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Structural order in cellulose thin films prepared from a trimethylsilyl precursor

DOI: 10.1021/acs.biomac.9b01377 DOI Help

Authors: Andrew O. F. Jones (Graz University of Technology) , Roland Resel (Graz University of Technology) , Benedikt Schrode (Graz University of Technology) , Eduardo Machado-charry (Graz University of Technology) , Christian Rothel (Graz University of Technology; Karl-Franzens University of Graz) , Birgit Kunert (Graz University of Technology) , Ingo Salzmann (Concordia University) , Eero Kontturi (Graz University of Technology) , David Reishofer (Graz University of Technology) , Stefan Spirk (Graz University of Technology)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Biomacromolecules

State: Published (Approved)
Published: November 2019
Diamond Proposal Number(s): 13569

Abstract: The biopolymer cellulose is investigated in terms of the crystallographic order within thin films. The films were prepared by spin coating of a trimethylsilyl cellulose precursor followed by an exposure to HCl vapors; two different source materials were used. Careful pre-characterization of the films was performed by infrared spectroscopy and atomic force microscopy. Subsequently, the films were investigated by grazing incidence X-ray diffraction using synchrotron radiation. The results showed broad diffraction peaks, indicating a rather short correlation length of the molecular packing in the range of a few nm. The analysis of the diffraction pattern was based on the known structures of crystalline cellulose, since the observed peak pattern was comparable to cellulose phase II and phase III. The dominant fraction of the film is formed by two different types of layers which are oriented parallel to the substrate surface. The stacking of the layers results in a one-dimensional crystallographic order with a defined interlayer distance of either 7.3 Å or 4.2 Å. As a consequence, two different preferred orientations of the polymer chains are observed. In both cases, polymer chain axes are aligned parallel to the substrate surface, and the orientation of the cellulose molecules are concluded to be either edge-on or flat-on. A minor fraction of the cellulose molecules form nanocrystals that are randomly distributed within the films. In this case, the molecular packing density was found to be smaller in comparison to the known crystalline phases of cellulose.

Subject Areas: Chemistry

Instruments: I07-Surface & interface diffraction

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