Syndiotactic-specific polymerization of styrene: catalyst structure and polymerization mechanism

The mechanistic investigation of syndiotactic-specific polymerization of st yrene is reviewed, mainly with reference to the research work carried out a t the University of Salerno. NMR analysis of the stereochemical structure o f s-PS macromolecules, in some cases suitably labelled, provided valuable i nformation concerning the regiochemistry of polyinsertion, the type of addi tion to the monomer double bond, and the model of stereospecific propagatio n. Kinetic studies and spectroscopic investigation of the catalytic systems suggested a cationic Ti(III) complex with a strongly pi-co-ordinated benzy l-type growing chain as the true active species.