Design of Efficient Molecular Catalysts for Synthesis of Cyclic Olefin Copolymers (COC) by Copolymerization of Ethylene and α-Olefins with Norbornene or Tetracyclododecene

Abstract

Abstract:Selected results for the synthesis of cyclic olefin copolymers (COCs)-especially copolymerizations of norbornene (NBE) or tetracyclododecene (TCD) with ethylene and α-olefins (1-hexene, 1-octene, 1-dodecene)-using group 4 transition metal (titanium and zirconium) complex catalysts have been reviewed. Half-titanocenes containing an anionic ancillary donor ligand, Cp'TiX 2 (Y) (Cp' = cyclopentadienyl; X = halogen, alkyl; Y = anionic donor ligand such as aryloxo, ketimide, imidazolin-2-iminato, etc.), are effective catalysts for efficient synthesis of new COCs; ligand modifications play an important role for the desired copolymerization. These new COCs possess promising properties (high transparency, thermal resistance (high glass transition temperature), low water absorption, etc.), thus it is demonstrated that the design of an efficient catalyst plays an essential role for the synthesis of new fine polyolefins with specified properties.

Titanium and Vanadium Catalysts with 2-Hydroxyphenyloxazoline and Oxazine Ligands for Ethylene-Norbornene (co)Polymerization

“…Typically, the molecular weight (M w ) of the obtained copolymers is considerably lower than that for polyethylene and decreases with increase of the initial norbornene concentration [12,24,40]. The studied catalysts produce the copolymer with M w in the range of (2.6-0.9 × 10 5 g/mol) and its decrease is observed especially for the catalyst with the ligand L2.…”

“…The obtained values of T g (4-62 • C) strictly depend on the amount of NB comonomer. Such a linear dependence indicates that the copolymer has homogeneous composition [12,24]. The relatively low T g values can be explained a relatively low NB incorporation [41].…”

“…One of the methods to do this is to use a designed catalyst that has a direct impact on the molecular structure of copolymer, which in turn affects its properties [1,6,7,[10][11][12][13][14][15][16]. The key factor determining tacticity and distribution of mers in the polymer chain is catalyst symmetry, which depends on the presence of various ligands in the coordination sphere of transition metal [1,[6][7][8][9][10][11][12][13][14][15][16][17][18]. Similar to the synthesis of polyethylene and ethylene copolymers with 1-olefins, in particular E-NB copolymers, the catalysts with zirconium [1,6,12,19] and titanium [8,12,20] atoms in the active center are the most often studied.…”

“…The key factor determining tacticity and distribution of mers in the polymer chain is catalyst symmetry, which depends on the presence of various ligands in the coordination sphere of transition metal [1,[6][7][8][9][10][11][12][13][14][15][16][17][18]. Similar to the synthesis of polyethylene and ethylene copolymers with 1-olefins, in particular E-NB copolymers, the catalysts with zirconium [1,6,12,19] and titanium [8,12,20] atoms in the active center are the most often studied. The vanadium catalysts [21,22] are less studied, but they receive interest because it is possible to obtain the E-NB copolymers with high molecular weight, narrow molecular weight distribution, and high norbornene incorporation [13,[15][16][17][18][23][24][25][26].…”

“…The vanadium catalysts [21,22] are less studied, but they receive interest because it is possible to obtain the E-NB copolymers with high molecular weight, narrow molecular weight distribution, and high norbornene incorporation [13,[15][16][17][18][23][24][25][26]. In contrast to the zirconium and titanium catalysts, which work best after methylaluminoxane (MAO) activation [1,[6][7][8]12,19,20], the vanadium catalysts reveal the best performance when activated by AlEt 2 Cl in the presence of reactivator, ethyl trichloroacetate (ETA), which prevents reduction of the vanadium atom to lower oxidation states and influences positively termination and re-initiation processes [13][14][15][16][17][18]. A method of stabilizing the vanadium active center, and in consequence, a prolongation of catalyst lifetime, is to apply ligands with electron-donating atoms-oxygen, nitrogen, or phosphorus [14][15][16][17][18][20][21][22][23][24][25][26][27][28].…”