Mild amorphization and structural reconstruction enable non-destructive recycling of continuous fiber-reinforced PAEK composites

Closed-loop recycling of PAEK composites via dynamic imination strategy. • Intractable PAEK is converted into a soluble amorphous intermediate. • Continuous fibers are non-destructively recovered with >95% strength retention. • The amorphous intermediate can regenerate into PAEK resin. • Recycled matrix retains pristine thermomechanical performance over multiple cycles. The recycling of high-performance fiber-reinforced PAEK composites is hindered by a paradox: the chemical inertness and crystallinity that provide exceptional stability also make their deconstruction extremely difficult, while conventional harsh methods irreversibly degrade both fibers and resin matrix. Herein, we report a targeted structural reconstruction strategy that enables the mild amorphization and closed-loop recovery of high-value composite components. With PEEK as a model, ZnCl 2 is utilized to catalyze the targeted imination of carbonyl groups. As verified by rigorous density functional theory (DFT) calculations, this specific coordination significantly reduces the kinetic activation barrier, enabling the disruption of the dense crystalline structure under extraordinarily mild conditions. Crucially, this crystalline-to-amorphous transition fundamentally overcomes mass transfer limitations, enabling the non-destructive extraction of continuous reinforcing fibers while retaining >95% of their pristine mechanical properties. After fiber separation, acid-catalyzed hydrolysis triggers structural reconstruction of the PEEK molecular backbone, largely restoring its original semi-crystalline morphology and key thermomechanical properties. This versatile recycling platform exhibits broad applicability across PAEK-based materials with diverse molecular architectures and maintains stable performance over three consecutive recycling cycles. This work provides a promising strategy with potential for further process development of high-performance PAEK composites.