Additive Manufacturing of Neem Oil‐Derived Resin via Digital Light Processing for Biomedical Applications

The growing demand for sustainable materials in additive manufacturing (AM) has prompted the investigation of bio‐based substitutes for petroleum‐derived resins. Among AM processes, digital light processing (DLP) offers high precision but relies on nonbiodegradable photopolymers. This study introduces a UV‐curable acrylate resin formulated from Azadirachta indica (neem) oil, a renewable, antimicrobial material, for DLP 3D printing. Neem oil underwent epoxidation via a methyltrioxorhenium (MTO)‐catalyzed biphasic system at ambient temperature, followed by acrylation to produce a DLP‐compatible bio resin. The resin demonstrated favorable photocuring behavior and facilitated high‐resolution, defect‐free printing. Comprehensive characterization demonstrated excellent mechanical strength, flexibility, and rheological stability. Biological assessments validated superior cytocompatibility, hemocompatibility, and controlled hydrolytic breakdown. This is, to our knowledge, the first study on MTO‐based epoxidation and acrylation of neem oil for DLP 3D printing. The acrylate showed 75% conversion of double bonds and a printable viscosity of 3.6 Pa.s. The printed polymer demonstrates elastic behavior with an ultimate compressive strength of 246.3 ± 42.2 kPa at 52.0% ± 3.9% strain. The material showed excellent cytocompatibility, with more than 95% of NIH‐3T3 cell viability at 24 and 72 h, making it a viable solution for biomedical applications, including implanted devices, wound healing, and anti‐infection coatings.