Preparation of thermally stable and surface-functionalized cellulose nanocrystals by a fully recyclable organic acid and ionic liquid mediated technique under mild conditions

Here we report the preparation of thermally stable and surface-functionalized cellulose nanocrystals (CNCs) by a fully recyclable organic acid and ionic liquid (IL) mediated technique under mild conditions. The microcrystal cellulose (MCC) was firstly pretreated via a controlled partial swelling by IL to improve its accessibility. Subsequent hydrolysis of cellulose chains of MCC in amorphous regions by an organic acid (oxalic acid) under below 100 °C produced the surface-functionalized CNCs. The obtained CNCs exhibited excellent properties, such as a superb thermal stability ( T onset = 324 °C), a high crystallinity index (81.36%), a high surface charges loading (ζ =− 32 mV), and a uniform size distribution (average lengths of 202 nm). Therefore, the current study has a practical significance for the green and sustainable preparation of high-performance CNCs. Graphic abstract