High-Yield Synthesis of Functionalized Cellulose Nanocrystals for Nano-Biocomposites

A facile versatile green one-step procedure to fabricating functionalized cellulose nanocrystals (CNCs) with high yields and thermostability was put forward via molten oxalic acid hydrolysis by aid of simultaneous microwave and sonication. The synchronized hydrolysis and esterification of cellulose took place in the one-pot solvent-free reaction, and thus we developed an environmentally benign and scalable concurrent acid hydrolysis/Fischer esterification method to produce acid-functionalized CNCs using microwave and sonication in 85.5% yield. Compared to classical methods for the functionalization of CNCs, the presented study avoided the extensive consumption of water and solvent and achieved zero waste liquid discharge. Moreover, the used solid acid could easily be recycled to make it possible for the large-scale and cleaner production of CNCs. The resultant CNCs with high thermal stability and excellent dispersion stability are excellent for nano-biocomposite applications.