Surface Functionality Influences pH- and Solvent-Dependent Colloidal Stability of Cellulose Nanocrystals

Abstract

Cellulose nanocrystals (CNCs) are promising sustainable nanomaterials for a wide range of applications. Yet, limitations remain in understanding their dispersion behavior in organic solvents and across pH conditions, especially after surface modification. In this work, CNCs were surface-functionalized with carboxy, amino, or vinyl groups and thoroughly characterized. Dispersion behavior was evaluated using dynamic light scattering, including measurements of hydrodynamic diameter and ζ-potential in water solutions at various pH levels and across different solvents. Colloidal stability strongly depends on surface functionality and solvent characteristics. A correlation with Kamlet-Abboud-Taft parameters was identified, linking dispersion behavior to solvent polarity and hydrogen-bonding ability, in relation to the pKa of the surface groups. These findings provide a semiquantitative framework for designing novel materials with CNC dispersions across diverse media.