Review: Catalytic oxidation of cellulose with nitroxyl radicals under aqueous conditions. (November 2018)

• Record Type: Journal Article
• Authors: Isogai, Akira; Hänninen, Tuomas; Fujisawa, Shuji; Saito, Tsuguyuki
• Is Part Of: Progress in polymer science. Volume 86(2018)
• Page Start: 122
• Page End: 148
• Publication Date: 2018-11
• Subjects: 4-AcNH-TEMPO 4-Acetamido-TEMPO -- AFM atomic force microscopy -- AZADO 2-azaadamantane N-oxyl radical -- CNC cellulose nanocrystal -- CTA cellulose triacetate -- DMAc N, N-dimethylacetamide -- DMF N, N-dimethylformamide -- DP degree of polymerization -- DS degree of substitution -- ESR electron spin resonance -- H-NBR hydrogenated butadiene-acrylonitrile rubber -- [η] intrinsic viscosity -- MALLS multi-angle laser-light scattering -- Mv viscosity-average molar mass -- NaTCC sodium 2, 3, 6-tricarboxylate cellulose -- NMR nuclear magnetic resonance -- PEG poly(ethylene glycol) -- PLA poly(lactic acid) -- RH relative humidity -- SEC size-exclusion chromatography -- TEM transmission electron microscopy -- TEMPO 2, 2, 6, 6-tetramethylpiperidine-1-oxyl radical -- TEMPO+ 2, 2, 6, 6-tetramethylpiperidine N-oxoammonium ion -- TOC TEMPO-oxidized cellulose -- TOCN TEMPO-oxidized cellulose nanofibril -- TO-CNC TEMPO-oxidized cellulose nanocrystal -- TOCN-PEG TOCN-COO−/+NH3-CH2CH2-(OCH2CH2)n-OCH3 -- UV ultraviolet; Cellulose -- TEMPO -- Nanofibril -- Catalytic oxidation -- N-oxyl radical -- Position-selective reaction -- Surface modification; Polymers -- Periodicals; Polymerization -- Periodicals; Polymers -- Industrial applications -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.progpolymsci.2018.07.007
• Languages: English
• ISSNs: 0079-6700

Abstract

Graphical abstract: 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.