Selectivity in propene polymerization with metallocene catalysts

Metallocene catalysts emerge as a successful catalysts technology and represent the future of polyolefins. In the case of highly crystalline isotactic polypropylene (i-PP), despite a general belief, metallocene catalysts are far less active and efficient than the newest supported Ti/MgCl₂ catalysts. Metallocenes are use to make i-PP because i-PP properties are tailored. The full control over the degree of isotacticity means control over crystallinity and melting point, which allows the preparation of thermoplastic elastomers of varying degrees of crystallinity. The success of metallocene catalysts for propene-based polymers comes from the production of materials that cannot be made with heterogeneous catalysts.