Rheological properties of cellulose nanofiber hydrogel for high-fidelity 3D printing.

Optimization of the rheological properties of the matrix is ​​critical for high-fidelity matrix-assisted 3D printing (MAP), which enables the free-form fabrication of fluidic soft materials. This report describes the generic criteria observable in the printing process of cellulose nanofiber (CNF) hydrogels: the sharpness of an angled line, the cross-sectional ratio of a feature, the surface roughness of features, and the completeness of multi-line writing. The concentration and physical properties of the CNF affects the printing fidelity by changing the values of the four criteria, which are closely related to the rheological properties of the matrix. The printing fidelity can be enhanced by the optimal combination of the inks and the CNF matrix. Hydrophilic and hydrophobic inks are printed in the CNF matrix demonstrating as a universal matrix for free-form fabrication with liquid inks.