Master of Science
Gilroy, Joe B.
This thesis outlines the synthesis and characterization of a stable organic radical homopolymer incorporating nitronyl nitroxide radicals, as well as the synthesis and characterization of random and block co-polymers incorporating nitronyl nitroxide and 6-oxoverdazyl radicals.
The nitronyl nitroxide homopolymer was synthesized using ring-opening metathesis polymerization (ROMP), yielding polymers with controlled molecular weights and narrow molecular weight distributions. Studies of polymer growth as a function of time and monomer:catalyst ratio revealed the ROMP to be well-behaved. Spectroscopic analysis of the polymer showed that the radicals possessed high radical content, indicating that they are tolerated by ROMP. Conductivity studies of thin-films made of the nitronyl nitroxide polymer were performed, exhibiting memory effects.
The nitronyl nitroxide and 6-oxoverdazyl random and block co-polymers were also synthesized using ROMP. It was found that the order of polymerization was key towards generating the block co-polymers. The co-polymers were fully characterized using spectroscopic, thermal, and electrochemical methods. Both radicals were incorporated into the co-polymers, and it was found that there was slightly more nitronyl nitroxide incorporation into the polymers than expected, which was attributed to its faster reaction rate.
Overall, this work examines the implementation of stable radicals into polymers, while also probing their behaviour as the functional component of solid-state electronics.
Summary for Lay Audience
Polymers are large molecules, called macromolecules, which themselves are composed of smaller molecular building blocks, deemed monomers. Polymers are found everywhere in day-to-day life ranging from the proteins in your body, to the plastic on your laptop. Scientists are actively searching for polymers with new applications to provide uses to our society. They do this by changing the chemical compositions that polymers have. By altering the composition, the physical (flexibility, toughness) and chemical (reactivity, toxicity) properties change. Some of this work has led to the production of functional polymers, polymers which change according to their surrounding environment. One such example is stable radical polymers. Radicals are molecules which are inherently very reactive species, however, fine-tuning of the structures of the molecules has led some examples to become stable enough to be used in polymers. One unique ability that stable radicals possess is their ease in gaining or losing electrons, which led them to be of interest for their application in electronics. For example, they have seen great potential in the use in organic batteries and solid-state devices such as flash memory (i.e., USB flash drives). The work in this thesis focuses on expanding on the field of stable radical polymers. New examples were made in this work and are presented. The performance of a flash memory produced from a stable organic radical polymer as the functional component is also described.
Anghel, Michael, "Synthesis of Stable Organic Radical Homo- and Co-Polymers and Their Applications in Solid-State Devices" (2020). Electronic Thesis and Dissertation Repository. 7411.
Available for download on Saturday, October 01, 2022