(197by) Development of a Modifiable Atomistic Cellulose Nanocrystal Model

The extremely low dispersibility of the carboxylic acid cellulose nanocrystals (CNC-COOH) in non-aqueous organic solvents prevented their massive utilization in many research or industrial areas. For example, despite the high affinity of the CNC-COOHs to stabilize graphene flakes, their low dispersibility in ethanol forbids their integration into graphene-based inks formulated in the ethanol solvent. To the best of our knowledge, the improvement of CNC-COOH’s dispersibility in organic solvents using covalent surface modification has not been investigated. Hence, in the current study, we carried out molecular dynamics simulation to investigate the impacts of the surface functionalization on CNC's dispersibility, and compared the results against our experimental measurements. Our potential of mean force (PMF) calculations revealed functionalization of CNC-COOHs with alkyl groups (CNC-COOH-alkyl), e.g., ethyl, butyl, hexyl, and octyl, enhances dispersibility in ethanol compared to the pristine CNC, either due to the reduced strength between the binding partners or a developed kinetic barrier along the binding pathway.

Our experimental dispersibility tests confirmed our simulation predictions, wherein the alkyl chain length increment increased the dispersibility. The well dispersion of CNC-COOH-alkyls in ethanol sets the stage for their integration as stabilizers in ethanol or other organic solvents.