טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentElkin Tatyana
SubjectDesigning Octahedral Group 4 Complexes as Catalysts for
Polymerization Processes
DepartmentDepartment of Chemistry
Supervisor Professor Moris Eisen
Full Thesis textFull thesis text - English Version


Abstract

_Polyolefins, such as polyethylene and polypropylene are one of the most vital commodity chemicals consumed in daily life. The microstructure of the polymer influences its physical properties and allows various applications according to these features. The generation of the polymers is facilitated by use of catalysts based on group 4 metals of the periodic table. The understanding of catalyst structure relationships with the microstructure of the final polymer is crucial in order to understand the mechanism of action of the catalytic system, and to allow specific design of the catalyst to generate the polymer with the desired characteristics. In this work, we present the development of group 4 bis(amidinate) complexes as potent catalysts for the polymerization of olefins and cyclic lactones. The effects of electron withdrawing and electron donating groups has been investigated. Additionally, the effects of the introduction of additional electron donating pendant arms into the ligand framework demonstrated a strong relationship between the nucleophilic parameter of the pendant moiety and the stereoregulation of the polymerization. The more nucleophilic arms were shown to produce highly isotactic polypropylene, however in lower yields.

The bis(amidinate) group 4 complexes have also demonstrated the ability to polymerize caprolactone. The more nucleophilic arms have demonstrated slower polymerization rates in this case as well.