Determining the Environmental Controls of Plastic Photodegradation Mechanisms

This award supports Professor Lauren Pincus at George Washington University to develop a predictive understanding of plastic (polyethylene, polystyrene, and polyethylene terephthalate) photo-oxidation rates and pathways. Photo-oxidative degradation of plastics involves a complex series of reactions initiated by UV-generated free radicals, which could result in molecular changes in plastic structure and surface chemistry with increasing concerns. The effects of free radicals produced and the role of water/humidity on formation of photo-oxidative intermediates and products remain poorly understood. Professor Pincus and her students will use advanced synchrotron spectroscopy/microscopy techniques to investigate the effects of free radicals on the intermediates and products, and better understand how water/humidity and nanoscale heterogeneity affect degradation of plastics. Their studies would advance the understanding of plastic degradation pathways and could support the design of better polymeric materials. This research will also support annual workshops with local non-profits to disseminate research results with interested community stakeholders. The overall goal of this research is to use controlled laboratory experiments paired with advanced spectroscopy techniques to determine the effect of key parameters on plastic (polyethylene, polystyrene, and polyethylene terephthalate) photo-oxidation rates and pathways. This study seeks to fill critical knowledge gaps to understand at a mechanistic and molecular level the role of external conditions on promoting and hindering specific photo-oxidative pathways. The novel contributions of this study will include: 1. Isolating and determining the effects of free radicals on the kinetics of photo-oxidation, as measured by both photo-oxidative intermediates and products; 2. Determining the mechanistic role of water/humidity in promoting or hindering plastic photo-oxidative intermediates and products, and 3. Use of advanced synchrotron spectro-microscopy techniques, to analyze nanoscale heterogeneity in plastic photo-oxidation. Through these contributions, this study will build a fundamental understanding of plastic degradation pathways at a mechanistic and molecular level, enabling predictions of how plastics degrade and in turn supporting the design of better polymeric materials. 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. NSF Award ID: 2603834 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Lauren Pincus | Institution: George Washington University, WASHINGTON, DC | Award Amount: $550,000 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2603834 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2603834.html