Photocatalytic Defluorination of Perfluorooctanoic Acid by Twisted Linear Polymer Radicals

Abstract

The exceptional persistence of per- and polyfluoroalkyl substances (PFAS) rooted in inert C–F bonds demands remediation strategies beyond energy-intensive treatments. Here, we report a bithiophene–fluorene–pyridine (BT–Fl–Py) linear polymer that achieves quantitative defluorination of perfluorooctanoic acid (PFOA) under visible-light irradiation. Upon photoexcitation, the polymer undergoes configurational torsional relaxation of the fluorene π-bridge, forming a stable twisted intramolecular charge-transfer state (TICT1) that stabilizes photogenerated electrons in a long-lived reducing state. Concurrently, the hydrophobic polymer backbone enriches PFOA, activating C–F bonds and facilitating efficient interfacial electron transfer. The cooperation between conformationally regulated charge separation and interfacial substrate enrichment enables complete PFOA defluorination under mild conditions, establishing a sustainable route for degrading ultrastable PFAS and providing a molecular design principle for developing reducing polymer photocatalysts.