High-performance, high biobased content, self-repairable, and recyclable biobased photopolymers for UV-curing 3D printing

Incorporation of renewable resources, green synthesis methods, self-repairability, and recyclability into the fabrication of UV-curing 3D printing materials can greatly improve the sustainability of such advanced materials. In this work, we report the development of castor oil (CO)-based polyurethane acylate resins containing dynamic disulfide bonds (COPUA-SS) for UV-curing 3D printing via a 'one-pot no-solvent' method involving the empolyment of a biobased diluent, tetrahydrofurfuryl methacrylate, as sovlent. By varying the feed ratios, a set of UVcuring 3D printing materials with tunable thermal, mechnical, and dynamic properties as well as biobased contents were obtained. Notably, the optimal resin (COPUA-SS4) possessed excellent thermal and mechanical properties (a Tg of 94.6 degrees C and tensile strength of 70.4 MPa), high bio-based content (40.3 %), and relatively fast stress relaxation (15.8 min at 180 degrees C). By adding a UV blocker into the optimal resin, excellent UV-curing 3D printing performance were achieved. Furthermore, the 3D printed objects based on the optimal resin demonstrated superior self-repairability, recyclability, and plasticity as well as good shape memory properties. For instance, the materials demonstrated a healing efficiency of 100 % under heating at 160 degrees C for 30 min and a recycling efficiency of tensile modulus up to 168.4 % after the first recycling. This study paves the way to develop UV-curing materials with high performance and more sustainability, which show great promise to be applied in 3D printing structural areas like artefacts.