3. Cellulose nanocrystals

The preparation of cellulose nanocrystals (CNCs) involves a chemical hydrolysis process designed to dissolve the amorphous chains of cellulose fibers, thereby releasing the crystalline domains. The latter thus consist of a sub-entity of the cellulose microfibrils with better-defined geometric characteristics and higher crystallinity than the CNFs. Acid hydrolysis is the classic method for preparing CNCs. However, other processes, enabling the release of crystalline domains from cellulose fibers, have recently been reported in the literature. Most studies refer to cellulose nanocrystals, although polysaccharide nanocrystals can also be obtained from chitin or starch.