Indentation and Self-Healing Mechanisms of a Self-Assembled Monolayer-A Combined Experimental and Modeling Study

Meltzer C, Paul J, Dietrich H, Jäger C, Clark T, Zahn D, Braunschweig B, Peukert W (2014)

Publication Language: English

Publication Type: Journal article

Publication year: 2014

Journal

Journal of the American Chemical Society American Chemical Society

Publisher: American Chemical Society

Book Volume: 136

Pages Range: 10718--10727

Volume: 136

Issue: 30

Journal Issue: 30

DOI: 10.1021/ja5048076

Abstract

A combination of in situ vibrational sum-frequency generation (SFG) spectroscopy and molecular-dynamics (MD) simulations has allowed us to study the effects of indentation of self-assembled octadecylphosphonic acid (ODPA) monolayers on α-Al2O3(0001). Stress-induced changes in the vibrational signatures of C-H stretching vibrations in SFG spectra and the results of MD simulations provide clear evidence for an increase in gauche-defect density in the monolayer as a response to indentation. A stress-dependent analysis indicates that the defect density reaches saturation at approximately 155 MPa. After stress is released, the MD simulations show an almost instantaneous healing of pressure-induced defects in good agreement with experimental results. The lateral extent of the contact areas was studied with colocalized SFG spectroscopy and compared to theoretical predictions for pressure gradients from Hertzian contact theory. SFG experiments reveal a gradual increase in gauche-defect density with pressure before saturation close to the contact center. Furthermore, our MD simulations show a spatial anisotropy of pressure-induced effects within ODPA domains: molecules tilted in the direction of the pressure gradient increase in tilt angle while those on the opposite side form gauche-defects.

Authors with CRIS profile

Christian Meltzer Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik Jonas Paul Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik Hanno Dietrich Computer-Chemie-Centrum Christof Jäger Computer-Chemie-Centrum Timothy Clark Computer-Chemie-Centrum Dirk Zahn Professur für Theoretische Chemie Björn Braunschweig Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik Wolfgang Peukert Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik

Additional Organisation(s)

Exzellenz-Cluster Engineering of Advanced Materials Graduiertenkolleg 1896/2 In situ Mikroskopie mit Elektronen, Röntgenstrahlen und Rastersonden Interdisziplinäres Zentrum, Center for Nanoanalysis and Electron Microscopy (CENEM)

How to cite

APA:

Meltzer, C., Paul, J., Dietrich, H., Jäger, C., Clark, T., Zahn, D.,... Peukert, W. (2014). Indentation and Self-Healing Mechanisms of a Self-Assembled Monolayer-A Combined Experimental and Modeling Study. Journal of the American Chemical Society, 136(30), 10718--10727. https://dx.doi.org/10.1021/ja5048076

MLA:

Meltzer, Christian, et al. "Indentation and Self-Healing Mechanisms of a Self-Assembled Monolayer-A Combined Experimental and Modeling Study." Journal of the American Chemical Society 136.30 (2014): 10718--10727.

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