Effects of Incorporating Ionic Crosslinking on 3D Printing of Biomass–Fungi Composite Materials

Summary

Researchers developed an improved method for 3D printing with fungal composite materials made from agricultural waste and mushroom mycelium. By adding sodium alginate (a seaweed-derived thickener) and treating the printed objects with a calcium salt solution, they significantly improved the structural integrity and precision of the printed parts. This technique addresses a major challenge in the field where printed objects would shrink and warp after printing, making it possible to create complex shapes from sustainable, biodegradable materials.

Background

Biomass–fungi composite materials consist of agricultural residue particles bound by fungal hyphae networks and have potential applications in packaging, furniture, and construction. Traditional 3D printing of these materials faces challenges with geometric accuracy and height shrinkage during secondary colonization. Ionic crosslinking has been successfully used in hydrogel-based bioprinting but has not been previously applied to biomass–fungi composites.

Objective

This study investigates the effects of sodium alginate concentration and calcium chloride crosslinking exposure time on the quality and physiochemical properties of 3D printed biomass–fungi composite materials. The research aims to improve geometric accuracy and reduce height shrinkage by incorporating ionic crosslinking techniques.

Results

Samples from 2SA biomass–fungi mixture with 1-minute crosslinking demonstrated the best geometric accuracy and lowest height shrinkage compared to controls. Increasing sodium alginate concentration improved viscosity and reduced height shrinkage significantly. FTIR spectroscopy confirmed ionic crosslinking through shifts in carbonyl stretching bands, and texture analysis showed crosslinking substantially increased hardness while sodium alginate improved cohesiveness and springiness.

Conclusion

Ionic crosslinking effectively enhances the quality of 3D printed biomass–fungi composite materials by improving geometric accuracy and reducing height shrinkage. The optimal formulation was 2% sodium alginate with 1-minute crosslinking exposure, which maintained superior dimensional stability through the secondary colonization process without causing material brittleness or deformation.
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