Chemical Recycling for Polycarbonates Mediated by Spirocyclic Acetal Trigger.

Plastic waste, particularly BPA-polycarbonate (BPA-PC), poses environmental and health concerns owing to its nondegradability and limited recyclability. Herein, we first reported a recyclable polycarbonate based on structurally rigid and acid-sensitive spirocyclic acetal units, which exhibited excellent mechanical properties and transparency. The use of biosourced vanillin as a multifunctional building block achieved a circular life cycle for the chemical materials. The copolycarbonates exhibited a high glass transition temperature (≥143 °C) and tensile strength (≥57 MPa), comparable to those of BPA-PC. Under mild acidic conditions (pH ≈ 6), the acetal linkages were selectively cleaved while carbonate groups remained intact, yielding telechelic polymers with aldehyde termini. These degradation products were efficiently reconverted to the original copolycarbonates, closing the loop for chemical recycling. This strategy offered a sustainable pathway toward a circular polycarbonate economy.