Jiang Liansheng

Iron-based catalysts for conjugated dienepolymerization and the polymer properties

This review concerns the progress in the design and synthesis of iron-based catalysts for the polymerization of conjugated dienes and the properties of the produced polymers. The development of new transition metal-based catalysts for conjugated diene polymerization is a long-standing research subject since the diene polymers are the most important elastomers widely used in our modern life. As the most abundant transition metal in the earth’s crust, iron is an ideal candidate for application of catalysis from the viewpoint of economic and environmental benefits. While iron-based catalysts were known to polymerize conjugated dienes even in the late 1950s, they have not been extensively studied due to the low activity and poor selectivity. The recent discovery that late-transition metal catalysts are effective for ethylene polymerization and oligomerization rejuvenated the academic and industrial interests. Many efforts have also been made in the field of conjugated diene polymerization with iron-based catalysts, and it was found that addition of appropriate electron donors could improve the catalytic performance. As a result, a variety of iron-based catalysts with nitrogen- and phosphine-containing compounds as a ligand or a catalyst component were developed, and these catalysts exhibited high activity and selectivity in the polymerization of conjugated dienes. Polymers with versatile microstructures and tacticity have been synthesized from 1,3-butadiene, isoprene, and 1,3-pentadiene.