Gold-Catalyzed Upcycling of Aromatic Thermoplastics

Abstract Aromatic polymers are foundational to modern technologies; yet, their robust chemical and physical properties make them notoriously difficult to chemically modify, limiting their sustainable utilization and the development of emerging plastics technologies. Here, we introduce a postpolymerization modification strategy based on a gold-catalyzed, regioselective hydroarylation between commercial phenyl-substituted alkynes and the aromatic units of commodity, specialty, and engineering thermoplastics. This direct C–H activation enables the mild, chemoselective installation of 1,2-disubstituted alkenes bearing functionalized phenyl groups into amorphous and syndiotactic polystyrene, polysulfone, polyethylene terephthalate, poly(ether imide), and a semiaromatic polyamide, while preserving the inherent crystallinity and thermophysical properties required for high-performance applications. The exceptional functional group tolerance of gold enables the installation of functionality and reactive handles that are otherwise unattainable, while providing direct control over morphological, thermal, mechanical, and functional properties. This combination of preserved thermomechanical properties and newly introduced reactivity enables a distinct form of upcycling, in which existing polymer streams are transformed into higher-value functionally versatile materials. This platform overcomes long-standing synthetic limitations for aromatic polymer modification and upcycling, opening versatile routes to next-generation high-performance materials from existing polymer streams.