Effect of Cyclopentadienyl and Anionic Donor Ligands on Monomer Reactivities in Copolymerization of Ethylene with 2-Methyl-1-pentene by Nonbridged Half-Titanocenes−Cocatalyst Systems

Abstract

Copolymerization of ethylene (E) with 2-methyl-1-pentene (2M1P) took place with rather efficient 2M1P incorporation by using the Cp*TiCl2(O-2,6- i Pr2C6H3) (1)−MAO catalyst system, whereas the 2M1P incorporations by the Cp2ZrCl2, [Me2Si(C5Me4)(N t Bu)]TiCl2, Cp‘TiCl2(NC t Bu2) [Cp‘ = Cp (3), Cp* (4)], and Cp*TiCl3−MAO catalyst systems were negligible under the same conditions. The effects of substituents in both the cyclopentadienyl and the aryloxide ligands toward the catalytic activities and the 2M1P incorporations were explored, and use of both Cp* and 2,6-diisopropylphenoxy ligands was found to be important to obtain poly(ethylene-co-2M1P)s with rather efficient and uniform 2M1P incorporations as well as with notable catalytic activities. No distinct differences in the 2M1P incorporations were seen in the copolymerization by 1 in the presence of various cocatalysts [methylaluminoxane (MAO), methylisobutylaluminoxanes (MMAOs), borates], and the nature of ligands directly affects the 2M1P incorporation. Copolymerizations of ethylene with 7-methyl-1,6-octadiene (MOD) by 1,3,4−MAO catalyst systems proceeded at remarkable rates with efficient exclusive incorporation of monoolefins (without incorporating trisubstituted olefin), affording high molecular weight unsaturated poly(ethylene-co-MOD)s with high MOD contents. The MOD contents in the resultant copolymers in the ethylene/MOD copolymerization by 1,3,4−MAO catalyst systems were thus closely related to those in the ethylene/1-octene copolymerizations under similar conditions.

New Approaches in Precise Synthesis of Polyolefins Containing Polar Functionalities by Olefin Copolymerizations Using Transition Metal Catalysts

“…16 The MOD contents in the resultant copolymers were thus closely related to those in the ethylene/1 octene copolymerizations under the similar conditions.…”

“…A known classic model of this approach is the introduction of unsaturation as exemplifi ed by using 5 ethylidene 2 norbornene, 1,4 hexadiene, and dicyclopentadiene (but showed ineffi cient incorporations in the copolymerization by ordinary catalysts). 11,30 Introduction of unsaturated olefi nic double bond into the side chain can be possible by adopting the copolymerizatioin of ethylene with 7 methyl 1,6 octadiene (MOD, scheme in Figure 1), 16,31 especially due to a difference in the reactivity of two olefi nic double bonds (terminal vs trisubstituted). However, their incorporations by the ordinary catalysts (metallocenes etc.)…”

Microstructure of Copolymers of Norbornene Based on Assignments of 13C NMR Spectra: Evolution of a Methodology

“…[41][42][43][44][45] In particular, 4-methylcyclohexene (4-MeCHE) and 1-methylcyclopentene (1-MeCPE) copolymers have been synthesized recently with nonbridged half-titanocenes containing anionic donor ligands of type, Cp'TiX2(Y) (Cp' = cyclopentadienyl group, Y = aryloxo, ketimide, phosphinimide etc.) [46].…”

A Greener Approach for Synthesis of Functionalized Polyolefins by Introducing Reactive Functionality into Ethylene Copolymers

“…A known classic model of this approach is the introduction of unsaturation as exemplified by using 5-ethylidene-2-norbornene, 1,4-hexadiene, and dicyclopentadiene (but showed inefficient incorporations in the copolymerization by ordinary catalysts) [20] [31]. Introduction of unsaturatedolefinic double bond into the side chain can be possible by adopting thecopolymerizatioin of ethylene with 7-methyl-1,6-octadiene (MOD, Scheme 3) [29] [30] [32], especially due to a difference in the reactivity of two olefinic double bonds (terminal vs trisubstituted). However, their incorporations by the ordinary catalysts (metallocenes etc.)…”

“…However, their incorporations by the ordinary catalysts (metallocenes etc.) were inefficient, affording (co)polymers with low molecular weights as well as rather broad molecular weight distributions.We reported that copolymerizations of ethylene with 7-methyl-1,6-octadiene (MOD) by Cp*TiCl 2 (O-2,6-i Pr 2 C 6 H 3 ) (1)-MAO catalyst system afforded high molecular weight unsaturated poly(ethylene-co-MOD)s not only with high MOD contents, but also with exclusive incorporation of monoolefins (without incorporating trisubstituted olefin) [32]. The MOD contents in the resultant copolymers were thus closely related to those in the ethylene/1-octene copolymerizations under the similar conditions.…”