New approach to block copolymerization of ethylene with polar monomers by the unique catalytic function of organolanthanide complexes

Katalysatoren für die lebende Insertionspolymerisation von Alkenen: mit Ziegler-Natta-Chemie zu neuartigen Polyolefin-Architekturen

“…[49] Yasuda et al berichteten auch¸ber divalente Samariumkomplexe mit verbr¸ckten Bis(Cp)-Liganden (Cp Cyclopentadienyl), die sie zur Polymerisation von Ethen einsetzten. [51] F¸r entsprechende trivalente Lanthanoidkomplexe mit verbr¸ckten Bis(Cp)-Liganden wurde keine hˆhere Polymerisationsaktivit‰t beobachtet. Die entstandenen Poly(a-olefine) waren hoch isotaktisch (z.…”

The synthesis and X-ray structure of a phenoxyimine catalyst tailored for living olefin polymerisation and the synthesis of ultra-high molecular weight polyethylene and atactic polypropylene

“…After Doi's pioneering contributions, different metal complexes were used as catalysts for living olefin polymerisation, including bridged lanthanide cyclopentadienyl complexes [15][16][17][18], cobalt half sandwich complexes [19,20], niobium diene complexes [21] and nickel-a-diimine complexes [22]. Yasuda et al managed to synthesise block copolymers of ethylene and polar comonomers in which the polymerisation mechanism changes during the reaction [23].…”

Developments of rare earth metal catalysts for olefin polymerization

“…Although the activities of these complexes were Scheme 3. rather low ($0.3 kg(mol of catalyst) À1 h À1 ), both complexes gave highly isotactic polymers. The divalent rac and meso complexes promoted ABA-type triblock copolymerization of ethylene with polar monomers such as MMA and e-caprolactone [33]. The rac complex 24 should enable triblock copolymerization of a-olefins and polar monomers.…”

“…The corresponding yttrium alkyl and hydride complexes, (C 5 Me 4 SiMe 2 NBu t )Y-(CH 2 SiMe 3 )(THF) (31) and [(C 5 Me 4 SiMe 2 NBu t )YH-(THF)] 2 (32), also shows low activities for ethylene polymerization to give linear polyethylene [36]. A n-hexyl derivative, [(C 5 Me 4 SiMe 2 NBu t )Y(C 6 H 13 )(THF)] 2 (33), are effective for styrene polymerization to give syndiotactic-enriched polymers with narrow molecular weight distributions. A recent patent reported cationic alkyl species of scandium having Cp-amine ligands, [(C 5 Me 4 CH 2 CH 2 NMe 2 )Sc(alkyl)] + , are effective for catalytic olefin polymerization [37].…”