All-cellulose resin for 3D printing hydrogels via digital light processing (DLP)

3D printing has emerged as a transformative technology in sustainable manufacturing, enabling rapid prototyping, minimizing material waste, and reducing the carbon footprint associated with traditional methods. However, their reliance on fossil-based materials limits their broad application. This study presents a novel approach for developing a single-component, fully cellulosic, natural-based resin for 3D printing hydrogels using digital light processing (DLP). Cellulose was dissolved in an aqueous alkali/urea system and modified to obtain photopolymerizable derivatives. Two cellulose sources were used: Avicel® and cellulose pulp obtained from an industrial process. The single-polymer resins produced dimensionally stable, free-standing 3D objects with good resolution and shape fidelity. Despite the low polymer concentration (2.5 and 5 wt%), the cellulose resins exhibited fast curing kinetics, producing hydrogels with good mechanical properties, capable of withstanding compressive stress up to 135 kPa. Additionally, the printed hydrogels absorbed and retained large amounts of water (up to 427 %), while maintaining their shape and integrity in acidic and alkaline media. The hydrogels were stable to hydrolytic degradation, maintained their shape for up to four weeks, and were cytocompatible with fibroblast cells, indicating their potential for biomedical applications.