title: Homogeneous suspensions of individualized microfibrils from TEMPO-catalyzed oxidation of native cellulose.
abstract: Never-dried native celluloses (bleached sulfite wood pulp, cotton, tunicin, and bacterial cellulose) were disintegrated into individual microfibrils after oxidation mediated by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical followed by a homogenizing mechanical treatment. When oxidized with 3.6 mmol of NaClO per gram of cellulose, almost the totality of sulfite wood pulp and cotton were readily disintegrated into long individual microfibrils by a treatment with a Waring Blendor, yielding transparent and highly viscous suspensions. When observed by transmission electron microscopy, the wood pulp and cotton microfibrils exhibited a regular width of 3-5 nm. Tunicin and bacterial cellulose could be disintegrated by sonication. A bulk degree of oxidation of about 0.2 per one anhydroglucose unit of cellulose was necessary for a smooth disintegration of sulfite wood pulp, whereas only small amounts of independent microfibrils were obtained at lower oxidation levels. This limiting degree of oxidation decreased in the following order: sulfite wood pulp > cotton > bacterial cellulose, tunicin.
authors.affiliation: Centre de Recherches sur les Macromolécules Végétales, CNRS/ICMG/UJF, BP 53, F-38041 Grenoble Cedex 9, France.
authors.forename: Tsuguyuki
authors.initials: T
authors.lastname: Saito
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Nishiyama
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Putaux
authors.forename: Michel
authors.initials: M
authors.lastname: Vignon
authors.forename: Akira
authors.initials: A
authors.lastname: Isogai
mesh_terms: D002384:Catalysis; D002482:Cellulose / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry*; D020894:Microfibrils / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D013535:Suspensions
chemical_list: D003497:Cyclic N-Oxides; D013535:Suspensions; D002482:Cellulose; C003959:TEMPO