Structural Order in Cellulose Thin Films Prepared from a Trimethylsilyl Precursor

Andrew O. F. Jones, Roland Resel*, Benedikt Schrode, Eduardo Machado-Charry, Christian Röthel, Birgit Kunert, Ingo Salzmann, Eero Kontturi, David Reishofer, Stefan Spirk

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

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 precharacterization 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 nanometers. The analysis of the diffraction patterns was based on the known structures of crystalline cellulose, as 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 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.
Original languageEnglish
Pages (from-to)653-659
Number of pages7
JournalBiomacromolecules
Volume21
Issue number2
Early online date12 Dec 2019
DOIs
Publication statusPublished - 10 Feb 2020

ASJC Scopus subject areas

  • Bioengineering
  • Materials Chemistry
  • Polymers and Plastics
  • Biomaterials

Fields of Expertise

  • Advanced Materials Science

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