Robust perfluorosilanized copper surfaces

Polished copper (Cu) surfaces modified with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (PFTS) have been shown to be very hydrophobic and stable. Mechanically polished, oxidized, and PFTS-reacted Cu surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy, which confirmed the presence of perfluorinated alkyl chains. For a PFTS-modified Cu surface (PFTS/Cu), the sessile drop static contact angle of pure water at ambient temperature and high relative humidity (RH) was measured to be more than 125 degrees and the Zisman critical surface energy to be typically less than 16 mN/m. Ellipsometry showed the thickness of the PFTS/Cu film to be typically less than 25 nm. Stability tests indicated that the PFTS/Cu film could survive in pure boiling water for one hour, boiling nitric acid (pH 1.5 or 1.8) for 30 min, sodium hydroxide solution (pH 12, 70 degrees C) for 30 min, and autoclave conditions (steam at 134 degrees C and 3 atm) for 15 min. The more commonly used self-assembled monolayer (SAM) modifications of Cu surfaces, e.g. thiol compounds, are significantly less stable than PFTS/Cu. The extremely hydrophobic and stable PFTS/Cu could be a very good candidate for corrosion inhibition and/or heat exchangers exploiting condensation. Copyright (c) 2005 John Wiley & Sons, Ltd.