Bio-based nanocomposites obtained through covalent linkage between chitosan and cellulose nanocrystals

Bio-based nanocomposites were obtained through covalent linkage between cellulose nanocrystals (CNCs) and the natural polymer chitosan (CH). The CNCs were first functionalized with methyl adipoyl chloride (MAC) and the reactive end groups on the surface of the CNCs were reacted with the amino groups of the CH biopolymer in an aqueous medium. The functionalized CNCs and the resulting nanocomposites were characterized using FTIR, TEM, XRD, and elemental analyses. Characterization of the functionalized CNCs showed that up to 8% of the hydroxyl groups in the nanocrystals were substituted by the MAC residue. The covalent linkage between the CNCs and CH was confirmed by FTIR spectroscopy. The nanocomposites demonstrated a significant improvement in the mechanical performance and a considerable decrease in the hydrophilicity relative to the neat chitosan. The approach used in this work can be extended to other natural polymers.