Vegetable oil-based non-isocyanate urethane methacrylate resins for greener vat photopolymerization 3D printing

The development of sustainable photopolymer resins is essential to mitigate the environmental impact of additive manufacturing technologies. Herein, we report, for the first time, the application of a high-performance non-isocyanate urethane methacrylate (NIUMA) monomer, derived from passion fruit seed oil and carbon dioxide, in vat photopolymerization 3D printing. The synthetic route to NIUMA provides a safer alternative to conventional isocyanate-based systems while enabling a bio-based carbon content of 72%. Photocurable formulations incorporating 2-hydroxyethyl methacrylate, also explored here for the first time in combination with NIUMA, exhibited high monomer conversion (>95%), tunable viscosities (21-930 mPa·s), low critical exposure energies (2.58-4.05 mJ cm-2), low volume shrinkage, and excellent printing resolution without the need for photoblockers. Sustainable formulation scores (SFS) reached up to 38, with NIUMA75 representing the first non-isocyanate urethane-based resin for vat photopolymerization to surpass an SFS of 30. The resulting 3D-printed materials display a unique combination of properties, including tunable thermomechanical behavior (Tg = 72-104 °C), shape memory, aggregation-induced luminescence, and alkaline degradability. Notably, this work provides the first evidence of dynamic polymer network (DPN) behavior in NIUMA-based materials, enabling reprocessability and self-healing. By integrating biomass valorization, CO2 utilization, circular material design, and advanced manufacturing, this study establishes a platform for sustainable, high-resolution photopolymer resins and expands the potential of NIUMA systems toward smart and functional 3D-printed materials