Incompatible polyolefins, such as polyethylene (PE) and polypropylene (PP), account for nearly two- thirds of the plastics produced worldwide and do not naturally decompose. Because of their incompatibility, they must go through an expensive sorting process before recycling. Unfortunately, limited by the low efficiency and high cost of the current recycling process, only 7% of PE and 3% of PP are currently recycled. Instead, most of them are dumped into landfills. A compatibilizer, functioning as a dispersant in the immiscible polymer mixture to enhance their compatibility, provides opportunities for recycling of incompatible polymers. Engi-Mat will develop a new type of compatibilizer to achieve high efficiency and low cost for recycling and upcycling of incompatible polyolefin types of polymers. This novel compatibilizer has polymers that can easily be tailored based on the composition, ratio, and molecular weight of the recycled polymers, which provides advantages relative to commercial compatibilizers that are currently available. Additionally, the new compatibilizer reinforces the polymer properties during the recycling process which further enables the upcycling of the recycled polymer. In Phase I, we will design and synthesize the novel compatibilizer, verify its ability to improve the compatibility of the immiscible polyethylene and polypropylene mixtures, prove the feasibility of this design through the total synthesis and evaluation of the compatibilizer, and create a more efficient and cost-effective polymer recycling and upcycling process. Our novel polymer compatibilizer will significantly improve the efficiency of polymer waste recycling and enable upcycling that provides value-added products for many industries. With its outstanding structural simplicity and flexibility to be tailored to a specific polymer requirement, this approach can overcome many limitations of the current recycling process. Besides supporting environmental protection, these results will improve energy efficiency and reduce Americaâs dependence on natural resources