Burning Rubber Duckies With Flashlights: Applications of Photothermal Conversion to PVC Chemical Upcycling

Abstract

Poly(vinyl chloride), or PVC, is the world’s third-most produced thermoplastic but one of the least recycled materials. A deleterious tendency to release HCl (g) upon heating and high plasticizer content is among the most significant hurdles toward a more circular economy. Leveraging photothermal heating initiated by carbon black, this work productively utilizes this HCl (g) to functionalize styrene into (1-chloroethyl)benzene in up to 89 % yield with minimal side-products. This versatile product was further upcycled into 1-phenylethanol, a perfume additive and precursor to the commodity chemical acetophenone, as well as fendiline, a common heart medication. Crucially, the system proved highly tolerant of plasticizers and amenable to commercial samples in up to one-gram total loading without solvent processing. Additionally, the PVC system was able to hydro-chlorinate various olefins into the corresponding chloroalkanes in good yields. Finally, the dechlorinated carbon content of PVC, DHPVC, also found utility as a photothermal agent to depolymerize polystyrene, while further study of its photothermal capabilities revealed a new approach towards TiO2-catalyzed small molecule transformations. Overall, this work presents a novel strategy for tapping an overlooked portion of the plastic waste stream as a chemical feedstock in the hopes of better managing global PVC waste.