NMR characterization of sodium carboxymethyl cellulose: Substituent distribution and mole fraction of monomers in the polymer chains

Hiroyuki Kono; Kazuhiro Oshima; Hisaho Hashimoto; Yuuichi Shimizu; Kenji Tajima

doi:10.1016/j.carbpol.2016.03.021

NMR characterization of sodium carboxymethyl cellulose: Substituent distribution and mole fraction of monomers in the polymer chains

Carbohydr Polym. 2016 Aug 1:146:1-9. doi: 10.1016/j.carbpol.2016.03.021. Epub 2016 Mar 14.

Authors

Hiroyuki Kono¹, Kazuhiro Oshima², Hisaho Hashimoto², Yuuichi Shimizu², Kenji Tajima³

Affiliations

¹ Department of Science and Engineering for Materials, Tomakomai National College of Technology, Nishikioka 443, Tomakomai, Hokkaido 059 1275, Japan. Electronic address: kono@sem.tomakomai-ct.ac.jp.
² Department of Science and Engineering for Materials, Tomakomai National College of Technology, Nishikioka 443, Tomakomai, Hokkaido 059 1275, Japan.
³ Faculty of Engineering, Hokkaido University, N13W8, Kita-ku, Sapporo 060 8628, Japan.

PMID: 27112844
DOI: 10.1016/j.carbpol.2016.03.021

Abstract

A series of sodium carboxymethyl cellulose (CMC) samples with degrees of substitution (DS) from 0.68 to 2.84 were prepared from cellulose by multistep carboxymethylation. Two-dimensional NMR spectroscopic analyses allowed complete assignment of the (1)H and (13)C chemical shifts of the eight anhydroglucose units (AGUs) found in CMC: 2,3,6-tri-, 2,3-di-, 2,6-di-, 3,6-di-, 2-mono-, 3-mono-, 6-mono-, and unsubstituted AGUs. A comparative analysis of the chemical shift data revealed the substituent effects of the carboxymethyl groups at the 2-, 3-, and 6-positions on the (1)H and (13)C chemical shifts of the AGUs and that additivity could be applied to the (1)H and (13)C chemical shifts of CMC. Quantitative (13)C NMR spectra of the CMC samples allowed determination of the AGU composition, as well as the substituent distribution at the 2-, 3-, and 6-positions of cellulose, which allowed estimation of the reactivity of the hydroxyl groups toward the carboxymethylation.

Keywords: Carboxymethyl cellulose; Chemical shift additivity; Monomer composition; Substituent distribution; Substituent effect.

Publication types

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

MeSH terms

Carboxymethylcellulose Sodium / chemistry*
Magnetic Resonance Spectroscopy*
Polymers / chemistry*

Substances

Polymers
Carboxymethylcellulose Sodium