Novel Tool for Characterization of Noncrystalline Regions in Cellulose:  A FTIR Deuteration Monitoring and Generalized Two-Dimensional Correlation Spectroscopy

Abstract

Our previous results indicated that noncrystalline regions in a regenerated cellulose film comprised at least three domains engaged in different manners of molecular assembly [Kondo et al. In Cellulose Derivatives; Heinze, T. J., Glasser, W. G., Eds.; ACS Symposium Series 688; American Chemical Society: Washington, DC, 1998; Chapter 12]. In this article, we attempt to characterize each of the three noncrystalline domains in the film. The method used was a FTIR monitoring of deuteration from hydroxyl (OH) groups to OD, leading to the two-dimensional (2D) correlation analysis. The time-scan spectra in the OH-OD exchanging reaction were transformed into two kinds of 2D correlation spectra, the synchronous and the asynchronous spectra. Of the two, some cross-peaks were found in the latter spectrum. This suggests that the asynchronous 2D correlation spectrum could differentiate the contribution of OH groups due to different frequencies of hydrogen bonds in each domain. Here we will show the validity of this 2D correlation method as a powerful tool to predict hydrogen-bonding networks of the noncrystalline domains in cellulose.

Polarized infrared microspectroscopy of single spruce fibers: Hydrogen bonding in wood polymers

“…22 By contrast, water molecules can be inserted in noncrystalline regions of cellulose and at accessible crystal surfaces and interfaces where the crystalline cellulose network is disrupted. 21,22,27 Thus, it is possible to distinguish the hydroxyl groups of inaccessible cellulose fibrils from those of accessible cellulose surface chains and amorphous cellulose 12 and presumably from hydroxyl groups of the less ordered or amorphous hemicelluloses-lignin matrix. 41 The average PM dichroic spectrum of three single fiber measurements in liquid D 2 O is shown in Figure 5.…”

“…30 This method has been employed in studies on cellulose to distinguish between the different hydroxyl groups and their respective orientation and to explore possible hydrogen bonding patterns. 13,14,16,25 Deuteration techniques, 12,21,27 also in conjunction with polarized light, 22,26 have been utilized to assess the accessibility of hydroxyl groups and to distinguish amorphous and crystalline domains in cellulose. Second derivative 15,19 and deconvolution 17,18 processing of cellulose spectra have also resulted in a better resolution of O-H stretching bands.…”

Molecular orientation in the Nematic Ordered Cellulose film using polarized FTIR accompanied with a vapor-phase deuteration method

“…The former is considered due to the intramolecular hydrogen bonds; while the latter can be derived from the intermolecular hydrogen bonds (see Fig. 3; Hishikawa et al 1999Hishikawa et al , 2005. Here, it was assumed that the transition moment of OH groups would be almost parallel along the chemical bond.…”

“…Therefore, our objective in this study is to characterize the orientation separately for the main chains and the OH groups in the uniaxially drawn NOC film. To perform this, we employed our proposed method (Hishikawa et al 1999(Hishikawa et al , 2005 with a vapor-phase deuteration and the simultaneous measurement using the polarized Fourier transform infrared (FTIR) spectroscopy.…”

Deuterium and Cellulose: A Comprehensive Review

“…Intramolecular hydrogen bonds are O3-DˑˑˑO5 in each molecule, with a minor component involving O6 as acceptor [29] [33] allowed the authors to model and determine the possible hydrogen bonding modes of amorphous cellulose [41]. In a subsequent report, the same group employed two-dimensional correlation spectroscopy to characterize amorphous cellulose [42]. They assigned three different noncrystalline domains in the IR spectrum to OH vibrations and were able to distinguish between inter-and intramolecular hydrogen absorption bands.…”