ABSTRACT
The research on cellulose nanocrystals (CNCs) focuses largely on what can be categorised as materials science and/or technology. The chapter focuses on the fundamental structure of native cellulose that allows the preparation of CNCs. Other than sulphuric acid, hydrolysis with other strong mineral acids has received sparing attention. Hydrochloric acid has been the most popular mineral acid, but its use has never gained widespread popularity because of the lack of charge on the resulting CNCs. Esterification as a promising route to CNC production first received attention in 2009 in a study by Braun and Dorgan who used acid-catalysed Fischer esterification of cellulose hydroxyls by acetic acid and butyric acid while simultaneously degrading the disordered portions of cellulose by HCl. With certain precautions, 2,2,6,6-tetramethylpiperidine-1-oxyl-mediated oxidation appears as an attractive choice for CNC preparation as well, particularly when using microcrystalline cellulose as a starting material.
