Upcycling Waste Polycarbonate to Poly(carbonate imine) Vitrimers with High Thermal Properties and Unprecedented Hydrolytic Stability

Upcycling of waste polycarbonate to poly-(carbonateimine)vitrimers (PCIs), aminolysis degradation, and unprecedented acid resistanceof PCIs in 5 M H2SO4. The global market for polycarbonate (PC) increases steadilybecauseof its heat resistance, toughness, and optical transparency. To achievesustainability, the waste polycarbonate (WPC) should be recycled.This work reports a 100% atom-efficiency upcycling of WPC to a WPC-derivedaldehyde (WPC-CHO). Then, poly-(carbonate imine) vitrimers (PCIs) basedon the WPC-CHO and two aromatic diamines were prepared. Generally,polyimines can cleave in mild acidic conditions such as 0.1 M HCl(aq) and seldom show good thermal and tensile properties. ThePCIs in this work showed good thermal and tensile properties and anunprecedented resistance toward acid hydrolysis. They can surviveeven immersing in a 5 M H2SO4 THF/H2O solution for 6 months. This unusual resistance toward acid hydrolysisexpands the application of PCIs in an acidic environment. Small piecesof PCIs can be compression-molded into a newly formed polymer filmat 240 degrees C. This thermal reprocessability demonstrates the vitrimercharacteristic of the PCIs. The PCIs can be degraded through simultaneousaminolysis of carbonate and transimination of imine by hexylamine(HA) in a catalyst-free mild condition. Based on the aminolysis andtransimination, we degraded the cross-linking network in the PCI-basedcarbon fiber-reinforced polymer (CFRP) and recovered undamaged carbonfiber. This environmentally friendly work will attract the attentionof researchers who are interested in sustainability and circularity.