Evolution of Ziegler-Natta catalysts for polymerization of olefins

Abstract

This chapter provides a brief account of the discovery and gradual evolution of Ziegler-Natta catalysts for polymerization of various olefins, α-olefins, and functional olefins. The structure of first and second generation catalysts is introduced, and the different mechanisms proposed by the scientists for the polymerization of ethylene using this catalyst is discussed. Subsequently, the control of branching and mechanism to produce stereospecific poly-α-olefins is elaborated. Development of catalysts for synthesis of stereo-controlled polyolefins is discussed along with methods to determine the stereospecificity of the polymers. The evolution of metallocene-based Ziegler-Natta catalysts and the mechanism of polymerization based on these catalysts are briefed. The following section discusses about the catalyst compositions useful for polymerization of functional olefin monomers and their copolymerization with propylene. Development of catalyst compositions based on Pd, Ni, Cu, and Fe is discussed, and subsequent polymerization mechanism is included. A series of catalysts synthesized using vanadium and various chelated ligands are discussed in context of their catalytic activity and the structure of polymer formed. The last chapter unveils some of the recent advances in these categories of catalysts and future scope of the catalyst.