Room-Temperature, Aqueous-Based 3D Printing of Fully Recyclable Wood-like Inks from Upcycled Lignin

High Resolution Image Download MS PowerPoint Slide Despite growing interest in sustainable additive manufacturing, most 3D printing inks rely on fossil-based polymers, require postprocessing, or lack recyclability. Here, we report a fully recyclable, water-based ink composed of 70 wt % lignosulfonate, an abundant industrial byproduct, formulated for high-resolution 3D printing via direct ink writing at room temperature. This ink eliminates the need for chemical cross-linkers, organic solvents, or energy-intensive postcuring. Its tailored rheology, governed by reversible hydrogen bonding and hydrophobic interactions, ensures excellent shape fidelity and print stability. Mechanical properties are tunable via glycerol content, and shape stability of up to 200 °C can be achieved. The material is fully recyclable by simple rehydration without a loss in performance. This sustainable and scalable formulation bridges biomass valorization, functional prototyping, and circular manufacturing on a unified platform.