CAREER: CAS: Properties of Degradable Carbon Dioxide/Olefin Copolymers

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NON-TECHNICAL SUMMARY:Polymer sustainability is impacted by both the chemical feedstocks used in its production and the disposal of the material. The majority of plastics are synthesized from olefins, feedstocks which can be derived from petroleum or renewable resources. However, these polyolefins are durable materials and have contributed to an accumulation of plastic waste, thereby threatening the global environment and national interests. This work describes the inclusion of carbon dioxide into the polymer structure and the impacts this manipulation has on the durability and properties of the materials. By using carbon dioxide as a feedstock, the polymers have the potential to consume greenhouse gas as opposed to generating emissions. In addition, the incorporation of carbon dioxide into the polymer chain imparts degradability and chemical recyclability. The fundamental issue this project addresses is the development of an in-depth understanding of how the structures of these polymers affect their performance. Furthermore, the project expands research participation by engaging various student age groups and demographics with targeted graduate, undergraduate, and high school research projects. Educational programs on recycling will be implemented with local public schools in order to improve public understanding of plastic waste management and sustainable practices. These activities will include why plastics are used, how they are recycled, and also enable students to design and make repurposed plastic objects.TECHNICAL SUMMARY:The objective of this sustainability-focused project is to address the challenges in controlling the thermal and mechanical properties of copolymers derived from olefins and carbon dioxide. The results of this project will advance the synthesis of degradable copolymers of 1,3-butadiene and carbon dioxide in order to manipulate the microstructure, stereochemistry, and functionality. The branching of the polymer microstructure will be varied as a function of the conjugate-addition and ring-opening propagation mechanisms. Stereoselective catalysis will impart tacticity to the polymer chains which will be characterized spectroscopically. Orthogonal post-polymerization modification of the densely functionalized structure is proposed to generate a diverse range of products from a single material platform. Systematic synthesis of the above materials and quantifying their thermal and mechanical properties will enable a detailed understanding of the structure-property relationships. The research plan merges methods of polymer synthesis with spectroscopic and computational techniques in order to acquire a holistic understanding of the polymer chain dynamics and surface interactions. The outcomes will empower control over the thermal and mechanical properties for designing useful polymeric materials closely relevant to sustainability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.