Upcycling of waste polycarbonate to recyclable Poly(carbonate-imines) with exceptional thermal properties and unprecedented flame retardancy

This study introduces an innovative method for upcycling waste polycarbonate (WPC) into poly(carbonate-imines) (PCIs), which exhibit exceptional thermal properties and unprecedented flame retardancy. Utilizing a novel insertion reaction of 2-((4-nitrophenoxy)methyl)oxirane with WPC, followed by hydrogenation, we have synthesized WPC-derived amine (WPC-NH2). This amine is further reacted with bifunctional aldehydes to form PCIs that not only meet vitrimer criteria (characterized by stress relaxation and thermal reprocessability through imine metathesis) but also demonstrate superior thermal stability (Tg up to 228 °C) and low thermal expansion (42 ppm/°C). Importantly, these PCIs achieve a UL-94 V-0 rating and exhibit significantly reduced total heat release (11.8 KJ/g), positioning them as prime candidates for sustainable, high-performance materials. The synthesis process supports recycling, showcasing a practical approach to the degradation of PCI-based CFRPs and recovery of intact carbon fibers, underscoring the environmental benefits of this method.