Title
Solid-state 23Na NMR spectroscopy studies of ordered and disordered cellulose nanocrystal films
Author
Ryutaro Ohashi, Carl A. Michal, Wadood Y. Hamad, Thanh-Dinh Nguyen, Motohiro Mizuno, Mark J. MacLachlan
Year
2019
Journal
Solid State Nuclear Magnetic Resonance
Abstract
Cellulose nanocrystal films with either disordered or chiral nematic structures of varying helical pitch were investigated using 23Na solid-state nuclear magnetic resonance (NMR) spectroscopy. Spin lattice relaxation of 1H correlated with 23Na analyzed by indirect observation using polarization transfer from 1H nuclei to 23Na nuclei showed that the Na+ cations are well hydrated in the cellulose nanocrystal films. Linewidth analysis in solid-state 23Na NMR showed that the Na+ cations move in confined spaces, and that the Na+ cations in the film having disordered structure are more dynamic than in the films having ordered structure. From lineshape analysis of the 23Na 2D nutation NMR spectra, we can distinguish the Na+ environments within the ordered and disordered films, and find trends in anisotropic interaction parameters between ordered samples with different pitches. These are the first detailed 23Na NMR spectroscopic studies of CNC-Na+ films, and they show that this technique may be a powerful probe for characterizing the extent of order in nanocellulose samples.
Instrument
J-815
Keywords
Circular dichroism, Solid state, Materials