CAREER: Molecular Approaches for Understanding Defect-Porosity Relationships in Microporous Organic Polymers

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In this CAREER project, funded jointly by the Chemical Structure, Dynamics & Mechanisms-B (CSDM-B) program in the Division of Chemistry (CHE) and the Solid State & Materials Chemistry (SSMC) program in the Division of Materials Research (DMR), Dr. James Bour and his research team at Wayne State University are studying how imperfections in polymer structures affect polymer microporosity. Microporosity is an important property affecting the performance of polymers in applications such as water purification, gas storage, gas purification, energy harvesting, sensing, and catalysis, yet there are few design principles for controlling it. The goal of this project is to address this knowledge gap by exploring the hypothesis that defects strongly influence microporosity. Dr. Bour and his team aim to establish relationships between defects and porosity through the development of chemical reactions that allow quantification and simulation of potential defect structures. These studies have the potential to result in improved understanding of key structural features in high microporosity polymers. Insights gain will aid in the hypothesis-directed design of synthetic approaches to microporous polymers. In parallel with these studies, Dr. Bour will host a yearly state continuing education clock hour program in polymer chemistry for middle and high school teachers in Michigan. This activity is designed to interface directly with early science education mission in the state, helping to prepare the nation’s future workforce in polymer science. Owing to their high microporosity, structural diversity, and robust chemical stability, porous organic polymers have potential to address modern challenges in water purification, energy harvesting, gas storage/purification, catalysis, and sensing. Polymer porosity, and ultimately their performance in these targeted applications, is strongly affected by synthetic approach. However, little is known about why some reactions consistently and significantly outperform other synthetic strategies. This project aims to address this fundamental knowledge gap by studying how reaction-dependent defect structures impact bulk porosity. Spectroscopic interrogation of defects in microporous network polymers is historically challenging. This research will instead focus on determination of defect-porosity relationships through chemical methods. Network disassembly approaches specifically designed for the rigid structures of porous polymers will be used to characterize native defectivity in model polymers. Systematic relationships between defect incidence and structure will be determined through copolymerization of conventional monomers with defect-simulating or pro-defective monomers. Taken together, these studies are expected to establish quantitative relationships between defects and porosity metrics such as apparent surface area, pore volume, and pore size distribution. Insights gained will help guide the development of improved and more controlled synthetic protocols, particularly for high surface area microporous polymers.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.