EPR spectroscopy applied to the study of the TEMPO mediated oxidation of nanocellulose

Juan M Buffa; María Alejandra Grela; Mirta I Aranguren; Verónica Mucci

doi:10.1016/j.carbpol.2015.09.094

EPR spectroscopy applied to the study of the TEMPO mediated oxidation of nanocellulose

Carbohydr Polym. 2016 Jan 20:136:744-9. doi: 10.1016/j.carbpol.2015.09.094. Epub 2015 Sep 30.

Authors

Juan M Buffa¹, María Alejandra Grela², Mirta I Aranguren¹, Verónica Mucci³

Affiliations

¹ Institute of Research in Materials Science and Technology (INTEMA), National University of Mar del Plata-CONICET, Argentina.
² Department of Chemistry, National University of Mar del Plata-CONICET, Argentina.
³ Institute of Research in Materials Science and Technology (INTEMA), National University of Mar del Plata-CONICET, Argentina; Department of Chemistry, National University of Mar del Plata-CONICET, Argentina. Electronic address: vmucci@fi.mdp.edu.ar.

PMID: 26572408
DOI: 10.1016/j.carbpol.2015.09.094

Abstract

Two different methods of pH control were used in the synthesis of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanocrystals (CNC) and the reaction kinetics and degree of oxidation were investigated. In method I the media pH was controlled by addition of NaOH solution. The effect of the oxidant concentration (sodium hypochloride, NaClO) on the final degree of oxidation and crystallinity of the samples was investigated. Conditions for obtaining an optimum balance between high crystallinity and degree of oxidation were selected from those results. In method II, pH was fixed by using a buffer solution. Electron spin resonance (ESR) spectroscopy offered direct information of the decay of TEMPO concentration under these conditions. The kinetics of the reaction was determined, finding a direct correlation between these results and those corresponding to the decay of the NaClO concentration and the advance of the CNC degree of oxidation. Differences found between the two methods were analyzed.

Keywords: Cellulose nanocrystals; Conductimetry; EPR; ESR; TEMPO.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cellulose / analogs & derivatives*
Cellulose / chemistry
Dextrans / chemistry*
Electron Spin Resonance Spectroscopy
Nanoparticles / chemistry*
Oxidation-Reduction

Substances

2,2,6,6-tetramethylpiperidine-1-oxyldextran
Dextrans
Cellulose