Homo-and copolymerization of propylene and ethylene in the presence of titanium dichloride complexes with dioxolane dicarboxylate and bis(difurylmethanephenoxyimine) ligands

The polymerization of propylene and ethylene and the copolymerization of these olefins with postmetallocene catalysts (4R,5R)-2,2-dimethyl-α,α,α′,α′-tetra(perfluorophenyl)-1,3-dioxolane-4,5-dimethanol] titanium(IV) dichloride and bis{N-(3,5-ditert-butylsalicylidene)-4-bis(5-methyl-2-furyl)methyl]aniline}titanium( IV) dichloride have been studied. The polymerization of propylene and its copolymerization with ethylene have been carried out in a liquid monomer, while the polymerization of ethylene has been performed in toluene at the constant concentration of the monomer. Polymethylaluminoxane has been used as a cocatalyst. The activity of the catalysts in the polymerization of propylene and ethylene at 50°C is ～ 10 and ～45 kg PP/mol Ti h mol C₃H₆/l and 178.5 and 2700 kg PE/mol Ti h mol C₂H₄/l, respectively. It has been established that, in the copolymerization of propylene with ethylene, the active sites of both catalysts selectively polymerize ethylene. The resulting copolymers have a block structure (r ₁ r ₂= 4.6); as a result, the crystalline phase of polyethylene is formed in them. Polypropylene and propylene-ethylene copolymers are elastomeric materials. Polypropylene samples synthesized with (4R,5R)-2,2-dimethyl-α,α,α′,α′-tetra(perfluorophenyl)-1,3-dioxolane-4,5-dimethanol]titanium(IV) dichloride demonstrate a high melting point (150–157°C) in combination with good elastic properties. Polyethylene is a linear polymer with the degree of crystallinity varying from 37 to 45% and a melting point of 133–134°C. The mechanical properties of the polymers and copolymers have been investigated.