Additive Manufacturing of Vitrimers with Circularity

Over 400 million tons of solid plastics are globally produced annually and only ~9% of those are currently recycled in U.S.. Establishing closed-loop circularity of plastics with a facile manufacturing path is critical for global circular economy. When commodity plastics are upcycled into higher-performance materials with facile processability, a sustainable closed-loop manufacturing would become reality. Additive manufacturing (AM) of such upcycled plastics to custom-designed structures accomplishes energy and resource efficient low-carbon closed-loop manufacturing. We hereby open a circular upcycling of a commodity plastic into a higher-performance vitrimer with fused deposition modeling or direct ink writing, resulting in robust printout properties comparable to crosslinked thermosets. Vitrimer exhibits mechanical robustness and chemical resistance because of its covalent network formation, but it can also be malleable by reconfiguring reversible crosslinks through the associative bond exchange at elevated temperature, making it recyclable. Due to its crosslinked nature, the upcycled vitrimers provide stronger, tougher, solvent-resistant 3D objects and separatable from unsorted plastic waste. Tailoring the vitrimer composition overcomes the major challenge of (re)printing crosslinked materials, allowing multi-cycle printing. This presentation updates our efforts on AM of upcycled commodity plastics, especially upcycled vitrimers.