Diverse Degradable Polymers from Versatile Ring-Opening Metathesis (Co)Polymerization of Electron-Rich Cyclic Olefins

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With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Yan Xia of Stanford University will develop new chemistry for generating new types of degradable plastics to address the grand end-of-life challenge of persistent plastics to the environment and human health. In 2018, 27 million tons of plastics were landfilled or released into the environment in the US and are nondegradable. New polymers that are strategically designed to be recycled, degraded, or depolymerized on demand are highly desirable for environmental sustainability as well as many technological and biomedical applications. This project integrates educational endeavors at several levels to raise the public awareness of plastic pollution and recycling, and recruit and cultivate pre-college students, especially underrepresented students in the Bay Area, for future STEM careers. The research also provides perfect examples to interface organic chemistry, polymer science, and sustainability in undergraduate and graduate curriculum.Ring-opening metathesis polymerization (ROMP) of cyclic alkenes is a widely used method to synthesize controlled functional polymers. Enol ethers with an electron-rich alkene have long been believed to deactivate the catalysts for ROMP and routinely used to quench the polymerization. But the Xia laboratory discovered surprisingly efficient ROMP of cyclic enol ethers and their copolymerization with strained cyclic alkenes, leading to new types of degradable polymers with acid labile backbones. This research project will explore the metathesis chemistry of electron-rich heteroatom-substituted cyclic alkenes and their copolymerization for the first time, and understand how the thermodynamic and kinetic parameters impact the control, microstructures, degradation profiles, and physical properties of the resulting degradable/depolymerizable 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.