Europhys. Lett.
Volume 72, Number 5, December 2005
Page(s) 844 - 850
Section Interdisciplinary physics and related areas of science and technology
Published online 03 November 2005
Europhys. Lett., 72 (5), pp. 844-850 (2005)
DOI: 10.1209/epl/i2005-10316-7

Adsorption energies of single charged polymers

C. Friedsam1, H. E. Gaub2 and R. R. Netz3

1  DEAS and Department of Physics, Harvard University Cambridge, MA 02138, USA
2  Center for Nanoscience, LMU München - Geschwister-Scholl Platz 1 80799 München, Germany
3  Physik Department, TU München - 85748 Garching, Germany

received 6 July 2005; accepted 6 October 2005
published online 3 November 2005

We peel off cationic and anionic polyelectrolytes from different substrates (cationic, hydrophobic and metallic) with the atomic force microscope (AFM). By varying the salt concentration, the measured plateau forces can be separated into electrostatic and non-electrostatic contributions to the adsorption energy. Surprisingly, i) the non-electrostatic contribution dominates even for highly charged substrates, and ii) hydrophobic substrates act like negatively charged surfaces. In the theoretical modeling the surface-induced charge regulation of the polymers has to be included.

87.16.Ac - Theory and modeling; computer simulation.
87.16.Dg - Membranes, bilayers, and vesicles.
87.68.+z - Biomaterials and biological interfaces.

© EDP Sciences 2005