A Direct Preparation of Cellulose Nanocrystals by ZnCl2-Based Deep Eutectic Solvent

Abstract

Here, we demonstrated a direct method to produce cellulose nanocrystals (CNCs) with a rod-like shape from microcrystalline cellulose by a ZnCl2-based deep eutectic solvent (DES) with a high yield (~80.1%). We obtained CNCs, crystalline index (68.9%), with a width of ~30–50 nm and a length of 200–400 nm. Importantly, we were able to functionalize the CNCs with an acetyl, -(CO)CH3, group, which could potentially modulate the hydrophobic property of the CNCs. We attributed the formation of the CNCs to the Lewis acid effect of ZnCl2, which can hydrolyze the amorphous cellulose regime. Our study opens a new path to directly isolate cellulose nanocrystals with several functional groups on the surface of CNCs.