(590b) Nanoengineering of Cellulose Nanocrystals for Enhanced Aqueous Redispersibility

Maintaining redispersibility of colloidal particles to yield a uniform dispersion post drying is a persistent challenge for nanocellulosic materials. Drying-induced irreversible aggregation may compromise the functionality, and consequently, the properties and applications of nanocelluloses. Conventional cellulose nanocrystals (CNC) have poor redispersibility as a result of irreversible hydrogen bonding, which renders their storage and transportation difficult. In this work, we engineer the redispersibility of CNC by tailoring the colloidal repulsive forces. Electrostatic and steric repulsion was imparted to CNC via two layers of disordered cellulose chains on each end (hairs) bearing a high density of dicarboxylate groups (up to ~5 mmol g^-1). Such anionic hairy cellulose nanocrystals (AHCNC), synthesized by the preferential oxidation of the disordered regions of cellulose fibrils, attain extraordinary redispersibility compared to conventional CNC, even at high initial concentrations, high ionic strengths, and extreme pH conditions. The unique redispersibility mechanism of AHCNC may open new opportunities for more sustainable and cost-effective processing of nanocelluloses.