CAS-SC: Tuning Hydrocarbon Products from Temperature-Gradient Thermolysis of Polyolefins and the Subsequent Upcycling to Functional Chemicals

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PART 1: NON-TECHNICAL SUMMARY Plastic waste is a global challenge that must be addressed to achieve a sustainable future. The PI has developed a technique of “cascade degradation and upcycling” (“Deg-Up”) that represents an emerging effective means to convert plastic waste into high-value chemicals and materials. In the degradation of the two most common high-volume commercial plastics made of polyethylene (PE) and polypropylene (PP), temperature-gradient thermolysis (a controlled thermal breakdown of the plastic molecules) is highly effective in converting them into platform intermediate chemicals for general uses. In the upcycling of platform intermediate chemicals, PE and PP-derived products are particularly useful for subsequent conversion to produce high-value materials such as surfactants (e.g., soaps, detergents, surface modifiers, etc.). The output of high-value surfactants from low-cost plastic waste can provide significant financial incentives to address the existing fast-accumulating plastic waste. The controlled “Deg-Up” of PE and PP, which will be the focus of this project, will offer new approaches to producing sustainable surfactants with reduced energy consumption and carbon emissions. Downstream functionalization of PE and PP-derived intermediate molecules will pave the foundation for the future development of “waste-to-value” using other plastic waste feedstocks. Highly integrated with the concept of “plastic sustainability”, the educational component of the project will train students at all levels including underrepresented local K-12 and college youth, work with neighboring Historically Black Colleges and Universities, and develop sustainable plastic waste removal programs in Appalachia. PART 2: TECHNICAL SUMMARY The vast amount of accumulated plastic waste requires a better ending point than landfills or oceans. Chemical upcycling is an attractive method to bring low-value plastic waste into high-value chemicals and materials. This project utilizes plastic waste as a chemical feedstock, much like “crude oil” except that it requires no drilling or mining. Two high-volume plastics, including polyethylene (PE) and polypropylene (PP), will be converted to high-value surfactants. The project will (a) provide an understanding of temperature-gradient thermolysis for producing controlled degradation intermediates and (b) develop upcycling strategies to produce value-added ionic and non-ionic surfactants. Three main research tasks of the project include: 1) employment of temperature-gradient thermolysis to degrade PE and PP, 2) functionalization of the thermolysis products with ionic end groups to form amphiphilic molecules for use as surfactants, and 3) functionalization of the thermolysis products into non-ionic molecules. The proposed research will impact the fields of polymers and surfactants and enable the upcycling of plastics into high-value chemicals. The upcycling strategy removes plastic waste, elongates the lifespan of carbon in a reduced form, decreases carbon emissions, and mitigates environmental pollution. The educational impacts include training underrepresented K-12 and first-generation college students in Appalachia. The educational components share the central theme of “polymer sustainability” and are highly integrated with 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.