Steric stabilization of cellulose nanocrystals by dextran grafting

This is the authors' abstract. We don't add key points for this paper.

In this study, an enhanced dispersion stability of cellulose nanocrystals was achieved by terminal grafting of dextran (alpha-1,6 glucan) onto their surface. The carbon at the 6-position of the nanocrystal was first oxidized by the TEMPO method; then, the introduced carboxyl group on the surface of the cellulose nanocrystal was coupled with the terminal amino group of terminally aminated dextran using N -hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. Terminally aminated dextran was obtained by reductive amination using sodium cyanoborohydride and ammonium chloride. The weight gain induced by grafting reached 184% of the carboxylated cellulose nanocrystal, resulting in a high dispersion stability. The dispersion stability was evaluated by calculating the change in viscosity before and after adding salt. Typically, cellulose nanocrystals are charged colloids; hence, adding salt reduces their dispersion stability and increases their viscosity. However, the addition of 0.05 M CaCl 2 to a suspension of dextran-grafted cellulose nanocrystals did not cause a noticeable increase in viscosity or turbidity. This enhanced stability highlights the effectiveness of coating cellulose nanocrystals with water-soluble polymers.