Abstract
This review describes the olefin polymerization behavior of bis(phenoxy-imine) and bis(phenoxy-ketimine) early transition metal complexes (a.k.a. FI catalysts). FI catalysts display unique catalytic properties due to the coordination of a pair of non-symmetric, electron-withdrawing and reactive [O−, N] chelating ligands (FI ligands). Moreover, FI ligand structures can be readily tailored from the electronic and steric point of view. Thus, FI catalysts in combination with appropriate activators are capable of producing a wide variety of unique olefin-based materials (FI polymers). Specific examples of FI polymers include selective vinyl-terminated polyethylenes, ultra-high molecular weight linear polyethylenes, well-defined and controlled multimodal polyethylenes, ethylene/polar monomer copolymers, highly syndiotactic and isotactic polypropylenes with exceptionally high Tms, ethylene- and propylene-based end-functionalized polymers, a wide array of polyolefinic block copolymers from ethylene, propylene and higher α-olefins, and ultra-fine non-coherent polyethylene particles. These FI polymers display new or enhanced material properties, and to this end, several FI polymers are now entering the industrial phase.
