Isogai, Akira and Saito, Tsuguyuki and Fukuzumi, Hayaka (2010) TEMPO-oxidized cellulose nanoﬁbers. Nanoscale .
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Native wood celluloses can be converted to individual nanoﬁbers 3–4 nm wide that are at least several microns in length, i.e. with aspect ratios >100, by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation and successive mild disintegration in water. Preparation methods and fundamental characteristics of TEMPO-oxidized cellulose nanoﬁbers (TOCN) are reviewed in this paper. Signiﬁcant amounts of C6 carboxylate groups are selectively formed on each cellulose microﬁbril surface by TEMPO-mediated oxidation without any changes to the original crystallinity ( 74%) or crystal width of wood celluloses. Electrostatic repulsion and/or osmotic effects working between anionically-charged cellulose microﬁbrils, the z-potentials of which are approximately 75 mV in water, cause the formation of completely individualized TOCN dispersed in water by gentle mechanical disintegration treatment of TEMPO-oxidized wood cellulose ﬁbers. Self-standing TOCN ﬁlms are transparent and ﬂexible, with high tensile strengths of 200–300MPa and elastic moduli of 6–7 GPa. Moreover, TOCN-coated poly(lactic acid) ﬁlms have extremely low oxygen permeability. The new cellulose-based nanoﬁbers formed by size reduction process of native cellulose ﬁbers by TEMPO- mediated oxidation have potential application as environmentally friendly and new bio-basednanomaterials in high-tech ﬁelds.
|Subjects:||Material Science > Nanochemistry|
|Deposited On:||28 Nov 2010 15:16|
|Last Modified:||28 Nov 2010 15:16|
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