Preparing flake nanocelluloses with hydrophobic surface from the spent liquor of cellulose nanocrystals

It is of great value to reuse of the dissolved carbohydrates from the spent liquor produced in the acid hydrolysis process of cellulose nanocrystals (CNCs). In the present study, a special flake-like nanocellulose crystals (FCNCs) were self-assembled from the dissolved cellulose chains with low molecular weight via a "bottom-up" approach. The average diameters of FCNCs were 712 nm, with thickness in the range of 3 ~ 3.5 nm. They exhibited superior thermal stability relative to CNCs. XRD characterization revealed that the FCNCs with the cellulose type II structure possessed the hydrophobic (110) plane as the exposed surface which endowed the material with relatively hydrophobic property. Confirmed by the contact angle tests, the water contact angle value of FCNCs film was as high as 72.0°, almost twofold of that of CNCs film.