Naturally occurring α-hydroxy acids: Useful organocatalysts for the acetylation of cellulose nanofibres

Cellulose nanoribbons obtained from bacterial fermentation have been esterified by means of a solventless organocatalytic route. The esterification methodology involves acetic anhydride as acylant and three different α-hydroxy acids were tested as organocatalysts. By tuning the acetylation interval, bacterial nanocellulose (BNC) with varying degree of substitution could be obtained (i.e. DS=0.27-0.90). Esterified BNC has been characterized in terms of its morphology, chemical structure, crystallinity, wettability and dispersibility in different solvents. The results indicate the efficacy of the present methodology for the smooth acetylation of cellulose nanoribbons at moderate conditions, thereby expanding the role of organocatalysts in reducing the hydrophilicity of bacterial cellulose nanoribbons.