Efficient Molecular Weight Control with Trialkylaluminum in Ethylene/Norbornene Copolymerization by [Ph₂C(Flu)(3‐MeCp)]ZrCl₂/Methylaluminoxane Catalyst

Abstract

Ethylene/norbornene copolymerizations were conducted with [Ph2C(Flu)(3‐RCp)]ZrCl2 [R: Me (1) or Me3Si (2)], which give alternating EN copolymers. The activity of 1 in the absence of R3Al was approximately twice that of 2 and increased further upon addition of R3Al. Et3Al increased the activity most effectively, and the $\overline {M} _{{\rm n}} $ of the produced polymer decreased from 100 000 to 25 000 g · mol−1. On the other hand, the $\overline {M} _{{\rm n}} $ value increased upon addition of iBu3Al from 100 000 to 209 000 g · mol−1 accompanied by an ≈2.5‐fold increase of activity. Consequently, 1 was found to be one of the most promising complexes for the synthesis of alternating EN copolymers, of which $\overline {M} _{{\rm n}} $ value was efficiently controlled by the kind and the amount of R3Al added.magnified image

Copolymerization of ethylene with 1,1‐disubstituted olefins catalyzed by ansa‐(fluorenyl)(cyclododecylamido)dimethyltitanium complexes

“…Conversely, we have been studying the fluorenyl analogues of CGCs, Me 2 Si(η 3 ‐R)(N t Bu)TiMe 2 [R = fluorenyl ( 2 ), 2,7‐ t Bu 2 fluorenyl ( 3 ), 3,6‐ t Bu 2 fluorenyl ( 4 )] (Scheme ),7–9 as catalysts for olefin polymerization 10. These complexes 2 – 4 were found to be highly effective catalysts for homo‐ and co‐polymerization of higher α‐olefins11 and cyclic olefins such as norbornene 12–20. We assumed that the combination of cyclododecylamido and fluorenyl groups for titanium complexes should be useful to develop more effective catalysts for the polymerization of bulky 1,1‐disubstituted olefins.…”

“…10 These complexes 2-4 were found to be highly effective catalysts for homo-and co-polymerization of higher a-olefins 11 and cyclic olefins such as norbornene. [12][13][14][15][16][17][18][19][20] We assumed that the combination of cyclododecylamido and fluorenyl groups for titanium complexes should be useful to develop more effective catalysts for the polymerization of bulky 1,1-disubstituted olefins.…”

Ethylene-co-norbornene Copolymerization Using a Dual Catalyst System in the Presence of a Chain Transfer Agent

“…In each series, the same amount of TIBA was used as alkylating agent and as scavenger [41]. Although TIBA could also be considered as a possible chain transfer agent, in E- co -N polymerizations with ansa-zirconocenes activated by MAO as well as in propylene polymerization by ansa metallocenes activated with TIBA and tritylborate as cocatalyst, it was shown to have low or no tendency to exchange with Zr-polymeryl chains [45,46]. Selected results of copolymerization reactions performed at [N]/[E] ratios of 1.3, 4.8 and 26.0 at 70 °C are reported in Table 1, Table 2 and Table 3, respectively.…”

Kinetics, Mechanism and Theoretical Studies of Norbornene-Ethylene Alternating Copolymerization Catalyzed by Organopalladium(II) Complexes Bearing Hemilabile α-Amino–pyridine

“…These physical properties are usually controlled by the compositions and the microstructures of the monomers, resulting from the design of the catalysts [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. For instance, with the assistance of methylaluminoxane (MAO) [ 17 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ], most of the early-transition-metal metallocene derivatives catalyzed copolymerization to afford random E–N products. The ligand steric hindrance readily impedes the norbornene insertion, and thus the PE segments are usually long.…”