Recyclable and reprintable biobased photopolymers for digital light processing 3D printing

Developing recyclable biobased photopolymers for UV-curable 3D printing is of great significance for sustainable development of 3D printing industry. In this work, novel recyclable and reprintable castor oil (CO)-based photopolymers for digital light processing (DLP) 3D printing were developed via hindered urea bonds, a type of dissociating dynamic covalent bonds. Remarkably, the printed objects could be recycled in 4 h at 90 °C or 2 h at 100 °C without any catalysts or solvents, and the recycled resins had similar physiochemical properties, polymerization kinetics, and printing resolutions as the original resin. Furthermore, reprintable sacrificial molds and thermochromic materials were achieved with the optimal biobased resin, which can be used in complicated model casting and information encryption/anti-counterfeiting areas. In particular, thermochromic microcapsules could be recycled nondestructively from the printed thermochromic materials and reused in DLP 3D printing.