High-Efficiency Mono-Cyclopentadienyl Titanium and Rare-Earth Metal Catalysts for the Production of Syndiotactic Polystyrene

Abstract

Syndiotactic polystyrene (SPS) refers to a type of thermoplastic material with phenyl substituents that are alternately chirally attached on both sides of an aliphatic macromolecular main chain. Owing to its excellent physical and mechanical properties, as well as its chemical stability, high transparency, and electrical insulation characteristics, SPS is used in a wide variety of technical fields. SPS is commonly produced via the stereoselective transition metal-catalyzed coordination polymerization method mediated by stereospecific catalysts, which consists of anionic mono-cyclopentadienyl derivative η5-coordinated single active metal centers (referred to as “mono-Cp’-M”), with active center metals involving Group 4 transition metals (with an emphasis on titanium) and rare-earth (RE) metals of the periodic table. In this context, the use of mono-cyclopentadienyl titanocene (mono-Cp’Ti) catalysts and mono-cyclopentadienyl rare-earth metal (mono-Cp’RE) metallocene catalysts for the syndiospecific polymerization of styrene is discussed. The effects of the mono-cyclopentadienyl ligand structure, cationic active metal types, and cocatalysts on the activity and syndiospecificity of mono-Cp’ metallocene catalysts are briefly surveyed.

Syndiotactic (Co)polymerization of 4-Vinylbenzocyclobutene Catalyzed by Rare-Earth Metal Complex

“…In the last two decades, precisely controlled polymerization of styrene and its derivatives had made significant progress by using rare-earth metal catalysts. − A variety of well-defined rare-earth metal catalysts sprung up, which showed high activity and perfect regioselectivity in both the homo- and copolymerization of styrene monomers. − The first examples of highly syndiospecific styrene polymerization mediated by rare-earth metal was reported almost simultaneously by the groups of Hou and Carpentier. , Cui’s group designed a series of constrained-geometry-configuration (CGC) type rare-earth metal complexes, which behaved well in styrene polymerization. ,− More interestingly, these complexes exhibited excellent performances in the polymerization of polar styrene monomers. ,− Isotactic polymerization of styrene monomers can be achieved by rare-earth metal catalysts as well. Carpentier et al first reported the highly isotactic polymerization of styrene initiated by rare-earth metal complexes in 2007 .…”