NSF Award
2204079
With the support of the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry, Professor Junpeng Wang at the University of Akron is developing mechanically active degradable polymers. Polymers, commonly referred to as plastics, are long-chain macromolecules that consist of predominantly carbon-carbon bonds. Plastics that can degrade in response to external stimuli are desirable for a variety of applications, including removable coatings, recyclable materials, and repairable electronics. Their degradation is typically enabled by the cleavage of degradable functional groups that are incorporated in the polymer backbone. However, degradable functional groups can also lead to stability issues as they can be triggered under ambient conditions. This project will encompass the design and synthesis of a family of polymers that address the stability issues by introducing “locking” moieties to degradable polymers. A locking moiety will maintain the backbone integrity and mechanical properties of the polymer during storage and normal use of the materials. When degradation is needed, the locking moiety will be unlocked to enable stimuli-responsive degradation. From the sustainability point of view, the design principle associated with this project provides a very promising and viable solution to the current challenges associated with the widespread usage of non-degradable vinyl plastics. Hence, the developed methodology could be utilized to build readily degradable plastics that are amenable to a circular economy. This in turn could decrease demand for fossil fuels, such as oil, gas, and coal, which are the raw materials for over 99% of plastic commodity products. Since the refining of fossil fuels is intensive, a significant reduction in the emission of greenhouse gas could also be achieved. This project will provide training opportunities for students in a highly interdisciplinary area that integrates cutting-edge physical organic chemistry, organic and polymer synthesis, and mechanochemistry. The research will also ensure maximum opportunity for integrating science and education based on new course development, partnerships with high schools, and the involvement of underrepresented groups. Outreach activities will focus on developing recruiting relationships with Historically Black Colleges and Universities (HBCUs) in Ohio and preparing an exhibition “Polymers and Life” in collaboration with Akron Children’s Museum. <br/><br/>This project will focus on the design and synthesis of a class of polymers that can undergo a two-step degradation fashion: mechanochemical activation followed by degradation. This degradation mechanism will allow the degradation of the polymers to be controlled by mechanical force and will improve overall polymer stability while retaining optimal physical properties. In the first objective, the reactivity of the mechanophores will be tuned through substituent effects, stereochemistry, regiochemistry, and sidechain effects. This approach will provide mechanochemical structure–activity relationships that can guide the design and development of next-generation stimuli-responsive functional polymers. The second objective will focus on diverse degradation responses, including multi-stimuli responsive degradation, catalytic depolymerization, and chemically amplified degradation. The obtained results will enable the system to be coupled to a broad range of applications, such as controlled drug release, recyclable materials, as well as responsive surface and interface. In the third objective, the mechanically active degradation will be demonstrated in both solution-phase and bulk materials, which will provide important insights into stress distribution in polymers. Moreover, this design can be leveraged to convert thermosets into thermoplastics through mechanically activated degradation. New chemistries associated with this project have the potential to enable efficient recycling/upcycling of plastics and advance understanding of polymer mechanochemistry.<br/><br/>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.
