Cellulose nanofibers prepared by TEMPO-mediated oxidation of native cellulose.
Never-dried and once-dried hardwood celluloses were oxidized by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated system, and highly crystalline and individualized cellulose nanofibers, dispersed in water, were prepared by mechanical treatment of the oxidized cellulose/water slurries. When carboxylate contents formed from the primary hydroxyl groups of the celluloses reached approximately 1.5 mmol/g, the oxidized cellulose/water slurries were mostly converted to transparent and highly viscous dispersions by mechanical treatment. Transmission electron microscopic observation showed that the dispersions consisted of individualized cellulose nanofibers 3-4 nm in width and a few microns in length. No intrinsic differences between never-dried and once-dried celluloses were found for preparing the dispersion, as long as carboxylate contents in the TEMPO-oxidized celluloses reached approximately 1.5 mmol/g. Changes in viscosity of the dispersions during the mechanical treatment corresponded with those in the dispersed states of the cellulose nanofibers in water.
Saito
Tsuguyuki
T
Department of Biomaterials Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
Kimura
Satoshi
S
Nishiyama
Yoshiharu
Y
Isogai
Akira
A
D002482:Cellulose / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry*; D010084:Oxidation-Reduction; D014867:Water / Q000737:chemistry
D003497:Cyclic N-Oxides; D014867:Water; D002482:Cellulose; C003959:TEMPO