3D Printing of Recyclable Elastomers with Controllable Degradation and Adhesive Properties

Photopolymerization-based 3D printing is now a well-established manufacturing technique for a wide range of applications, as it allows the customized fabrication of objects with high resolution, tunable mechanical properties, and various functionalities. However, after printing, the crosslinked polymeric networks cannot be easily degraded and recycled, raising economic and environmental concerns. To date, only a few reprocessable or partially recyclable 3D printing resins have been reported. These resins are based on complex formulations or specific chemical structures. In addition to their high production costs and their limited scope of applicability, none of these materials can be completely depolymerized after photopolymerization 3D printing. Here, a general strategy is proposed to design degradable and recyclable photopolymers for 3D printing by taking advantage of the reversible aza-Michael addition reaction. With this approach, complete degradation of printed objects can be achieved under ambient conditions with tunable kinetics. The depolymerized products can be recycled and directly used for re-printing without the need of adding extra resins. Furthermore, using dopamine as a representative monomer, the possibility of incorporating additional chemical functions into the printed materials, such as adhesive properties, is demonstrated.