Electrochemical Postmodification of Polystyrene via Aromatic C-H Iodination

Postmodification of commodity polymers offers a promising route to mitigate environmental issues while creating value-added materials. Herein, we report an efficient and mild electrochemical strategy for the aromatic C-H iodination of polystyrene, affording iodinated polystyrene as a versatile macromolecular intermediate through anodically generated I⁺ species as a clean reagent for electrophilic aromatic substitution. The method enables direct iodination of polystyrene with a high degree of functionalization while nearly preserving the degree of polymerization and the narrow molecular weight distribution of the starting polymers, featuring selective modification at the aromatic moiety. Moreover, the strategy shows broad applicability to polystyrene substrates of various molecular weights as well as real-life waste such as expandable polystyrene and plastic spoons. Mechanistic studies were also conducted, disclosing a possible reaction pathway. By combining operational simplicity, environmental friendliness, and application potential, this strategy provides a practical and sustainable route for the up-cycling of polystyrene waste.