Crystalline and Hairy Nanocelluloses for 3D Printed Hydrogels and Strongly Structured Cryogels

Abstract

This work addresses two main challenges in additive manufacturing of cellulosic hydrogels and cryogels. They are (1) the rheological properties of suspensions of electrosterically stabilized nanocrystalline cellulose (ENCC, a member of the family of hairy nanocelluloses) are inadequate for 3D printing of hydrogels and (2) 3D printed cellulose nanocrystal (CNC) cryogels have poor mechanical properties. The above limitations are effectively addressed by hybridization of CNC/ENCC in the presence of a salt at an optimized weight ratio. Controlling the CNC/ENCC weight ratio leads to high tunability of the rheological properties of the hybrid systems, resulting in high-fidelity printing of 3D hydrogels. Similarly, high tunability in the mechanical performance of the cryogels, obtained upon freeze drying of the printed hydrogels, is achieved by manipulating the CNC/ENCC ratio. Compared to neat CNC cryogels, the compressive strength of the CNC/ENCC (1:1) cryogels is 78% higher. Combined, CNC bestows high printability on the cryogels, while the presence of ENCC leads to the strengthening of the corresponding super porous solid materials. Our findings open new opportunities for sustainable, biocompatible, and lightweight cellulosic structured scaffolds that can be tailored for a broad spectrum of applications.