Facile surface modification of amphiphilic cellulose nanofibrils prepared by aqueous counter collision.

The present study concerns the chemical modification of the surfaces of cellulose nanofibrils (CNFs) prepared by aqueous counter collision (ACC). Wood-derived CNFs prepared by ACC were acetylated with acetic anhydride in an aqueous dispersion. The moderately acetylated nanofibrils were more readily dispersible in water than unmodified CNFs, although the original nanofibrous morphology comprising crystalline cellulose I remained almost unchanged. This indicates that the surfaces of the crystalline CNFs had been selectively acetylated, which possibly inhibited self-aggregation between the nanofibrils, thereby facilitating dispersion in the aqueous medium. Despite the absence of additives, the acetylated CNFs were readily adsorbed onto hydrophobic surfaces, and retained their compatibility with water, which improved their ability to stabilize emulsions and coat plastic resin particles in water. The results indicate that the amphiphilic properties of CNFs prepared by ACC can be controlled by this facile surface acetylation method, which potentially increases their usefulness in various fields.