A dispersion of cellulose nanowhiskers (CNWs) was prepared by hydrochloric acid hydrolysis of native cotton, washing with water, and subsequent homogenization in organic solvents. Ultrafine dry powders of CNWs were obtained without hornification (i.e., formation of rigid films) by homogenization of the cellulose hydrolysate in solvents with a small dielectric constant, e.g., toluene or cyclohexane, and subsequent air-drying. Despite using no surface modifications or additives, the obtained pure CNW powders indicated outstanding redispersibility in water compared with conventional CNWs dried from water or large-dielectric constant solvents. Homogenization in organic solvents with smaller dielectric constants (toluene and cyclohexane) yielded finer powders with higher redispersion in water than those obtained using larger dielectric constants (dimethylacetamide, acetonitrile, and water). The extent of hornification also depended upon the dielectric constant of the solvent; i.e., using a solvent with a larger dielectric constant resulted in severer hornification.
- Cellulose nanowhiskers
- Nonpolar organic solvent