(431f) Impacts of Surface Functionalization on the Cellulose Nanocrystal Solubility in Ethanol

Cellulose-based materials have emerged as viable candidates for many industrial and academic studies due to their abundance, nontoxicity, and renewability. Recent progress in forming stable oil-in-water nanoemulsions using functionalized Cellulose Nanocrystals (CNC) yielded growing interest in adopting CNCs as emulsifiers. Nevertheless, the insolubility of CNCs in non-water solvents impeded them from stable nonaqueous emulsification, e.g., 2D material inks in ethanol.

Functionalization of CNCs’ surfaces alters the hydrophilicity/hydrophobicity balance and potentially enhances their solubility in ethanol. Understanding the underlying physics of the agglomeration of CNCs will assist us in recognizing the influence of chemical modifications on CNCs’ solubility in ethanol. We performed Molecular Dynamics simulations to evaluate the effects of surface modifications using several functional groups, e.g., alkyl, carboxyl, etc., on the behavior of Cellulose-ethanol systems. We used the extended version of the OPLS-AA force field for carbohydrates to model bond, angle, dihedral, and Van der Waals interactions.

We adopted the Alchemical free energy and Umbrella Sampling methods and investigated the impact of surface functionalization on Cellulose chain solubility and CNCs’ dispersibility in ethanol. Further, we analyzed the variation of the tendency of CNCs to reaggregate as the function of the degree of substitution of the functional groups. Finally, we will explore the capability of the CNCs with improved solubility to exfoliate 2D materials, e.g., graphene, in ethanol.