Influence of Trialkylaluminum Reagents on the Propylene Polymerization Behavior of Bridged and Unbridged 2-Arylindene Metallocene Polymerization Catalysts

Abstract

Trialkylaluminum reagents such as triisobutylaluminum (TIBA) and trimethylaluminum (TMA) influence the propylene polymerization behavior of methylaluminoxane (MAO)-activated dimethylsilyl[bis(2-phenylindenyl)]zirconium dichloride (1). TIBA selectively decreases the productivity of the meso diastereomer of 1 (1-meso). This is manifested in an increase in the isotacticity of polypropylene blends prepared from mixtures of 1-rac and 1-meso compared to polymer blends prepared in the absence of TIBA. In contrast, added trimethylaluminum decreases the productivity of both 1-rac and 1-meso. Similar trends in reactivity with AlR3 are observed for unbridged bis(2-phenylindenyl)zirconium dichloride (2) compared to a mixture of the bridged catalysts containing 57% 1-rac. Mechanical testing indicates that polypropylene from 2 has superior elastomeric properties to reactor blends prepared from mixtures of 1-rac and 1-meso in the presence and absence of trialkylaluminum reagents. Reactor blends prepared without AlR3 exhibit poorer recovery at 100% and 300% strain than that of the elastomeric polypropylene from 2. The reactor blends prepared in the presence of TIBA exhibit pronounced yielding and necking during testing, characteristic of a softened plastic.

Anion Effects on the Activity and Stereoselectivity in Propene Polymerisations Catalyzed by C2‐Symmetric and “Oscillating” Catalysts

“…In the absence of both C 6 H 4 F 2 and TIBA, (PhInd) 2 ZrMe 2 /[Ph 3 C][B(C 6 F 5 ) 4 ] in neat toluene gave PP with lower isotacticity, 13.2%, so that it can be concluded that the slight changes in solvent polarity due to C 6 H 4 F 2 do not lead to a significant reduction in stereoregularity. The results agree with Waymouth's observations [28] that TIBA increases the isospecificity of 9 by an as yet unknown mechanism.…”

Using alkylaluminium activators to tailor short chain branching distributions of ethylene/1-hexene copolymers produced with in-situ supported metallocene catalysts

“…1 (runs 1a-3a) and a summary of all runs performed is shown in Tab. [10] Others have also observed that TIBA produces higher molecular weight polymer when used with homogeneous metallocenes [12][13][14] and supported metallocene catalysts. These runs were carried out under similar polymerization conditions and limited to low polymer yields to minimize the drift in comonomer concentration.…”

Furyl‐Substituted Group‐4 Metallocene Catalysts for Elastomeric Polypropylene Formation—The Role of the Remote Substituents

“…The typical Table 2 lists selected characteristic parameters from these series of experiments. These show in general that elasticity moduli in the expected range of elastomeric polyolefins were obtained 12 and that rather large elongations could be achieved before breaking of the polymer samples occurred. The individual polymers in this series showed quite remarkable differences, though.…”