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Title

Tuning the hydrophobicity of mica surfaces by hyperthermal Ar ion irradiation

Author(s)

Keller, Adrian;  Fritzsche, Monika;  Ogaki, Ryosuke;  Bald, Ilko;  Facsko, Stefan;  Dong, Mingdong;  Kingshott, Peter;  Besenbacher, Flemming

Abstract

The hydrophobicity of surfaces has a strong influence on their interactions with biomolecules such as proteins. Therefore, for in vitro studies of bio-surface interactions model surfaces with tailored hydrophobicity are of utmost importance. Here, we present a method for tuning the hydrophobicity of atomically flat mica surfaces by hyperthermal Ar ion irradiation. Due to the sub-100 eV energies, only negligible roughening of the surface is observed at low ion fluences and also the chemical composition of the mica crystal remains almost undisturbed. However, the ion irradiation induces the preferential removal of the outermost layer of K+ ions from the surface, leading to the exposure of the underlying aluminosilicate sheets which feature a large number of centers for C adsorption. The irradiated surface thus exhibits an enhanced chemical reactivity toward hydrocarbons, resulting in the adsorption of a thin hydrocarbon film from the environment. Aging these surfaces under ambient conditions leads to a continuous increase of their contact angle until a fully hydrophobic surface with a contact angle ›80° is obtained after a period of about 3 months. This method thus enables the fabrication of ultrasmooth biological model surfaces with precisely tailored hydrophobicity.

Publication type

Journal article

Source

Journal of Chemical Physics, Vol. 134, no. 10 (2011), article no. 104705

Publication year

2011

FOR Code(s)

0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics;  0306 Physical Chemistry (Incl. Structural);  0904 Chemical Engineering

Keyword(s)

Cyclodextrin;  Elemental analysis;  DP-MS;  RAMAN;  TGA;  XRD;  XRS

Publisher

American Institute of Physics

ISSN

0021-9606

Publisher URL

http://dx.doi.org/10.1063/1.3561292

Copyright

Copyright © 2011 American Institute of Physics. Published version of this paper reproduced here with the kind permission of the publisher.

Full text

Peer reviewed