Improving dispersion stability of hydrochloric acid hydrolyzed cellulose nano-crystals.

Cellulose nano-crystals (CNC) have attracted great interests as a novel nanostructured material in recent years, thanks to their excellent mechanical properties, high surface area and lightweight and biocompatibility etc. Due to its low charged group content, CNC prepared from the hydrochloric acid hydrolysis has poor dispersibility in water, which hinders its further applications. In this work, well-dispersed cellulose nano-crystals are successfully prepared using a two-step method, consisting of hydrochloric acid hydrolysis, followed by adsorption of hexadecyl trimethyl ammonium bromide (CTAB) onto CNC. Results show that CTAB at a low concentration (0.13-0.47 mM) provides effective steric barriers to minimize the CNC aggregation, which is supported by TEM images and particle size distribution of CNC. At high CTAB concentrations (>0.5 mM), CNC aggregation occurs, which is due to the "bridging" effect of CTAB.