Circular 3D printing of high-performance photopolymers through dissociative network design

One approach for closed-loop plastics recycling relies on reverting polymers back into monomers because one can then make new plastics without loss of properties. This depolymerization requirement restricts the molecular design to making polymers with high mechanical performance. We report a three-dimensional (3D) printing chemistry through stepwise photopolymerization by forming dithioacetal bonds. The polymerized network can be transformed back into a photoreactive oligomer by dissociation of the dithioacetal bonds. This network-oligomer transformation is reversible, therefore allowing circular 3D printing using the same material. Our approach offers the flexibility of making modular adjustments in the design of the network backbone of a polymer. This allows access to fully recyclable elastomers, crystalline polymers, and rigid glassy polymers with high mechanical toughness, making them potentially suitable for diverse applications.