Photocurable Double Dynamic Polyester Resins with Closed-Loop Circular End of Life

Circular acrylate-free photocurable resins are demonstrated based on a double-dynamic system combining disulfide and ester bonds. Aliphatic polyesters are functionalized with biobased lipoic acid (LA) and combined with a low-molecular-weight linker to produce a library of photocurable resins with tunable properties. Upon UV curing, ring opening of LA generates crosslinked networks featuring a polyester backbone and dynamic disulfide crosslinks. The materials exhibited excellent reprocessability, maintaining good mechanical performance over two thermal reprocessing cycles. In addition, closed-loop chemical recyclability of the twice-reprocessed materials was demonstrated under mild conditions, with recovery of the original photoreactive resin components in yields exceeding 85%. Lastly, a short degradation study under accelerated conditions indicated that the networks were degradable through hydrolysis. This work provides a versatile platform for circular photocurable resins with tunable properties, mechanical and chemical recyclability, and enhanced degradability, highlighting the importance of molecular design for circular polymer systems.