**3. Deep eutectic solvent for cellulose nanocrystals preparation**

As described in the first part of this chapter, the traditional methods used to obtain cellulose nanocrystal consist of strong acid hydrolysis, enzymatic hydrolysis, or oxidation reactions. These treatments allow to hydrolyzing the amorphous regions in cellulose chains, and they are often followed by mechanical or ultrasonic treatment to homogenize the suspension. However, these methods use toxic chemicals and are difficult to industrialize.

