Please use this identifier to cite or link to this item: doi:10.22028/D291-28890
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Title: Influence of bidisperse self-assembled monolayer structure on the slip boundary condition of thin polymer films
Author(s): McGraw, Joshua D
Klos, Mischa
Bridet, Antoine
Hähl, Hendrik
Paulus, Michael
Castillo, Juan Manuel
Horsch, Martin
Jacobs, Karin
Language: English
Title: The Journal of chemical physics
Volume: 146
Issue: 20
Publisher/Platform: American Institute of Physics (AIP)
Year of Publication: 2017
Publikation type: Journal Article
Abstract: Alkylsilane self-assembled monolayers (SAMs) are often used as model substrates for their ease of preparation and hydrophobic properties. We have observed that these atomically smooth monolayers also provide a slip boundary condition for dewetting films composed of unentangled polymers. This slip length, an indirect measure of the friction between a given liquid and different solids, is switchable and can be increased [R. Fetzer et al., Phys. Rev. Lett. 95, 127801 (2005); O. Bäumchen et al., J. Phys.: Condens. Matter 24, 325102 (2012)] if the alkyl chain length is changed from 18 to 12 backbone carbons, for example. Typically, this change in boundary condition is affected in a quantized way, using one or the other alkyl chain length, thus obtaining one or the other slip length. Here, we present results in which this SAM structure is changed in a continuous way. We prepare bidisperse mixed SAMs of alkyl silanes, with the composition as a control parameter. We find that all the mixed SAMs investigated show an enhanced slip boundary condition as compared to the single-component SAMs. The slip boundary condition is accessed using optical and atomic force microscopy, and we describe these observations in the context of X-ray reflectivity measurements. The slip length, varying over nearly two orders of magnitude, of identical polymer melts on chemically similar SAMs is found to correlate with the density of exposed alkyl chains. Our results demonstrate the importance of a well characterized solid/liquid pair, down to the angstrom level, when discussing the friction between a liquid and a solid.
DOI of the first publication: 10.1063/1.4978676
Link to this record: hdl:20.500.11880/27770
ISSN: 0021-9606
Date of registration: 13-Sep-2019
Faculty: NT - Naturwissenschaftlich- Technische Fakultät
Department: NT - Physik
Collections:UniBib – Die Universitätsbibliographie

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