Ethylene homopolymerization and copolymerization with 1-hexene and 1-octene catalyzed by titanium(IV) dichloride TADDOLate complex activated with MAO

• Published in: Polymer bulletin (Berlin, Germany) Germany), 2021-04, Vol.78 (4), p.1967-1979
• Main Authors: Gagieva, Svetlana Ch, Tuskaev, Vladislav A., Saracheno, Daniele, Buyanovskaya, Anastasiia G., Smirnova, Olga V., Zvukova, Tamara M., Sizov, Alexander I., Bulychev, Boris M.
• Format: Article
• Language: English
• Subjects: Block copolymers; Characterization and Evaluation of Materials; Chemical synthesis; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Copolymerization; Dichlorides; Ethanol; Ligands; Molecular weight; NMR; Nuclear magnetic resonance; Octenes; Organic Chemistry; Original Paper; Physical Chemistry; Polymer Sciences; Polymerization; Polymers; Pressure vessels; Soft and Granular Matter; Solvents; Stainless steel; Temperature; Titanium; Ultra high molecular weight polyethylene
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-020-03195-3

The synthesis and olefin polymerization behavior of a new TADDOL-based Ti(IV) complex, (4 R ,5 R )-2,2-dimethyl-α,α,α′,α′-tetrakis[bis-(3,5-trifluoromethyl)phenyl]-1,3-dioxolane-4,5-dimethanolato-titanium(IV) dichloride, are described. Upon activation with MAO, this complex polymerized ethylene, producing ultra-high molecular weight linear polyethylene (UHMWPE) with activities up to 4500 kg mol (Ti) −1  [C 2 H 4 ] −1  h −1  atm −1 and molecular weights up to 3.25 × 10 6 . The optimal temperature for UHMWPE synthesis was 50 °C. This complex is also capable of copolymerizing ethylene with 1-hexene and 1-octene, giving high molecular weight copolymers with α-olefin incorporation up to 7.8%. The copolymers, obtained with a different ratio of comonomers, are statistical, according to the analysis of the 13 C NMR spectra. The reaction parameters that influenced the copolymerization behavior, such as comonomer concentration, reaction temperature and [Al]/[Ti] molar ratio, are examined in detail. Furthermore, high catalytic activities up to 12,531 kg mol(Ti) −1  [C 2 H 4 ] −1  h −1  atm −1 were observed in copolymerization of ethylene and 1-hexene or 1-octene with the 2 /MAO catalytic system. The obtained copolymers possess high molecular weights ( M w  = 1.4 × 10 6 —ethylene/1-hexene and 1.86 × 10 6 —ethylene/1-octene) with broad MWD ( M w / M n  = 3.04–8.23) and high comonomer incorporation degrees (up to 6.2 mol% of 1-hexene and 7.8 mol% of 1-octene). Depending on the synthesis conditions, it is possible to form both a statistical copolymer and a block copolymer.