(154al) Upcycling of Waste Poly(vinyl chloride) (PVC) through Depolymerization Under Mild Conditions

Interest is growing in managing plastic wastes through depolymerization and upcycling. While certain commodity polymers like poly(ethylene terephthalate) (PET) have received a great deal of attention, poly(vinyl chloride) (PVC) has received much less attention. PVC has very large worldwide production volumes, while simultaneously being among the least recycled plastics. Undoubtedly, PVC has unique challenges associated with recycling, specifically, its propensity to undergo dehydrochlorination and crosslinking during thermomechanical recycling, and release of HCl. Here, we present options to manage and valorize PVC that take advantage of dehydrochlorination and enable depolymerization toward small molecules and oligomers that can be upcycled. Dehydrochlorinated PVC [DHPVC] with conjugated polyene segments was produced in our lab followed by catalytic hydrogenation at ambient temperature and relatively low pressures. This hydrogenation acts as a preparation step, as it greatly lowers (or eliminates) the presence of conjugated C=C bonds in the modified PVC, while simultaneously stabilizing it from oxidation and/or crosslinking. This hydrogenated dehydrochlorinated PVC [H₂-DHPVC] can then be cleaved via olefin metathesis catalysts to yield small molecules and oligomers. This presentation will discuss the benefits and challenges of working with PVC, as well as an overview of methods and target products.