Homogenous Gold Catalysis—A Versatile Platform for the Upcycling of Commodity Aromatic Polymers

Aromatic polymers are omnipresent and indispensable to the global economy and modern life. Green pathways for the post-consumer utilization of these materials, via recycling or chemical upcycling, remains a significant challenge as consequence of their intrinsically robust physical properties and recalcitrant aromatic C−H bonds. Here, we demonstrate that homogeneous gold (Au) catalysis offers a practical, mild, and chemoselective means to upcycle high-volume commodity aromatic polymers. Using a Au-catalyzed hydroarylation between a functional alkyne, methyl propiolate, and the arenes within polystyrene (PS) results in the installation of methyl acrylate functional groups onto virgin and waste PS. Methyl acrylate incorporation efficiency is modular as a function of the steric and electronic environment of the catalyst, ion pairing, and means of catalyst activation. The Au-upcycling protocol is broad in scope, allowing for the functionalization of commercial polysulfone and waste polyethylene terephthalate. The functionalized products exhibited significant changes to intrinsic physical properties such as glass transition temperature, modulus, melt viscosity, and wettability. These reactions provide a platform through which to extend the lifespan of commodity aromatic materials, and through which to leverage the unique reactivity of Au toward the upcycling of polymeric materials.