Loop 3D printing: recyclable photoresins for light-mediated additive manufacturing

Additive manufacturing (AM) of polymeric materials has allowed the manufacturing of complex structures for a wide range of applications. Among AM methods vat photopolymerization(VP) techniques are desired owing to their improved efficiency and printing resolution. Nevertheless, the major portion of resins available for VP are based on systems with limited or negligible recyclability. Here, we develop an approach that enables the printing of a resin that could be re-printed with retained properties and appearance. To that end, we take advantage of the potential of polythiourethane chemistry, which not only permits the “click” reaction between polythiols and polyisocyanates in the presence of organic bases, allowing a fast printing process, but also chemical recycling, reshaping and reparation of the printed structures, paving the way toward the development of truly sustainable recyclable photoprintable resins. We demonstrate that this closed-loop 3D printing process is feasible both in the macroscale and microscale via DLP or DLW respectively.