Three‐dimensional (3D) printing and especially VAT photopolymerization leads to cross‐linked materials with high thermal, chemical, and mechanical stability. Nevertheless, these properties are incompatible with requirements of degradability and re/upcyclability. We show here that thionolactone and in particular dibenzo[c,e]‐oxepane‐5‐thione (DOT) can be used as an additive (2 wt %) to acrylate‐based resins to introduce weak bonds into the network via a radical ring‐opening polymerization process. The low amount of additive makes it possible to modify the printability of the resin only slightly, keep its resolution intact, and maintain the mechanical properties of the 3D object. The resin with additive was used in UV microfabrication and two‐photon stereolithography setups and commercial 3D printers. The fabricated objects were shown to degrade in basic solvent as well in a homemade compost. The rate of degradation is nonetheless dependent on the size of the object. This feature was used to prepare 3D objects with support structures that could be easily solubilized.

3D printing and especially VAT photopolymerization leads to cross-linked materials with high thermal, chemical and mechanical properties. Nevertheless, such stability is incompatible with degradability and re/upcyclability. We showed here that thionolactone and especially dibenzo[c,e]-oxepane-5-thione (DOT) could be used as an additive (2 wt%) to acrylate-based resins to introduce weak bonds into the network via a radical ring-opening polymerization process. The low amount of additive allows to only slightly modify the printability of the resin, keep intact its resolution and maintain the mechanical properties of the 3D object. The resin with additive was used in UV microfabrication and 2-photon stereolithography setup and commercial 3D printers. The fabricated objects were shown to degrade in basic solvent as well in a home-made compost. The rate of degradation is nonetheless dependent of the size of the object. This feature was used to prepare 3D objects with support structures that could be easily solubilized.

Vat photopolymerization relies on the light‐induced polymerization of liquid photopolymer to produce the targeted structure. Among all the polymers prepared by vat photopolymerization, due to their numerous properties polyurethanes have recently gained great attention in the industrial and academic fields. In this review article, recent progress in printing techniques, resin compositions, and applications related to 3D/4D printing by vat photopolymerization of polyurethanes are highlighted.

Three‐dimensional (3D) printing and especially VAT photopolymerization leads to cross‐linked materials with high thermal, chemical, and mechanical stability. Nevertheless, these properties are incompatible with requirements of degradability and re/upcyclability. We show here that thionolactone and in particular dibenzo[c,e]‐oxepane‐5‐thione (DOT) can be used as an additive (2 wt %) to acrylate‐based resins to introduce weak bonds into the network via a radical ring‐opening polymerization process. The low amount of additive makes it possible to modify the printability of the resin only slightly, keep its resolution intact, and maintain the mechanical properties of the 3D object. The resin with additive was used in UV microfabrication and two‐photon stereolithography setups and commercial 3D printers. The fabricated objects were shown to degrade in basic solvent as well in a homemade compost. The rate of degradation is nonetheless dependent on the size of the object. This feature was used to prepare 3D objects with support structures that could be easily solubilized.