3D printing of fully cellulose-based hydrogels by digital light processing

We report on the development of natural-based, composite hydrogel inks for Digital Light Processing (DLP) 3D printing, composed entirely of cellulose-based-materials. DLP, which enables the production of complex constructs by photopolymerization, is already considered an environmentally friendly production method but it is still based on fossil chemicals, which may be a limit in the future. On the contrary, in view of a more environmental-friendly production, the development of natural inks will represent a further step to its wide-scale adoption. Here acrylated-carboxymethyl cellulose (mCMC) hydrogels are reinforced by the addition of biowastes-sourced cellulose nanocrystals (NCs) derived from oil palm empty fruit bunch, both pristine and functionalized, to produce hybrid polymeric networks. It is demonstrated that the addition of such fillers does not affect the photocuring properties of the formulations while improving their printability through improvement in the mechanical properties, even with high content of water (97 wt%). Furthermore, the printable hydrogels present intriguing characteristics such as controlled swelling and pH sensitivity. The use of fully-natural derived material with designed properties and complex geometries can open further perspectives in many fields, such as sensors, biomedical and soft robotics.