Mechanical Properties Tailoring of 3D Printed Photoresponsive Nanocellulose Composites

3D printing technologies allow control over the alignment of building blocks in synthetic materials, but compositional changes often require complex multimaterial printing steps. Here, 3D printable materials showing locally tunable mechanical properties are produced in a single printing step of Direct Ink Writing. These new inks consist of a polymer matrix bearing biocompatible photoreactive cinnamate derivatives and up to 30 wt% of anisotropic cellulose nanocrystals. The printed materials are mechanically versatile and can undergo further crosslinking upon illumination. When illuminating the material and controlling the irradiation doses, the Young's moduli can be adjusted between 15 and 75 MPa. Moreover, spatially controlled illumination allows patterning stiff geometries, resulting in 3D printed structures with segments of different mechanical properties tailoring the mechanical behavior under compression. The high design freedom implemented by 3D printing and photopatternability opens the venue to rapid manufacturing of devices for applications such as prosthetics or soft robotics where the 3D shapes and mechanical properties must be tailored for personalized load cases.