Acetylation of Cellulose Nanowhiskers with Vinyl Acetate under Moderate Conditions

A novel and straightforward method for the surface acetylation of cellulose nanowhiskers by transesterification of vinyl acetate is proposed. The reaction of vinyl acetate with the hydroxyl groups of cellulose nanowhiskers obtained from cotton linters was examined with potassium carbonate as catalyst. Results indicate that during the first stage of the reaction, only the surface of the nanowhiskers was modified, while their dimensions and crystallinity remained unchanged. With increasing reaction time, diffusion mechanisms controlled the rate, leading to nanowhiskers with higher levels of acetylation, smaller dimensions, and lower crystallinity. In THF, a solvent of low polarity, the suspensions from modified nanowhiskers showed improved stability with increased acetylation.