Hirotaka Koga

Water containing low amounts of cellulose nanofiber (CNF) is widely used as a thickening agent owing to its three unique properties: high transparency, viscosity, and controllable viscosity based on the shear rate. CNF dry powders are used to reduce the transportation and storage costs or expand applications as a thickening agent. Herein, the preparation of CNF dry powders that can be used to obtain redispersions while maintaining the aforementioned properties is reported. In this regard, the dehydration and vaporization procedures for a CNF water dispersion without using additives are discussed. When dry powders are prepared by removing water by boiling, their redispersions do not exhibit all their unique properties because of dense aggregations. However, when their redispersions are vigorously stirred to break the dense aggregations, they become transparent, although they do not recover their initial viscosity. Freeze‐dried powders recover all their initial properties after redispersion. Nevertheless, their large volume does not reduce the transportation and storage costs. When the liquid is evaporated from the solvent‐exchanged CNF organogels, their redispersions also fully recover all their properties. Furthermore, the evaporative dry powders with dense small volumes and good handling contribute to reducing the transportation and storage costs.