cellulose nanocrystals (cnc), rigid rod-like nanoparticles, are derived from cellulose through acid hydrolysis and are considered as emerging nanomaterials according to their beneficial properties and commercial availability. in this thesis, the use of cnc derivatives in novel applications was explored. to make cnc more suitable for these applications, carboxyalkylation has been carried out to increase the charge density of cnc and induce hairy structure on the surface of cnc. since the dispersibility of kaolinite particles are very crucial in their end-use applications ranging from cosmetics to drilling, carboxymethylated cnc was used as a dispersant to increase the stability of such suspensions. in the meantime, cnc was produced in different sizes prior to carboxymethylation to analyze the effect of cnc size on its performance as a dispersant. it was observed that the larger the modified cnc, the higher the charge density, and thus, the more the cnc adsorption to kaolinite particles. hence, with increasing the cnc size, a lower dosage of modified cnc was observed to be required for attaining better kaolinite stability, which would be industrially attractive. another fundamental discovery of this research study was that the functional groups on the carboxymethylation of cnc was observed to play a more critical role in the settling affinity of the kaolinite particles than the cnc size.