Europhys. Lett.
Volume 63, Number 3, August 2003
Page(s) 401 - 407
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 November 2003
DOI: 10.1209/epl/i2003-00538-7
Europhys. Lett., 63 (3) , pp. 401-407 (2003)

Influence of surface morphology on the wettability of cluster-assembled carbon films

L. Ostrovskaya1, A. Podestà2, P. Milani2 and V. Ralchenko3

1  Institute for Superhard Materials - Avtozavodskaya str. 2, 254074 Kiev, Ukraine
2  INFM, Dipartimento di Fisica, Università di Milano Via Celoria 16, 20133 Milano, Italy
3  General Physics Institute - Vavilova str. 38, 119991 Moscow, Russia

(Received 27 December 2002; accepted in final form 2 June 2003)

We have evaluated the surface energy and characterized the wettability of cluster-assembled carbon films deposited on polyethylene, $\chem{Si}$ and $\chem{Al}$ substrates by a sessile-drop method using water and glycerol. The effective surface energy of nanostructured carbon is of the order of 30 $\un{mJ/m^2}$ as calculated using the Fowkes approach. The advancing contact angle (66-83 $^{\circ}$) is found to increase with surface roughness, i.e. the surface becomes more hydrophobic as the roughness increases. This behavior is ascribed to gas trapping in pores of the film with a self-affine surface. It is argued that the wettability of nanostructured carbon and other cluster-assembled coatings can be tuned simply by controlling the surface topography, through a suitable control of the deposition parameters, such as the cluster size distribution.

68.08.Bc - Wetting.
68.35.Ct - Interface structure and roughness.
81.07.-b - Nanoscale materials and structures: fabrication and characterization.

© EDP Sciences 2003