Endowment of Excellent Water Redispersibility for Cellulose Nanocrystals Using the Strategy of Chemical Shielding and Dispersion with Debonding Agent

Abstract Cellulose Nanocrystals (CNCs), as an environmentally friendly, green and inexhaustible material, are widely used in transparent packaging, drug release, water purification etc. However, CNCs have an innate tendency to aggregate, and are difficult to be redispersed especially after drying. In this work, we propose a simple and easy-to-use route to render the CNCs with excellent redispersibility by adding a debonding agent (DA). The redispersed CNCs are named Re/mDA-CNCs. Here m represents the percentage amount of DA and Re is an abbreviation for redispersed. The results show that the Z-average size of Re/0.4DA-CNCs after redispersion is consistent with that of original CNCs, and the size distribution is uniform. The Zeta potential of Re/0.4DA-CNCs is lower than that of the original CNCs. The reason is that the electrostatic repulsion between the hydrophobic groups in DA and the -OH groups on the CNC surface leads to the neutralization of the cationic groups in DA with the -OH groups on the CNC surface, which reduces the amount of H-bonding formed through -OH groups in CNC intramolecular. Furthermore, the FT-IR and XRD results indicate that the successful introduction of DA to the CNC surface shield the formation of H-bonding by -OH groups in CNC intramolecular, leading to the decrease of CNC cornification without changing the basic chemical structure of the CNCs. The Re/0.4DA-CNCs demonstrate potential applications in the field of food packaging, biological medicine, etc.