Regensburg 2004 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 7: Spezielle Schichten III

DS 7.3: Vortrag

Montag, 8. März 2004, 12:00–12:15, HS 32

Effect of surface structure on hydrophobicity — •Phani Ayalasomayajula, Yvonne Gerbig, and Henry Haefke — CSEM Swiss Center for Electronics and Microtechnology, Inc., CH-2007 Neuchatel, Switzerland

Super hydrophobic surfaces can lead to applications in various fields. This work reports on a key feature of super hydrophobicity: the combined effect of chemistry and surface topography. Using the sol-gel technique, hydrophobic surfaces that are smooth and crack-free based on Poly[4,5 difluoro 2,2-bis (trifluoromethyl)-1,3 dioxole]-co-tetrafluoroethylene (TFE) were grown on glass. These were characterized using contact angle testing, UV-visible spectroscopy (UV-vis) and Fourier transform infrared (FTIR) spectroscopy to determine their wettabilty, optical absorbance as well as vibrational and stretching bands of the deposited films, respectively. Besides being hydrophobic, the deposited films are oleophobic, transparent with antireflective properties and hard. TFE films with thicknesses ranging from 5 nm to 50 nm were deposited on nanostructured chromium nitride coatings to investigate the combined effect of surface topography and chemistry upon film hydrophobicity. It was found that TFE coatings on a specific columnar growth structure formation of chromium nitride lead to an increase in the contact angle from 120 o to 147 o. Surface properties of the films have been examined using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) for morphology and elemental composition, respectively. The precise effect of surface morphology and roughness is discussed.