Doctor of Philosophy
Prof. Paul J. Ragogna
Metal containing polymers (metallopolymers) bring together the synthetic efficiency and versatility of conventional organic polymers with unique redox, responsive, and catalytic properties of inorganic metals. Over the last decade, metallopolymers have gained increased attention because of their unique physical and chemical properties that arise from the incorporation of metal centers into a polymer. Since the first report on a metallocene-based metallopolymer in 1955, there has been growing interest in this class of material. Ferrocene-based metallopolymers represent the vast majority of metallocene containing polymers in the literature. In 1992, the Manners Group established a major milestone in the field of metallopolymers by reporting the ring opening polymerization (ROP) of the strained silaferrocenophane to synthesize polyferrocenylsilane (PFS). The novelty of PFS has attracted attention to incorporate other metallocenes into polymer chains. In comparison to well-studied ferrocene containing polymers, cobaltocene have received far less attention due to the difficulties in preparing its derivatives. In fact, only a few key contributions on this subject have been reported. Cobaltocene with 19 electrons is not stable and is readily oxidized to a cationic 18 electron cobaltocenium. The Tang Group has developed a synthetic methodology to synthesize highly pure cobaltocenium derivatives and incorporated them into well-defined polymers.
Alternatively, the Ragogna Group reported the first neutral side-chain η5-cyclopentadienyl-cobalt-η4-cyclobutadiene (CpCoCb) functionalized metallopolymer. This mixed sandwich metallocene is an 18 electron complex, electronically neutral and isoelectronic to ferrocene and cobaltocenium. In this dissertation, the synthesis of well-defined side-chain functionalized CpCoCb containing homo- and block metallopolymers via reversible addition fragmentation transfer (RAFT) polymerization is detailed. Development of a controlled polymerization method to obtain well-defined high molecular weight CpCoCb containing metallopolymers is discussed. Several block copolymers were prepared via sequential RAFT polymerization. Synthesis, characterization, solution and solid-state self-assembly of the metal containing block copolymers is discussed in detail. These materials are used as ink in soft lithography to transfer patterns using a polydimethylsiloxane (PDMS) stamp. Synthesis of a series of CpCoCb monomers where the Cb ring is decorated with different substituents such as ferrocene and thiophene is reported. These highly metalized monomers are used to make metal rich materials with tunable metal content.
Hadadpour, Mahboubeh, "Exploring the Chemistry of η5-Cyclopentadienyl-Cobalt-η4-Cyclobutadiene Containing Polymers; Synthesis, Properties, and Self-Assembly" (2015). Electronic Thesis and Dissertation Repository. 2860.