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

Autor: Daniele Saracheno, Alexander Sizov, Olga Smirnova, Boris M. Bulychev, Vladislav A. Tuskaev, A. G. Buyanovskaya, Svetlana Ch. Gagieva, T. M. Zvukova
Rok vydání: 2020
Předmět:
Zdroj: Polymer Bulletin. 78:1967-1979
ISSN: 1436-2449
0170-0839
Popis: The synthesis and olefin polymerization behavior of a new TADDOL-based Ti(IV) complex, (4R,5R)-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 [C2H4]−1 h−1 atm−1 and molecular weights up to 3.25 × 106. 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 13C 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 [C2H4]−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 (Mw = 1.4 × 106—ethylene/1-hexene and 1.86 × 106—ethylene/1-octene) with broad MWD (Mw/Mn = 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.
Databáze: OpenAIRE
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