The Development of Photoinduced Initiation of Olefin Polymerization and its Applications

Polyolefin synthesis is an ever-growing field due to the low cost of monomer feed stocks and the wide range of applications of the resulting polymeric material. Polyolefins are most commonly polymerized through coordination-insertion polymerization. One area this field of research has progressed is the development of complex ligand scaffolds to achieve various levels of control over polymerization. For example, researchers have been able to control molecular weight, branching density, and tacticity of various olefin polymerizations. As a result of complex ligand scaffolds, the catalytic systems become more expensive and less industrially applicable. On the other hand, little research efforts have been made to activate current olefin polymerization precatalysts with the use of external stimuli.

Several methods of polymerization have harnessed the energy of light to initiate and control polymerizations. However, little progress has been made in the field of light mediated olefin polymerization. Therefore, several fundamental questions have emerged from this shortcoming: 1) can current light activated polymerization techniques be modified to activate olefin polymerization precatalysts? 2) If so, can the polymerization of both liquid and gaseous monomers be achieved through this method? and 3) Can light be used to gain spatial and temporal control over olefin polymerizations?

This dissertation seeks to address the current limitations in light mediated olefin polymerization through answering the presented fundamental questions. Specifically, we have developed methods in which UV light and visible light can be used to polymerize 1-hexene and ethylene in solution and facilitate the heterogeneous polymerization of ethylene. To do this we used a photoacid generator (PAG) or PAG/photosensitizer system in tandem with an olefin polymerization precatalyst. In addition, we showed that both temporal and spatial resolution can be achieved through this polymerization method. Following the developments in PIOP, I have provided my contributions to the synthesis and characterization of poly(cycloallenes) in Appendix C.