increase considerably the catalyst costs.…”

Synthesis of Ethylene/1-Octene Copolymers with Ultrahigh Molecular Weights by Zr and Hf Complexes Bearing Bidentate NN Ligands with the Camphyl Linker

“…Copolymerization of ethylene and 1-octene with these metal complexes have been investigated, and the preliminary results show that Zr complexes have moderate activity (up to 388 kg(PE)•mol −1 (M)•h −1 ), poor copolymerization ability (less than 1 mol%), but unprecedented molecular weight capability (> 600 × 10 4 g•mol −1 ) toward ethylene/1-octene copolymerization, while Hf complexes show negligible activity under otherwise identical conditions. Note that Ultrahigh molecular weight polyethylenes (UHMWPE) have a unique set of properties such as high chemical resistance, outstanding mechanical property, good corrosion stability, excellent abrasive wear resistance, and thus are extensively used as a class of high-performance engineering plastics [50,51].…”

Preparation of High-Purity Ammonium Tetrakis(pentafluorophenyl)borate for the Activation of Olefin Polymerization Catalysts

“…A set of signals assigned to ortho-, para-, and meta-fluorine in the [B(C 6 F 5 ) 4 ] − ion was clearly observed at −132.22, −161.72, and −165.95 ppm, respectively, in the 19 F NMR spectrum. No Cl − anions were detected in the product; treatment of [(CH 3 CN) 4 Ag] + [B(C 6 F 5 ) 4 ] − with a diethyl ether solution containing the product did not generate any AgCl precipitates, which indicated that LiCl was thoroughly removed by washing with water (Supplementary Materials Figure S1b). The byproduct LiCl can also be removed by filtration [38].…”

“…In the 1 H NMR spectrum, the NCH 2 signals were fairly sharp, showing a splitting pattern, but the N-H signal was absent, possibly due to broadening (Figure 1b). Treatment of [(CH 3 CN) 4 Ag] + [B(C 6 F 5 ) 4 ] − with a solution containing the product changed the clear solution turbid due to the formation of AgCl particles (Supplementary Materials Figure S1c), which indicated that the product was contaminated with Cl − ions.…”

“…The initial metallocene complexes (i.e., L -MCl 2 -type complexes, where L and M are cyclopentadienyl-type ligands and group-four metals, respectively) have been followed by the development of half-metallocene complexes, in which one of the two cyclopentadienyl-type ligands in metallocenes is replaced with an amido or aryloxo ligand, and further by post-metallocene complexes that do not contain any cyclopentadienyl-type ligands [ 2 , 3 ]. The central group-four transition metals have also been expanded to Ni, Pd, Fe, Co, Cr, and V, especially in post-metallocene complexes [ 4 , 5 , 6 , 7 ]. Metallocene, half-metallocene, and post-metallocene complexes are not active, and must be activated with a co-catalyst.…”