Review: Catalytic oxidation of cellulose with nitroxyl radicals under aqueous conditions

Research output: Contribution to journalReview ArticleScientificpeer-review

Researchers

Research units

  • University of Tokyo

Abstract

2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation is a unique reaction to native and regenerated celluloses, and has advantages in terms of position-selective reaction at room temperature under aqueous conditions. When the TEMPO/NaBr/NaClO oxidation is applied to native celluloses in water at pH 10 under suitable conditions, the C6-primary hydroxy groups present on crystalline cellulose microfibril surfaces are mostly converted to sodium C6-carboxylate groups. Anionic sodium glucuronosyl units are densely, regularly, and position-selectively formed on crystalline cellulose microfibril surfaces, while maintaining the original cellulose morphology, cellulose I crystal structure, crystallinity, and crystal width. When TEMPO-oxidized celluloses (TOCs) prepared from, for example, wood cellulose have sodium C6-carboxylate contents >1 mmol/g, transparent highly viscous gels consisting of TEMPO-oxidized cellulose nanofibrils (TOCNs) with homogeneous widths of ≈3 nm and lengths >0.5 μm, dispersed at the individual nanofiber level, are obtained by gentle mechanical disintegration of TOCs in water. Alternative systems are as follows: TEMPO/NaClO/NaClO2 system, TEMPO electro-mediated oxidation, etc. TOCNs are promising new plant-based renewable nanofibers applicable to high-tech material fields.

Details

Original languageEnglish
Pages (from-to)122-148
Number of pages27
JournalProgress in Polymer Science
Volume86
Publication statusPublished - 1 Nov 2018
MoE publication typeA2 Review article in a scientific journal

    Research areas

  • Catalytic oxidation, Cellulose, N-oxyl radical, Nanofibril, Position-selective reaction, Surface modification, TEMPO

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