Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-18T18:40:47.432Z Has data issue: false hasContentIssue false
  • English
  • Français

Nanomechanics of Self-Assembled Monolayers on Nanoscale Gold Films

Published online by Cambridge University Press:  01 February 2011

Milca I Aponte-Roman  and
Adrian B Mann
Milca I Aponte-Roman
Affiliation:
milcaa@eden.rutgers.edu, Rutgers, The State University of New Jersey, Materials Science & Engineering, 607 Taylor Road, Piscataway, NJ, 08854, United States
Adrian B Mann
Affiliation:
abmann@rci.rutgers.edu, Rutgers, The State University of New Jersey, Materials Science & Engineering, 607 Taylor Road, Piscataway, NJ, 08854, United States
Get access

Abstract

Self-assembled monolayers (SAMs) are thin organic films formed by a single layer of molecules adsorbed on a substrate. Since their discovery the preparation of these molecular assemblies has attracted the attention of interfacial researchers interested in controlled wetting of surfaces, adhesion, friction, chemical sensing, and high resolution lithography. However, little effort has gone into understanding how this nano-layer affects the mechanics of the underlying surface. In this study the nanomechanics of alkanethiolate SAMs on Au (111) films has been investigated using nanoindentation techniques. The research is aimed at establishing the effect of a SAM on the measured mechanical properties of the Au film. The SAMs considered for this study were made from 1-decanethiol, 96% (CH3(CH2)9-SH). Nanoindentation experiments were performed using a Triboindenter (Hysitron Inc., MN) using displacement control mode. Comparisons were made between the mechanical behavior of the Au films, the Au films plus SAMs and the glass substrate. A range of maximum indentation displacements were used. During the nanoindentation tests the load-displacement curves and the apparent mechanical properties were found to depend on the presence of the SAM film. Surprisingly, the effects of the SAM layer are seen even when the nanoindentation displacement is orders of magnitude greater that the SAM thickness. Many of the effects of the SAM can be explained by changes in the contact geometry and the ability of the SAM to sustain compressive loads when it is in a confined volume. The results and conclusions are potentially relevant to all thin adsorbed organic films, including protein layers on biomaterial surfaces and lubricants on engineering components.

Keywords

nano-indentationself-assemblythin film
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1086: Symposium U – Mechanics of Nanoscale Materials , 2008 , 1086-U08-27
Copyright
Copyright © Materials Research Society 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

[1] Bigelow, W. C., Pickett, D. L., and Zisman, W. A., “Oleophobic monolayers: I. Films adsorbed from solution in non-polar liquids,” Journal of Colloid Science, vol. 1, pp. 513–538, 1946.Google Scholar
[2] Nuzzo, R. G. and Allara, D. L., “Adsorption of bifunctional organic disulfides on gold surfaces,” J. Am. Chem. Soc., vol. 105, pp. 4481–4483, 1983.Google Scholar
[3] Troughton, E. B., Bain, C. D., Whitesides, G. M., Nuzzo, R. G., Allara, D. L., and Porter, M. D., “Monolayer films prepared by the spontaneous self-assembly of symmetrical and unsymmetrical dialkyl sulfides from solution onto gold substrates: structure, properties, and reactivity of constituent functional groups,” Langmuir, vol. 4, pp. 365–385, 1988.Google Scholar
[4] Nuzzo, R. G., Fusco, F. A., and Allara, D. L., “Spontaneously organized molecular assemblies. 3. Preparation and properties of solution adsorbed monolayers of organic disulfides on gold surfaces,” J. Am. Chem. Soc., vol. 109, pp. 2358–2368, 1987.Google Scholar
[5] Laibinis, P. E., Whitesides, G. M., Allara, D. L., Tao, Y. T., Parikh, A. N., and Nuzzo, R. G., “Comparison of the structures and wetting properties of self-assembled monolayers of nalkanethiols on the coinage metal surfaces, copper, silver, and gold,” J. Am. Chem. Soc., vol. 113, pp. 7152–7167, 1991.Google Scholar
[6] Srinivasan, U., Houston, M. R., Howe, R. T., and Maboudian, R., “Alkyltrichlorosilane-based self-assembled monolayer films for stiction reduction in silicon micromachines,” Microelectromechanical Systems, Journal of, vol. 7, pp. 252–260, 1998.Google Scholar
[7] Maboudian, R., Ashurst, W. R., and Carraro, C., “Self-assembled monolayers as anti-stiction coatings for MEMS: characteristics and recent developments,” Sensors and Actuators A: Physical, vol. 82, pp. 219–223, 2000.Google Scholar
[8] Carpick, R. W. and Salmeron, M., “Scratching the Surface: Fundamental Investigations of Tribology with Atomic Force Microscopy,” Chemical Reviews, vol. 97, pp. 1163–1194, 1997.Google Scholar
[9] Chaki, N. K. and Vijayamohanan, K., “Self-assembled monolayers as a tunable platform for biosensor applications,” Biosensors and Bioelectronics, vol. 17, pp. 1–12, 2002.Google Scholar
[10] Christman, K. L., Enriquez-Rios, V. D., and Maynard, H. D., “Nanopatterning proteins and peptides,” Soft Matter, vol. 2, pp. 928–939, 2006.Google Scholar
[11] Steven, T. P., Kalathil, C. E., Jeffrey, S. Z., Jeffrey, H. S., and Andrey, A. V., “Lubrication of microelectromechanical systems radio frequency switch contacts using self-assembled monolayers,” Journal of Applied Physics, vol. 102, p. 024903, 2007.Google Scholar
[12] Pham, T., Lai, D., Ji, D., Tuntiwechapikul, W., Friedman, J. M., and Lee, T. Randall, “Well-ordered self-assembled monolayer surfaces can be used to enhance the growth of protein crystals,” Colloids and Surfaces B: Biointerfaces, vol. 34, pp. 191–196, 2004.Google Scholar
[13] Meyer, U., Büchter, A., Wiesmann, H. P., Joos, U., and Jones, D. B., “Basic reactions of osteoblasts on structured material surfaces,” European Cells and Materials, vol. 9, pp. 39–49, 2005 Google Scholar
[14] Kiely, J. D., Hwang, R. Q., and Houston, J. E., “Effect of Surface Steps on the Plastic Threshold in Nanoindentation,” Physical Review Letters, vol. 81, p. 4424, 1998.Google Scholar
[15] Oliver, W. C. and Pharr, G. M., “An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments,” J. Mater. Res., vol. 7, pp. 1564–1583, 1992.Google Scholar
[16] Kluth, G. J., Carraro, C., and Maboudian, R., “Direct observation of sulfur dimers in alkanethiol self-assembled monolayers on Au(111),” Physical Review B, vol. 59, p. R10449, 1999.Google Scholar
[17] Mann, A. B., “Mechanics and geometry of nanoasperity contacts in organic fluids,” Appl. Phys. Lett., vol. 85, pp. 5203–5205, 2004.Google Scholar