Shojiro Kaita

Novel polymerization and copolymerization of ethylene, styrene, and/or butadiene by new organolanthanide-based catalysts

Replacement of one of the two C5Me5 ligands in the samarocene (II) complex (C5Me5) 2Sm (THF) 2 with a monodentate anionic ligand (e. g. , OAr, SAr, or NR1R2) gives a unique catalytic system, which can not only polymerize styrene and ethylene, but also copolymerize them into block styrene-ethylene copolymers under the presence of both monomers. On the other hand, addition of an appropriate cocatalyst such as MMAO or AlR3/[Ph3C][B (C6F 5) 4] to the samarocene complex (C5Me5) 2Sm (THF) 2 or (C5Me5) 2Sm (m-Me) 2AlMe2 affords a novel catalytic system for stereospecific 1,4-cis living polymerization of butadiene and copolymerization of butadiene with styrene.

Synthesis of New Organolanthanoid Complexes and Their Use as Novel Catalysts for Polymerization and Copolymerization of Olefins

The replacement of one of the two C5Me5 ligands in the samarocene(II) complex (C5Me5)2Sm(thf)2 with a monodentate anionic ligand such as OAr, SAr, NR1R2, or CH(SiMe3)2 gave a unique catalytic system, which can not only polymerize styrene and ethylene, but also copolymerize them into block styrene–ethylene copolymers under the presence of both monomers. On the other hand, the addition of an appropriate cocatalyst such as MMAO or AlR3/[Ph3C][B(C6F5)4] to the samarocene complex (C5Me5)2Sm(thf)2 or (C5Me5)2Sm(μMe)2AlMe2 afforded a novel living catalytic system for stereospecific 1,4-cis polymerization of 1,3-butadiene and copolymerization of 1,3-butadiene with styrene.

Recent Developments of Organotransition-metal Catalysts for Polymerization: 3. Lanthanide Complex Catalysts for Diene Elastomers

Recently, Nd-based catalyst systems have been developed for the polymerization of butadiene, and have already been widely used in industrial applications. However, the 1, 4-cis selectivity and molecular weight distribution of the produced polybutadiene (BR) cannot be well controlled, since these catalyst systems are Ziegler-Natta based “multisite” catalysts. On the other hand “single-site” catalyst system, lanthanide-metallocene/cocatalyst system, has attracted recent interest as the next generation catalyst system, which can induce ultimately specific 1, 4-cis polymerization (>99.99%) and cis-specific living polymerization (sharp MWD). This article is a brief introduction of recent topics, including strategies aiming at these new elastomers based on tailor-made lanthanide-metallocene catalysts.