Neodymium Based Ziegler Catalysts - Fundamental Chemistry

Even though Ziegler catalysts have been known for almost half a century, rare earth metals (Ln), particularly neodymium (Nd)-based Ziegler catalyst systems, only came into the focus of industrial and academic research well afterthelargescaleapplicationoftitanium, cobaltandnickelcatalystsystems. Asadirectconsequenceofthelaterecognitionofthetechnologicalpotentialof rareearthmetalZieglercatalysts, thesesystemshaveattractedmuchattention. Considerable progress has been made in this ?eld as a result of intensive workperformed during the last fewyears. Worthmentioning is thestructural identi?cation of a variety of Ln/Al heterobimetallic complexes and the role of alkyl aluminum cocatalysts in molar mass control. Furthermore, a deeper understanding ofthe polymerization mechanism, suchas theliving character of neodymium-catalyzed diene polymerization associated with the reversible transfer of living polymer chains between Nd and Al, was revealed quite - cently. In spite of the vast number of patents and publications mainly issued duringthelastdecade, acomprehensivereviewthatcoversthescienti?caswell as the patent literature has been missing until now. In this volume we try to review the available literature by two independent approaches to Nd and Ln-catalyzed diene polymerizations. In the ?rst part of thevolume, whichisentitled"Neodymium-Based Ziegler/NattaCatalystsand their Application in Diene Polymerization", a polymer chemists view is given with strong emphasis on Nd-based catalyst systems. Also technological and industrialaspectsofNd-catalyzeddienepolymerizationsareaddressed.Inthe secondpartofthevolume, whichisentitled"Rare-EarthMetalsandAluminum Getting Close in Ziegler-type Organometallics", a more organometallic p- spective isgivenandLn-based catalystsystems areaddressed. Bythesynopsis of these different perspectives, the reader will comprehend the complexity of Ln-based Ziegler catalyst systems and their application to the polymerization of dienes. This volume also gives a description ofthe evolution in Nd-catalyzed po- merization of dienes from the early works to the current state of the art.