Over the past decades, there has been extensive research in esterification of native cellulose and recently, it has been extended to nanocelluloses, particularly, cellulose nanocrystals (CNCs).  The design of simple esterification techniques will lead to a wide range of structural and functional moieties covalently grafted on the surface of nanocelluloses for various applications. Previous typical methods involved typical Fisher esterification reaction between the hydroxyl groups of nanocellulose and carboxylic acids in the presence of acid as catalyst. In this work, we have reversed the chemical method by starting with carboxylated CNCs and studied their esterification reactions with simple alcohols and a fluorescent alcohol under a organic solvent-free condition.  The green esterification reaction was performed in water at room temperature for 24 h in the presence of bismuth trichloride as an inexpensive, mild, easily handled, and green Lewis acid catalyst. The resulting surface esterified CNCs products were purified by centrifugation, dialysis and isolated by freeze-drying.  Proof of covalent ester linkages was obtained by FT-IR spectroscopy, and their hydrodynamic size and surface charge were analyzed by DLS and zeta potential measurements respectively. Fluorescent CNCs were analyzed by UV-VIS and fluorescence spectroscopy and could potentially be useful for bioimaging application.<br/>

Green surface esterification method of carboxylated cellulose nanocrystals

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.