Room temperature preparation of cellulose nanocrystals with high yield via a new ZnCl2 solvent system

Here, a facile method to fabricate cellulose nanocrystals (CNCs) with high yield from microcrystalline cellulose (MCC) at room temperature (RT) is achieved by using a new solvent system of zinc chloride (ZnCl2) and a little amount of hydrochloric acid (HCl). Compared with sulphuric acid hydrolysis process, about one-fifth mole of acid is used for per gram of CNCs in our protocol. CNCs with rod-like morphology are regenerated with a maximum yield of 35.2% and high crystallinity of 73.8%. Moreover, with an additional 2 h of ball-milling, the yield of CNCs could significantly increase to 66.9% at RT. The possible formation mechanism for CNCs prepared by the solvent system of ZnCl2/HCl is proposed. As the first example of isolation of CNCs with high yield at RT using ZnCl2, this work provides a facile, energy-saving, and practical strategy for the preparation of cellulose nanomaterials.