Preparation of Cellulose Single Microfibrils from Native Celluloses by TEMPO-Mediated Oxidation

摘要

When TEMPO-mediated oxidation is applied to native celluloses,significant amounts of carboxylate and aldehyde groups are formed at the C6 primary hydroxyl groups.The original fibrous forms of cellulose as well as the original cellulose I crystallinities are maintained even after TEMPO oxidation and the successive washing by filtration.However,the TEMPO-oxidized cellulose fibers can be converted to individualized cellulose single microfibrils about 4 nm in width and a few microns in length by gentle disintegration treatment,when the amount of carboxylate groups formed reaches a certain level.Thus,highly viscous and transparent cellulose single microfibrils/water dispersions can be obtained.Based on calculation,almost all C6 primary hydroxyl groups of the surface of each cellulose microfibril are needed to be oxidized to carboxylate groups by TEMPO-mediated oxidation for giving the transparent dispersions by disintegration treatment under mild conditions.