CAREER: Molecular-level Understanding of Conductive Polymer Properties

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NON-TECHNICAL SUMMARY:Understanding how electricity and charged species (ions) flow through polymer materials is necessary to support the development of materials for improved water treatment technologies, chemical sensors, and batteries. Certain charged polymers are interesting in this area because they both conduct electricity and undergo electro-chemical reactions to bind ions from solutions. Theoretically, with improved understanding and refinements, charged polymers in this class could conduct electricity as well as metals, and store as much charge as materials used in lithium-ion batteries. But currently, these materials fall short of these theoretical limits. To date, scientists do not fully understand the fundamental factors limiting these polymers from achieving their theoretical potential. In this project, researchers at the University of Missouri will work to understand the molecular origins of electronic and ionic conductivity in these charged polymers. To accomplish this, University of Missouri researchers will use a new way of making these polymers that allows for the rapid generation of precisely controlled sequences of molecular building blocks (monomers) within the polymer chains. They will measure how different monomer sequences lead to interaction effects between monomers and drive changes in the flow of electrons and ions. This research will fill a critical gap in understanding the molecular-scale origins of electronic and ionic conductivity in charged polymers and is expected to help researchers develop improved materials for a range of applications including water treatment, chemical sensors, and battery technologies. These research activities will be complemented with the development of hands-on interactive learning modules to make the concepts surrounding the flow of electrons and ions through polymers tangible and engaging for elementary school students.TECHNICAL SUMMARY:This project will establish structure-property understanding connecting local and short-range (5 nm) structure of conjugated hetero-atom-containing copolymers with their electronic and ionic conductivity. Researchers will employ gas-phase oxidative molecular layer deposition (oMLD) synthesis to control the monomer sequence within copolymers containing two or more monomers of pyrrole, thiophene, furan, aniline, and related monomers, coupled with in situ characterization to monitor electrical properties during synthesis and chemical post-processing. Ex situ synchrotron and electron microscopy measurements will provide further insights into molecular structure origins of observed electronic and ionic transport properties. This project's overall goals are to: (1) understand mechanisms of electronic transport along copolymer chains, (2) understand mechanisms of anion transport through varying polymer coordination sites, and (3) engage the public and inspire young scientists with polymer research.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.