3D printing is revolutionizing the manufacturing field where melted plastics and metals are used to print prototypes and spare parts. However, renewable biopolymers which do not melt, such as cellulose, are not yet taking part in the 3D printing revolution. Here, we use a 3D bioprinter to 3D print a hydrogel consisting of 2 % surface charged cellulose nanofibrils (CNF) and 98 % water. The shear thinning property of the material and recovery is proven to be necessary for the 3D printing of gels, and the hydrogel presented here has both these properties. Since most applications rely on dry materials, the water is removed after printing by four different schemes, resulting in dry structures with different appearance and properties. Drying in air results in significant shrinkage, while the structure can be kept intact by freeze drying. An image of a wet grid cube is shown in the figure, along with examples of dry cubes from the four different solidification processes. Dry structures have for the first time been produced by 3D printing and solidification of pure cellulose. Development of printable materials that are both recyclable and renewable is crucial if the 3D printing technology itself should be seen as sustainable, and by showing that it is possible the 3D print CNF, a step in that direction has been made.

Solidification of 3D printed cellulose nanofibrils

251st National Meeting (2016)

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