Polymer support of “single-site” catalysts for heterogeneous olefin polymerization

The discovery of metallocenes and post-metallocenes has revived olefin polymer chemistry as these single-site catalysts enable the production of (co)polyolefins with tunable molecular structures, stereochemistries and molecular weight distributions. To be used in industry, however, such catalysts have to be manipulated under conditions already common to existing polyolefin production processes. This means, in particular, that their heterogenization is required to produce beads of polyolefins and prevent reactor fouling, and this in turn leads to the use of supports for these catalysts. The large majority of supports currently used in industry are inorganic-based, with silica being the most important. Organic supports are also of interest as they are expected to be more versatile and less expensive. This review presents a detailed survey of the different routes to immobilizing single-site catalysts on organic supports. The various methods as well as the different types of supports are described. The influence of the organic support on the catalytic activity and main features of the thus formed polyolefin viz. molecular weight, dispersity and morphology, are also considered.