Theaker, Giles William (2010) tert-Butylstyrene in Ziegler-Natta polymerisations. PhD thesis, University of Warwick.

Abstract

Chapter One introduces Ziegler-Natta polymerisation through mechanisms of polymerisation encompassing activation, propagation and termination of a polymer. The mechanisms of monomer insertion and their effects on polymer microstructure are shown. Several important catalysts of different design (metallocenes, half-sandwich complexes and post-metallocenes) are shown. Chapter Two focuses on ethene/styrene and ethene/tert-butylstyrene copolymerisations using commercially available metallocene catalysts, with the goal of increasing styrenic co-monomer incorporation without sacrificing productivity. Terpolymers of the above systems with hexene are briefly discussed. Chapter Three looks at ethene/tert-butylstyrene copolymerisations using post-metallocene catalysts, focusing specifically on zirconium based salicylaldimine species. The dramatic effects of modified styrenic monomers on these catalysts is shown. Chapter Four shows how zirconium based salicylaldimine catalysts and similar species can be activated so as to homopolymerize tert-butylstyrene in the presence of H2 and other monomers. A mechanistic explanation of the effects is postulated. The effects of ligand modification are explored, leading to the discovery of the active species involved in the above homopolymerisations. Chapter Five covers experimental details relating to the above chapters, including synthesis of precursors, ligands, precatalysts and polymerisation methodologies.

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