The Cover Feature shows an artistic interpretation of a supported polymerization catalyst particle that is fragmenting during ethylene polymerization. In their Research Article, F. Meirer, B. M. Weckhuysen and co-workers used high resolution X-ray electron microscopy to elucidate the origins sectioning fragmentation mechanism in two different silica-supported olefin catalysts at single level. o...

Strict morphological control over growing polymer particles is an indispensable requirement in many catalytic olefin polymerization processes. In catalysts with mechanically stronger supports, e. g., polymerization-grade silicas, the emergence of extensive cracks via sectioning fragmentation mechanism requires severe stress build-up polymerizing catalyst particle. Here, we report on three facto...

The new highly active supported vanadium-magnesium catalyst (VMC) has been studied in α-olefin (1-butene, 1-hexene)/ ethylene copolymerization in the presence of hydrogen. Data on the effect of α-olefin/ethylene ratio in copolymerization on the content of branchings in copolymers, kinetic profile, copolymer yield, molecular weight and molecular weight distribution of copolymers have been obtain...

The coordination polymerization of ethylene in water as a reaction medium was studied. Rubbery amorphous branched polyethylene was obtained when a known cationic diimine-substituted methyl complex was employed as a catalyst precursor. High rates of up to 900 TOh(-1) (turnover frequency) were observed. In contrast to solution polymerization in an organic solvent, the rate of suspension polymeriz...

Polyols are typically produced using batch processes and KOH as the dominant homogeneous catalyst. In this case, the main reaction is an ionic polymerization reaction, and products with narrow molecular weight distributions (MWDs) are typically obtained. As observed in living polymerization systems, polyols of varying molecular weights serve as starting points for manufacture of polyols of high...

A series of Cr(III) complexes based on quinoline-cyclopentadienyl ligands with additional hemilabile side arms were prepared and used as single-site catalyst precursors for ethylene polymerization. The additional donor functions interact with the metal centers only after activation with the co-catalyst. Evidence for this comes from DFT-calculations and from the differing behavior of the complex...

A group of readily available zirconium catalysts incapable of ethene-co-styrene polymerization are remarkably active and selective for the production of the new polymer ethene-co-tert-butylstyrene via a single site mechanism.

SUPERCRITICAL CO2 BY AN ELECTRON POOR NI(II) COMPLEX Damien Guironnet and Stefan Mecking* Chair of Chemical Materials Science, Department of Chemistry, University of Konstanz, Germany. Introduction Late transition metal catalysts for polymerization of olefins have been studied intensely. Due to their functional group tolerance, polymerizations can be carried out in oxygenated reaction media, am...

Nickel-based ethylene polymerization catalysts have unique features, being able to produce macromolecules with a variable content of branches, resulting in polymers ranging from semicrystalline plastics elastomers hyperbranched amorphous waxes and oils. In addition Brookhart’s α-diimine catalysts, iminopyridine Ni(II) complexes are among the most investigated systems. We report that bearing ary...