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Instruments / Technical Area	Publication Details	Published	Actions
I07-Surface & interface diffraction	Structural order in cellulose thin films prepared from a trimethylsilyl precursor Andrew O. F. Jones , Roland Resel , Benedikt Schrode , Eduardo Machado-Charry , Christian Rothel , Birgit Kunert , Ingo Salzmann , Eero Kontturi , David Reishofer , Stefan Spirk Biomacromolecules DOI: 10.1021/acs.biomac.9b01377 Diamond Proposal Number(s): [13569] Show Abstract ▼ 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.	Nov 2019
I07-Surface & interface diffraction	Alkyl chain assisted thin film growth of 2,7-dioctyloxy-benzothienobenzothiophene Harald Spreitzer , Benjamin Kaufmann , Christian Ruzié , Christian Rothel , Thomas Arnold , Yves H. Geerts , Christian Teichert , Roland Resel , Andrew O. F. Jones Journal Of Materials Chemistry C 26 DOI: 10.1039/C9TC01979K Diamond Proposal Number(s): [13569] Open Access Show Abstract ▼ Abstract: An understanding of the thin film growth modes of substrate-induced polymorphs allows a deeper insight into the origin of this class of materials. Their onset of crystallisation, the subsequent crystal growth, the evolution of the thin film morphology and the transfer to the equilibrium bulk structure are still not fully understood. This work investigates the thin film formation of a conjugated molecule with terminal alkyl chains. Thin films of 2,7-dioctyloxy[1]benzothieno[3,2-b]benzothiophene were grown by physical vapor deposition on silicon oxide surfaces with varying the film thicknesses from the sub-monolayer regime up to 33 layer thick films. Additionally, the substrate temperature and deposition rate were varied. The films were investigated by atomic force microscopy, X-ray reflectivity and grazing incidence X-ray diffraction. The first growth stage is a closed monolayer with a thickness of 3 nm formed by upright-standing molecules. It is found that the substrate-induced crystal structure is already formed within the first monolayer and continues its growth up to the largest investigated film thickness. The characteristic morphology is terraced islands over the whole thickness range. On top of the first monolayer a morphology with several terrace levels appears, which is associated with a rapid increase of the surface roughness. At larger film thicknesses (≥13 nm) the number of terrace steps does not increase significantly, so that the surface roughness only increases slowly. This work shows that molecules with terminal alkyl chains can form a substrate-induced phase up to large film thicknesses without the appearance of the equilibrium bulk phase.	Jun 2019

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