Ashori, A., Babaee, M., Jonoobi, M., & Hamzeh, Y.

Carbohydrate Polymers 102: 369–275.

2014

Cellulose nanofibers (CNFs), as bio-materials derived from wood or non-wood plants, have the advan-tages of being biodegradable, renewable, low cost, and having good mechanical properties compared tosynthetic nanofibers. CNFs have been used as reinforcement in polymeric matrices, however, due to theirpolar surface, their dispersibility in non-polar solvents and compatibility with hydrophobic matrices arepoor. In this work, the chemical modification of CNFs, using acetic anhydride in the presence of pyri-dine as a catalyst, was studied with the aim of changing the surface properties. Native and chemicallymodified CNFs were characterized in terms of dynamic absorption, thermal stability, surface chemistry,morphology, and crystal structure. The reaction of acetylation between the acetyl groups and the hydroxylgroups of the CNFs was examined using Fourier transform infrared (FT-IR) analysis, while its extent wasassessed by titration. The ester content of CNFs was higher for the acetylated samples compared to thecontrol samples. It was also shown that the crystallinity decreased moderately as a result of esterifica-tion. Thermal stability of the modified nanofibers was slightly increased. Unlike native CNFs, a stableaqueous suspension was obtained with the modified nanofibers in both ethanol and acetone. The contactangle measurements confirmed that the surface characteristics of acetylated CNFs were changed fromhydrophilic to more hydrophobic. In addition, the obtained acetylated CNFs showed more hydrophobicsurface, which is in favor of enhancing the hydrophobic non-polar mediums.